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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2013	Mar. 01, 2014	Jun. 30, 2013
Document and Entity Information
Entity Registrant Name	VERACYTE, INC.
Entity Central Index Key	0001384101
Document Type	10-K
Document Period End Date	Dec. 31, 2013
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		21,143,313
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	FY

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 71,220	$ 14,002
Accounts receivable, net of allowance of $107 and $222 as of December 31, 2013 and 2012	1,143	569
Supplies inventory	2,567	1,050
Prepaid expenses and other current assets	1,477	710
Restricted cash		50
Total current assets	76,407	16,381
Property and equipment, net	2,952	2,446
Restricted cash	118	118
Other assets	153	122
Total assets	79,630	19,067
Current liabilities:
Accounts payable	5,294	1,888
Accrued liabilities	7,594	4,020
Deferred Genzyme co-promotion fee	2,500	2,500
Preferred stock liability		583
Total current liabilities	15,388	8,991
Long-term debt, net of current portion	4,899
Deferred rent, net of current portion	286	61
Deferred Genzyme co-promotion fee, net of current portion	2,614	5,114
Total liabilities	23,187	14,166
Commitments and contingencies (Note 8)
Convertible preferred stock, $0.001 par value; 0 and 59,147,999 shares authorized, 0 and 53,084,507 shares issued and outstanding as of December 31, 2013 and December 31, 2012; aggregate liquidation value of $0 and $65,835 as of December 31, 2013 and 2012		63,372
Stockholders' deficit:
Common stock, $0.001 par value; 125,000,000 and 77,000,000 shares authorized, 21,143,313 and 667,684 shares issued and outstanding as of December 31, 2013 and 2012	21	1
Additional paid-in capital	142,071	1,597
Preferred stock, $0.001 par value; 5,000,000 and 0 shares authorized, 0 shares issued and outstanding as of December 31, 2013 and 2012
Accumulated deficit	(85,649)	(60,069)
Total stockholders' equity (deficit)	56,443	(58,471)
Total liabilities, convertible preferred stock, and stockholders' equity (deficit)	$ 79,630	$ 19,067

Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2013	Nov. 04, 2013	Dec. 31, 2012
Balance Sheets
Accounts receivable, allowance (in dollars)	$ 107		$ 222
Convertible preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0		59,147,999
Convertible preferred stock, shares issued	0		53,084,507
Convertible preferred stock, shares outstanding	0		53,084,507
Aggregate liquidation value	$ 0		$ 65,835
Common stock, par value (in dollars per share)	$ 0.001		$ 0.001
Common stock, shares authorized	125,000,000		77,000,000
Common stock, shares issued	21,143,313		667,684
Common stock, shares outstanding	21,143,313		667,684
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000	0
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statements of Operations and Comprehensive Loss
Revenue	$ 21,884	$ 11,628	$ 2,645
Operating expenses:
Cost of revenue	12,607	7,584	2,925
Research and development	7,810	6,608	6,680
Selling and marketing	12,540	8,447	2,934
General and administrative	12,100	7,918	5,372
Total operating expenses	45,057	30,557	17,911
Loss from operations	(23,173)	(18,929)	(15,266)
Interest income	5	2	2
Interest expense	(233)
Other income (expense), net	(2,179)	278	819
Net loss and comprehensive loss	$ (25,580)	$ (18,649)	$ (14,445)
Net loss per common share, basic and diluted (in dollars per share)	$ (6.15)	$ (28.68)	$ (24.90)
Shares used to compute net loss per common share, basic and diluted (in shares)	4,158,664	650,333	580,061

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands			1 Months Ended			2 Months Ended	12 Months Ended
	Dec. 02, 2013	Nov. 04, 2013	Jun. 30, 2013	Jul. 31, 2011	Feb. 28, 2011	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Increase (Decrease) in Convertible Preferred Stock and Stockholders' Equity (Deficit)
Balance							$ 63,372
Balance (in shares)							53,084,507
Balance							$ (58,471)	$ (40,766)	$ (26,811)
Issuance of common stock on exercise of stock options							$ 552	$ 76	24
Issuance of common stock on exercise of stock options (in shares)							377,966	72,743
Issuance of common stock in initial public offering, net of discounts and commissions of $4,642 and issuance costs of $2,507							$ 59,156
Issuance of common stock in initial public offering, net of discounts and commissions of $4,642 and issuance costs of $2,507 (in shares)	100,351	5,000,000
Conversion of preferred stock into common stock upon initial public offering							(79,022)
Conversion of preferred stock into common stock upon initial public offering (in shares)		(59,989,268)
Conversion of preferred stock into common stock upon initial public offering							79,022
Conversion of preferred stock into common stock upon initial public offering (in shares)		14,997,312
Reclassification of preferred stock warrant liability into additional paid-in capital upon initial public offering							261
Stock-based compensation expense (employee)							1,041	$ 590	378
Stock-based compensation expense (non employee)							206	85	88
Equity-based compensation							259	193
Common stock subject to repurchase							(3)
Net loss and comprehensive loss							(25,580)	(18,649)	(14,445)
Balance						$ 63,372		$ 63,372
Balance (in shares)						53,084,507	0	53,084,507
Balance						$ (58,471)	$ 56,443	$ (58,471)	(40,766)
Common Stock
Increase (Decrease) in Convertible Preferred Stock and Stockholders' Equity (Deficit)
Balance							$ 1	$ 1	$ 1
Balance (in shares)							667,684	594,941	556,844
Issuance of common stock on exercise of stock options (in shares)							377,966	72,743	38,097
Issuance of common stock in initial public offering, net of discounts and commissions of $4,642 and issuance costs of $2,507							$ 5
Issuance of common stock in initial public offering, net of discounts and commissions of $4,642 and issuance costs of $2,507 (in shares)							5,100,351
Conversion of preferred stock into common stock upon initial public offering							$ 15
Conversion of preferred stock into common stock upon initial public offering (in shares)							14,997,312
Balance						$ 1	$ 21	$ 1	$ 1
Balance (in shares)						667,684	21,143,313	667,684	594,941
Additional Paid-in Capital
Increase (Decrease) in Convertible Preferred Stock and Stockholders' Equity (Deficit)
Balance							$ 1,597	$ 653	$ 163
Issuance of common stock on exercise of stock options							552	76	24
Issuance of common stock in initial public offering, net of discounts and commissions of $4,642 and issuance costs of $2,507							59,151
Conversion of preferred stock into common stock upon initial public offering							79,007
Reclassification of preferred stock warrant liability into additional paid-in capital upon initial public offering							261
Stock-based compensation expense (employee)							1,041	590	378
Stock-based compensation expense (non employee)							206	85	88
Equity-based compensation							259	193
Common stock subject to repurchase							(3)
Balance						$ 1,597	142,071	1,597	653
Accumulated Deficit
Increase (Decrease) in Convertible Preferred Stock and Stockholders' Equity (Deficit)
Balance							(60,069)	(41,420)	(26,975)
Net loss and comprehensive loss							(25,580)	(18,649)	(14,445)
Balance						(60,069)	(85,649)	(60,069)	(41,420)
Convertible Preferred Stock
Increase (Decrease) in Convertible Preferred Stock and Stockholders' Equity (Deficit)
Balance							$ 63,372	$ 49,296	$ 30,674
Balance (in shares)							53,084,507	45,147,999	30,249,334
Extinguishment of the preferred stock liability							$ 2,653
Conversion of preferred stock into common stock upon initial public offering							$ (79,022)
Conversion of preferred stock into common stock upon initial public offering (in shares)							(59,989,268)
Balance						$ 63,372		$ 63,372	$ 49,296
Balance (in shares)						53,084,507		53,084,507	45,147,999
Series B
Increase (Decrease) in Convertible Preferred Stock and Stockholders' Equity (Deficit)
Balance (in shares)							22,748,000
Issuance of convertible preferred stock, net of issuance costs and preferred stock liability				$ 9,311	$ 9,311
Issuance of convertible preferred stock, net of issuance costs and preferred stock liability (in shares)				7,449,330	7,449,335
Balance (in shares)						22,748,000		22,748,000
Series C
Increase (Decrease) in Convertible Preferred Stock and Stockholders' Equity (Deficit)
Balance (in shares)							7,936,508
Issuance of convertible preferred stock, net of issuance costs and preferred stock liability			$ 12,997			$ 14,076
Issuance of convertible preferred stock, net of issuance costs and preferred stock liability (in shares)			6,904,761			7,936,508
Balance (in shares)						7,936,508		7,936,508

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			2 Months Ended	12 Months Ended
	Jun. 30, 2013	Jul. 31, 2011	Feb. 28, 2011	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Nov. 30, 2012
Issuance of convertible preferred stock, preferred stock liability						$ 861
Issuance of common stock in initial public offering, discounts and commissions					$ 4,642
Issuance of common stock in initial public offering, issuance cost					$ 2,507
Series B
Issuance of convertible preferred stock, issue price (in dollars per share)		$ 1.25	$ 1.25	$ 1.25		$ 1.25
Issuance of convertible preferred stock, issuance cost		$ 1	$ 1
Series C
Issuance of convertible preferred stock, issue price (in dollars per share)	$ 1.89			$ 1.89		$ 1.89	$ 1.89
Issuance of convertible preferred stock, issuance cost	$ 53			$ 63
Issuance of convertible preferred stock, preferred stock liability				$ 861

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities
Net loss	$ (25,580)	$ (18,649)	$ (14,445)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	999	706	611
Bad debt expense	109	225	235
Loss on write-off of property and equipment			215
Genzyme co-promotion fee amortization	(2,500)	(2,386)
Stock-based compensation	1,247	675	466
Equity-based compensation		259	193
Change in value of preferred stock liability	2,070	(278)	(719)
Change in value of preferred stock warrant liability	86
Amortization of debt discount and issuance costs	56
Interest on debt balloon payment	42
Changes in operating assets and liabilities:
Accounts receivable	(683)	(565)	(463)
Supplies inventory	(1,517)	(771)	(143)
Prepaid expenses and current other assets	(722)	(191)	(117)
Other assets	24	(119)	(1)
Accounts payable	3,348	1,348	116
Accrued liabilities and deferred rent	3,862	2,579	528
Deferred Genzyme co-promotion fee		10,000
Net cash used in operating activities	(19,159)	(7,167)	(13,524)
Investing activities
Purchases of property and equipment	(1,332)	(1,462)	(276)
Change in restricted cash	50		(55)
Net cash used in investing activities	(1,282)	(1,462)	(331)
Financing activities
Proceeds from the issuance of long-term debt, net of debt issuance costs	4,877
Proceeds from issuance of convertible preferred stock, net of issuance costs	12,945	14,989	18,622
Proceeds from issuance of common stock in initial public offering, gross	66,304
Commissions and issuance costs relating to the initial public offering	(7,019)
Proceeds from the exercise of common stock options	552	76	24
Net cash provided by financing activities	77,659	15,065	18,646
Net increase in cash and cash equivalents	57,218	6,436	4,791
Cash and cash equivalents at beginning of period	14,002	7,566	2,775
Cash and cash equivalents at end of period	71,220	14,002	7,566
Supplementary cash flow information of non cash investing and financing activities:
Purchases of property and equipment included in accounts payable and accrued liabilities	25	109	$ 106
Non-cash purchases of property and equipment	257
Preferred stock liability		861
Transfer of preferred stock liability to equity	2,653
Convertible preferred stock issuance costs included in accounts payable		52
Preferred stock warrants	175
Conversion of preferred stock warrant liability to common stock warrants	261
Conversion of convertible preferred stock to common stock	79,022
IPO costs included in accounts payable and accrued liabilities	129
Cash paid for interest on debt	132
Transfer of equity-based compensation from liabilities to equity	$ 259	$ 193

Organization and Description of Business	12 Months Ended
Organization and Description of Business	Dec. 31, 2013
Organization and Description of Business
Organization and Description of Business	1. Organization and Description of Business Veracyte, Inc. (the "Company") was incorporated in the state of Delaware on August 15, 2006 as Calderome, Inc. Calderome operated as an incubator until early 2008. On March 4, 2008, the Company changed its name to Veracyte, Inc. Veracyte is a diagnostics company pioneering the field of molecular cytology to improve patient outcomes and lower healthcare costs. The Company specifically targets diseases that often require invasive procedures for an accurate diagnosis—diseases where many healthy patients undergo costly interventions that ultimately prove unnecessary. The Company improves the accuracy of diagnosis at an earlier stage of patient care by deriving clinically actionable genomic information from cytology samples collected in an outpatient setting. The Company's first commercial solution, the Afirma Thyroid FNA Analysis, includes as its centerpiece the Gene Expression Classifier ("GEC"). The GEC helps physicians reduce the number of unnecessary surgeries by employing a proprietary 142-gene signature to preoperatively determine whether thyroid nodules previously classified by cytopathology as indeterminate can be reclassified as benign. The Company's operations are based in South San Francisco, California and Austin, Texas, and it operates in one segment in the United States. *Reverse Stock Split* On October 9, 2013, the Company filed a Certificate of Amendment to its Fourth Amended and Restated Certificate of Incorporation to effect a four-for-one reverse stock split of its outstanding common stock. The par value per share and the authorized number of shares of common stock and preferred stock were not adjusted as a result of the reverse stock split. All issued and outstanding shares of common stock, options to purchase common stock and related per share amounts contained in the financial statements have been retroactively adjusted to reflect the reverse stock split for all periods presented. A proportional adjustment to the conversion ratio for each series of convertible preferred stock was also effected in connection with the reverse stock split. The financial statements have not been retroactively adjusted to give effect to the conversion of the preferred stock into 0.25 of a share of common stock upon the closing of the IPO. *Initial Public Offering* On November 4, 2013, the Company completed an initial public offering ("IPO") of its common stock. In connection with its IPO, the Company issued and sold 5,000,000 shares of its common stock at a price to the public of $13.00 per share. Another 100,351 shares were issued on December 2, 2013. As a result of the IPO, the Company received approximately $59.2 million in net proceeds, after deducting underwriting discounts and commissions of $4.6 million and offering expenses of $2.5 million payable by the Company. In connection with the IPO, the Company's outstanding shares of convertible preferred stock were automatically converted into 14,997,312 shares of common stock.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2013

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The Company's financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("U.S. GAAP").

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Significant items subject to such estimates include: revenue recognition; contractual allowances; allowance for doubtful accounts; the useful lives of property and equipment; the recoverability of long-lived assets; the determination of fair value of the Company's common stock, stock options, preferred stock liability; income tax uncertainties, including a valuation allowance for deferred tax assets; and contingencies. The Company bases these estimates on historical and anticipated results, trends, and various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenue and expenses that are not readily apparent from other sources. Actual results could differ from those estimates and assumptions.

Concentrations of Credit Risk and Other Risks and Uncertainties

The Company's cash and cash equivalents are deposited with one major financial institution in the United States of America. Deposits in this institution may exceed the amount of insurance provided on such deposits. The Company has not experienced any losses on its deposits of cash and cash equivalents.

Several of the components of the Company's sample collection kit and test reagents are obtained from single-source suppliers. If these single-source suppliers fail to satisfy the Company's requirements on a timely basis, it could suffer delays in being able to deliver its diagnostic solution, a possible loss of revenue, or incur higher costs, any of which could adversely affect its operating results.

The Company is also subject to credit risk from its accounts receivable related to its sales of Afirma. The Company generally does not perform evaluations of customers' financial condition and generally does not require collateral. All of the Company's accounts receivables are derived from sales of Afirma in the United States.

Through December 31, 2013, all of the Company's revenues are derived from the sale of Afirma. The Company's solution to date has been delivered primarily to physicians in the United States. The Company's significant third-party payers and their related revenue as a percentage of total revenue are as follows:

	Year Ended December 31,

	2013			2012
Medicare		32	%		34	%
Aetna		9	%		13	%
UnitedHealthcare		18	%		12	%


		59	%		59	%

Accounts receivable from Medicare amounted to 78% and 87% of accounts receivable as of December 31, 2013 and 2012. No other third-party payer represented more than 10% of the Company's accounts receivable balances for these periods.

Cash Equivalents

Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase. Cash equivalents consist primarily of amounts invested in money market accounts.

Restricted Cash

Deposits of $118,000 and $168,000 as of December 31, 2013 and 2012, respectively, were restricted from withdrawal and held by a bank in the form of certificates of deposit and collateral for letters of credit. The balance as of December 31, 2013 and 2012 consists of a letter of credit totaling $118,000 held as security for the lease of the Company's office space in South San Francisco, California, and in 2012 the Company also had a certificate of deposit of $50,000 held as collateral for payment of the Company's credit cards.

Allowance for Doubtful Accounts

The Company estimates an allowance for doubtful accounts against its individual accounts receivable based on estimates of expected reimbursement consistent with historical payment experience in relation to the amounts billed. Bad debt expense is included in general and administrative expense on the Company's statements of operations and comprehensive loss. Accounts receivable are written off against the allowance when there is other substantive evidence that the account will not be paid. If the financial condition of our customers deteriorates, resulting in an impairment of their ability to make payment, additional allowances may be required.

	As of December 31,

	2013			2012
	(In thousands)
Beginning balance	$	222		$	235
Charged to expense		109			225
Write-offs, net of recoveries		(224	)		(238	)


Ending balance	$	107		$	222

Supplies Inventory

Supplies inventory consists of test reagents and other consumables used in the sample collection kits and in the GEC and are valued at the lower of cost or market value. Cost is determined using actual costs on a first-in, first-out basis.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, generally between three and five years. Leasehold improvements are amortized using the straight-line method over the shorter of the estimated useful life of the asset or the term of the lease. Maintenance and repairs are charged to expense as incurred, and improvements and betterments are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the balance sheet and any resulting gain or loss is reflected in the statements of operations and comprehensive loss in the period realized.

Internal-use Software

The Company capitalizes third-party costs incurred in the application development stage to design and implement the software used in the GEC. Costs incurred in the development of application of the software are capitalized and amortized over an estimated useful life of three years on a straight line basis.

During the years ended December 31, 2013 and 2012, the Company capitalized $212,000 and $173,000 of software development costs. Amortization expense totaled $108,000 and $47,000, for the years ended December 31, 2013 and 2012, respectively. The total cost, accumulated depreciation and net book value was $482,000, $195,000 and $287,000 at December 31, 2013, and was $271,000, $87,000 and $184,000 at December 31, 2012 and are included in property and equipment in the Company's balance sheets.

Long-lived Assets

The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. An impairment loss is recognized when the total of estimated future undiscounted cash flows, expected to result from the use of the asset and its eventual disposition, are less than its carrying amount. Impairment, if any, would be assessed using discounted cash flows or other appropriate measures of fair value. There were no impairments for the years ended December 31, 2013 and 2012.

Bonus Accruals

The Company accrues for liabilities under discretionary employee and executive bonus plans. These estimated compensation liabilities are based on progress against corporate objectives approved by the Board of Directors, compensation levels of eligible individuals, and target bonus percentage levels. The Board of Directors and the Compensation Committee of the Board of Directors review and evaluate the performance against these objectives and ultimately determine what discretionary payments are made. As of December 31, 2013 and 2012, the Company accrued $1.1 million and $0.7 million, respectively, for liabilities associated with these employee and executive bonus plans. As more fully discussed in Note 13 to the financial statements, a portion of the 2012 bonus accruals was settled with equity awards issued subsequent to the 2012 fiscal year end.

Fair Value of Financial Instruments

The carrying amounts of certain financial instruments including cash and cash equivalents, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities.

Revenue Recognition

The Company's revenue is generated from the provision of diagnostic services using the Afirma solution. The Company's service is completed upon the delivery of test results to the prescribing physician which triggers the billing for the service. The Company recognizes revenue related to billings for Medicare and commercial carriers on an accrual basis, net of contractual adjustments, when there is a predictable pattern of collectability. These contractual adjustments represent the difference between the list price (the billing rate) and the reimbursement rate set by Medicare or commercial payers. Upon ultimate collection, the amount received from Medicare and commercial payers with a predictable pattern of payment is compared to previous estimates and the contractual allowance is adjusted accordingly. Until a contract has been negotiated with a commercial carrier or governmental program, the Afirma solution may or may not be covered by these entities' existing reimbursement policies. In addition, patients do not enter into direct agreements with the Company that commit them to pay any portion of the cost of the tests in the event that their insurance declines to reimburse the Company. In the absence of an agreement with the patient or other clearly enforceable legal right to demand payment, the related revenue is only recognized upon the earlier of payment notification, if applicable, or cash receipt.

For all services performed, the Company considers whether or not the following revenue recognition criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the fee is fixed or determinable; and collectability is reasonably assured.

Persuasive evidence of an arrangement exists and delivery is deemed to have occurred upon delivery of a patient report to the prescribing physician. The assessment of the fixed or determinable nature of the fees charged for diagnostic testing performed and the collectability of those fees require significant judgment by management. Management believes that these two criteria have been met when there is contracted reimbursement coverage and/or a predictable pattern of collectability with individual third-party payers and accordingly, recognizes revenue upon delivery of the patient report. Some patients have out-of-pocket costs for amounts not covered by their insurance carrier, and the Company may bill the patient directly for these amounts in the form of co-payments and co-insurance in accordance with their insurance carrier and health plans. Some payers may not cover the Company's GEC as ordered by the prescribing physician under their reimbursement policies. The Company pursues reimbursement from such patients on a case-by-case basis. In the absence of contracted reimbursement coverage or a predictable pattern and history of collectability, the Company believes that the fee is fixed or determinable and collectability is reasonably assured only upon receipt of third-party payer notification of payment or when cash is received and accordingly, recognizes revenue at that time.

Cost of Revenue

Cost of revenue is expensed as incurred and includes material and service costs related to the initial cytopathology testing performed by a third-party pathology group, direct labor costs, equipment and infrastructure expenses associated with testing tissue samples, shipping charges to transport samples, and allocated overhead including rent, information technology, equipment depreciation and utilities.

Research and Development

Research and development costs are charged to operations as incurred. Research and development costs include, but are not limited to, payroll and personnel-related expenses, stock-based compensation expense, prototype materials, laboratory supplies, consulting costs, costs associated with setting up and conducting clinical studies at domestic and international sites, and allocated overhead including rent, information technology, equipment depreciation and utilities.

Income Taxes

The Company accounts for income taxes under the liability method. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized.

The Company assesses all material positions taken in any income tax return, including all significant uncertain positions, in all tax years that are still subject to assessment or challenge by relevant taxing authorities. The Company's assessment of an uncertain tax position begins with the initial determination of the position's sustainability and is measured at the largest amount of benefit that is greater than 50 percent likely of being realized upon ultimate settlement. As of each balance sheet date, unresolved uncertain tax positions must be reassessed, and the Company will determine whether (i) the factors underlying the sustainability assertion have changed and (ii) the amount of the recognized tax benefit is still appropriate. The recognition and measurement of tax benefits requires significant judgment. Judgments concerning the recognition and measurement of a tax benefit may change as new information becomes available.

Stock-based Compensation

Stock-based compensation expense for equity instruments issued to employees is measured based on the grant-date fair value of the awards. The fair value of each employee stock option is estimated on the date of grant using the Black-Scholes option-pricing valuation model. The Company recognizes compensation costs on a straight-line basis for all employee stock based compensation awards that are expected to vest over the requisite service period of the awards, which is generally the awards' vesting period. Forfeitures are required to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

Equity instruments issued to non-employees are valued using the Black-Scholes option-pricing valuation model and are subject to remeasurement as the underlying equity instruments vest.

Net Loss per Common Share

Basic net loss per common share is calculated by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. Diluted net loss per common share is computed by dividing net loss attributable to common stockholders by the weighted-average number of common share equivalents outstanding for the period determined using the treasury stock method. Potentially dilutive securities consisting of convertible preferred stock and options to purchase common stock are considered to be common stock equivalents and were excluded from the calculation of diluted net loss per common share because their effect would be anti-dilutive for all periods presented.

Recent Accounting Pronouncements

In July 2013, Financial Accounting Standards Board ("FASB"), issued Accounting Standards Update ("ASU"), No. 2013-11, Presentation of an Unrecognized Tax Benefit when a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists (a consensus of the FASB Emerging Issues Task Force). The amendments in this ASU provide guidance on the financial statements presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. An unrecognized tax benefit should be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward with certain exceptions, in which case such an unrecognized tax benefit should be presented in the financial statements as a liability. The amendments in this ASU do not require new recurring disclosures and are effective for fiscal years, and interim periods within those years, beginning after December 15, 2013. The Company is currently assessing the impact of this ASU on its financial statements.

In February 2013, the FASB issued ASU No. 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income. This ASU requires reporting and disclosure about changes in accumulated other comprehensive income balances and reclassifications out of accumulated other comprehensive income. The Company adopted this guidance as of January 1, 2013 on a prospective basis and its adoption did not have a material effect on its financial statements as the Company does not have comprehensive income (loss).

Net Loss Per Common Share

12 Months Ended

Dec. 31, 2013

Net Loss Per Common Share

Net Loss Per Common Share

3. Net Loss Per Common Share

The following table presents the calculation of basic and diluted net loss per common share for the years ended December 31, 2013, 2012 and 2011 (in thousands, except share and per share amounts):

	Year Ended December 31,

	2013			2012			2011
Net loss	$	(25,580	)	$	(18,649	)	$	(14,445	)




Shares used to compute net loss per common share, basic and diluted		4,158,664			650,333			580,061




Net loss per common share, basic and diluted	$	(6.15	)	$	(28.68	)	$	(24.90	)

The following outstanding shares of common stock equivalents have been excluded from diluted net loss per common share for the years ended December 31, 2013 and 2012 because their inclusion would be anti-dilutive:

	Year Ended December 31,

	2013		2012
Shares of common stock subject to outstanding options		2,359,287		2,227,669
Shares of common stock issuable upon conversion of preferred stock		—		13,271,122
Shares of common stock issuable upon exercise of warrants		24,801		—


Total shares of common stock equivalents		2,384,088		15,498,791

Balance Sheet Components

12 Months Ended

Dec. 31, 2013

Balance Sheet Components

Balance Sheet Components

4. Balance Sheet Components

Property and Equipment, Net

Property and equipment consisted of the following (in thousands):

	Year Ended December 31,

	2013			2012
Leasehold improvements	$	779		$	341
Laboratory equipment		2,946			2,061
Computer equipment		645			526
Software, including software developed for internal use		901			554
Furniture and fixtures		189			81
Construction-in-process		307			699


Total property and equipment, at cost		5,767			4,262
Accumulated depreciation and amortization		(2,815	)		(1,816	)


Total property and equipment, net	$	2,952		$	2,446

Depreciation and amortization expense was $999,000, $706,000 and $611,000 for the years ended December 31, 2013, 2012 and 2011, respectively, and was recorded in the statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31,

	2013		2012		2011
Cost of revenue	$	593	$	401	$	397
Research and development		179		184		162
Selling and marketing		54		46		21
General and administrative		173		75		31


Total depreciation and amortization expense	$	999	$	706	$	611

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	Year Ended December 31,

	2013		2012
Accrued compensation expenses	$	1,962	$	1,360
Accrued consulting fees		7		28
Accrued legal and professional fees		62		84
Accrued other		562		373
Accrued Genzyme co-promotion fees		4,915		2,175
Deferred rent—short-term		86		—


Total accrued liabilities	$	7,594	$	4,020

Fair Value Measurements

12 Months Ended

Dec. 31, 2013

Fair Value Measurements

Fair Value Measurements

5. Fair Value Measurements

The Company records its financial assets and liabilities at fair value. The carrying amounts of certain financial instruments of the Company, including cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued liabilities, approximate fair value due to their relatively short maturities. The carrying value of debt approximates its fair value because the interest rate approximates market rates that the Company could obtain for debt with similar terms. The accounting guidance for fair value provides a framework for measuring fair value, clarifies the definition of fair value, and expands disclosures regarding fair value measurements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows:

•

Level I: Inputs which include quoted prices in active markets for identical assets and liabilities.

•

Level II: Inputs other than Level I that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

•

Level III: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The following table sets forth the fair value of the Company's financial assets and liabilities measured on a recurring basis, as of December 31, 2013 and 2012 (in thousands):

	As of December 31, 2013

	Level I		Level II		Level III		Total
Financial Assets:
Money market funds	$	69,972	$	—	$	—	$	69,972


Total financial assets	$	69,972	$	—	$	—	$	69,972

	As of December 31, 2012

	Level I		Level II		Level III		Total
Financial Assets:
Money market funds	$	12,830	$	—	$	—	$	12,830


Total financial assets	$	12,830	$	—	$	—	$	12,830




Financial Liabilities:
Preferred stock liability	$	—	$	—	$	583	$	583


Total financial liabilities	$	—	$	—	$	583	$	583

The Company's Level 3 liabilities consist of a preferred stock liability (see Note 11). The following table sets forth a summary of the changes in the fair value of the Company's Level 3 financial liabilities, which are measured on a recurring basis (in thousands):

	December 31,

	2013			2012
Beginning balance	$	583		$	—
Fair value of preferred stock liability		—			861
Change in fair value of preferred stock liability recorded as other expense, net		2,070			(278	)
Settlement of preferred stock liability		(2,653	)		—
Fair value of preferred stock warrant liability		175			—
Change in fair value of preferred stock warrant liability recorded as other expense, net		86			—
Conversion of preferred stock warrant liability		(261	)		—


Ending balance	$	—		$	583

In November 2012, the Company recorded a preferred stock liability as investors received the right to purchase from the Company, on the same terms, additional shares of Series C convertible preferred stock, in a second tranche. As the investors held a majority of the board seats, the decision to complete the second tranche was deemed to be outside the control of the Company. The preferred stock liability was valued using the option-pricing method, which resulted in an initial fair value of $0.9 million for the Company's obligation to sell the convertible preferred stock. In June 2013, the Company settled the preferred stock liability upon completion of the sale of the second tranche of Series C convertible preferred stock. Immediately prior to settlement, the Company revalued the preferred stock liability to $2.7 million and recorded other expense of $2.1 million related to the change in value of the liability through that date. The preferred stock liability was valued using the option-pricing method with the following assumptions: 100% probability of success of the second tranche, fair value of Series C preferred stock of $2.39, a term of 0.003 years and expected volatility of 36.4%.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Genzyme Co-promotion Agreement

12 Months Ended

Dec. 31, 2013

Genzyme Co-promotion Agreement

Genzyme Co-promotion Agreement

6. Genzyme Co-promotion Agreement

In May 2011, the Company received $100,000 from Genzyme Corporation ("Genzyme") in connection with an extension of an exclusive right to negotiate a co-promotion agreement.

In January 2012, the Company and Genzyme executed a co-promotion agreement for the co-exclusive rights and license to promote and market the Company's Afirma thyroid cancer solution in the United States and in 40 named countries. In exchange, the Company received a $10.0 million co-promotion fee from Genzyme in February 2012. The Company may receive an additional $3.0 million in payments, $600,000 for each country outside of the United States in which the Company obtains marketing authorization and achieves a specified level of reimbursement, for up to five countries. Under the terms of the agreement, Genzyme will receive a percentage of cash receipts that the Company has received related to Afirma as co-promotion fees. The percentage was 50% in 2012, 40% beginning in January 2013 and will be reduced to 32% beginning on March 1, 2014 and thereafter. Genzyme will also spend up to $500,000 for qualifying clinical development activities in countries that require additional testing for approval. This obligation expires in July 2014. The agreement expires in January 2027 and either party may terminate the agreement at any time and with six months prior notice. The Company is amortizing the co-promotion fee over a four-year period, which is management's best estimate of the life of the agreement, in part because after that period either party may terminate the agreement without penalty. The Company incurred $8.6 million and $5.5 million in co-promotion expense in the years ended December 31, 2013 and 2012, respectively, which is included in the statements of operations and comprehensive loss. The Company amortized $2.5 million and $2.4 million of the $10.0 million up-front co-promotion fee in the years ended December 31, 2013 and 2012, which is reflected as a reduction to selling and marketing expenses in the statements of operations and comprehensive loss.

The unamortized balance of the co-promotion fee is reflected on the Company's balance sheet as follows (in thousands):

	Year Ended December 31,

	2013		2012
Current liabilities:
Deferred Genzyme co-promotion fee	$	2,500	$	2,500
Long-term liabilities:
Deferred Genzyme co-promotion fee, net of current portion		2,614		5,114


Total	$	5,114	$	7,614

Thyroid Cytopathology Partners	12 Months Ended
Thyroid Cytopathology Partners	Dec. 31, 2013
Thyroid Cytopathology Partners
Thyroid Cytopathology Partners	7. Thyroid Cytopathology Partners In 2010, the Company entered into an arrangement with Pathology Resource Consultants, P.A. ("PRC") to set up and manage a specialized pathology practice to provide testing services to the Company. There is no direct monetary compensation from the Company to PRC as a result of this arrangement. The Company's service agreement with the specialized pathology practice, Thyroid Cytopathology Partners ("TCP"), is effective through December 31, 2015, unless terminated earlier, and renews annually thereafter. Under the service agreement, Veracyte pays TCP based on a fixed price per test schedule, which is reviewed periodically for changes in market pricing. Subsequent to December 2012, an amendment to the service agreement allows TCP to use a portion of Veracyte's facility in Austin, Texas. Beginning in May 2013, TCP reimburses the Company for a proportionate share of the Company's rent and related operating expense costs for the leased facility. The Company does not have an ownership interest in or provide any form of financial or other support to TCP. The Company has concluded that TCP represents a variable interest entity and that the Company is not the primary beneficiary as it does not have the ability to direct the activities that most significantly impact TCP's economic performance. Therefore, the Company does not consolidate TCP. All amounts paid to TCP under the service agreement are expensed as incurred and included in cost of revenue in the statements of operations and comprehensive loss. All amounts to be received from TCP will be recorded in the same period as the corresponding lease costs. The Company incurred $3.2 million, $1.8 million and $434,000 in cytopathology testing and evaluation services expenses with TCP in the years ended December 31, 2013, 2012 and 2011, respectively. The Company also reimbursed TCP for licensure fees of $137,000 and $83,000 in the years ended December 31, 2012 and 2011, respectively. Beginning in 2013, the Company is no longer obligated to reimburse TCP for licensure fees. Expenses for testing and evaluation services and reimbursed professional licensure fees are included in cost of revenue in the statements of operations and comprehensive loss. The Company's outstanding obligations to TCP for cytopathology testing services were $588,000 and $458,000 as of December 31, 2013 and 2012, respectively, and are included in accounts payable in the Company's balance sheets. TCP's portion of rent and related operating expense costs for the shared space at the Austin, Texas facility was $49,000 for the year ended December 31, 2013. The reduction to rent expense is included in the Company's cost of revenue in the statements of operations and comprehensive loss. TCP reimbursed the Company $59,000 in 2013 and the resulting excess payment of $10,000 is included in accounts payable in the Company's balance sheet at December 31, 2013.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2013

Commitments and Contingencies

Commitments and Contingencies

8. Commitments and Contingencies

Operating Leases

The Company leases its headquarters and South San Francisco laboratory facilities under a non-cancelable lease agreement that expired March 31, 2013. The lease was amended in July 2012 to extend the term to March 31, 2016 and to provide tenant improvement allowances of up to $253,000. The Company provided security deposits in the form of irrevocable standby letters of credit secured with restricted cash deposits at the Company's primary bank. The Company deposited $118,000 in restricted cash accounts as collateral for the lease which is included in restricted cash in the Company's balance sheets as of December 31, 2013 and 2012.

In November 2012, the Company entered into a non-cancelable lease agreement commencing February 1, 2013 to lease laboratory space in Austin, Texas. The lease expires on July 31, 2018. The Company paid a cash security deposit of $75,000, which is included in other assets in the Company's balance sheet as of December 31, 2013 and 2012.

Future minimum lease payments under non-cancelable operating leases as of December 31, 2013 are as follows (in thousands):

Year Ending December 31,	Amounts

2014	$	938
2015		989
2016		413
2017		222
2018		130
Thereafter		—


Total minimum lease payments	$	2,692

The Company recognizes rent expense on a straight-line basis over the non-cancelable lease period. Facilities rent expense was $840,000, $711,000 and $570,000 for the years ended December 31, 2013, 2012 and 2011, respectively.

Volume Purchase Agreement

The Company had non-cancelable purchase obligations to contract manufacturers and suppliers for approximately $250,000 at December 31, 2013, of which $125,000 and $125,000 are estimated to be payable in the years ended December 31, 2014 and 2015, respectively.

Contingencies

From time to time, the Company may be involved in legal proceedings arising in the ordinary course of business. The Company believes there is no litigation pending that could have, individually or in the aggregate, a material adverse effect on the financial position, results of operations or cash flows.

Debt	12 Months Ended
Debt	Dec. 31, 2013
Debt
Debt	9. Debt In June 2013, the Company entered into a loan and security agreement with a financial institution to fund its working capital and other general corporate needs. The agreement provided for term loans of up to $10.0 million in aggregate. The Company drew down $5.0 million in funds under the agreement in June 2013. The carrying value of the debt approximates its fair value because the interest rate approximates market rates that the Company could obtain for debt with similar terms. The debt is a level 3 liability, and as more fully discussed in Note 5 to the financial statements, level 3 inputs include unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the underlying asset or liability. The Company is required to repay the outstanding principal in 30 equal installments beginning 18 months after the date of the borrowing. The loan bears interest at a rate of 6.06% per annum. The loan carries prepayment penalties of 2.25% and 1.5% for prepayment within one and two years, respectively, of the loan origination and 0.75% thereafter. The Company may request a second term loan of up to $5.0 million on or prior to March 31, 2014. As more fully discussed in Note 10 of the financial statements, upon execution of the loan and security agreement, the Company issued the financial institution a warrant to purchase shares of Series C convertible preferred stock at $7.56 per share. At the time of issuance, the aggregate fair value of the warrant for the 24,801 shares exercisable under the warrant was $175,000. The fair value of the warrant was deducted from total proceeds, resulting in a debt discount to be amortized to interest expense over 48 months, through the maturity date of the initial loan, using the effective interest rate method, and was recorded as a preferred stock warrant liability. As more fully discussed in Note 10 to the Financial Statements, the warrant was converted to a warrant to purchase the Company's common stock upon the completion of the IPO. The end of term payment of $223,000, representing 4.45% of the total outstanding principal balance, will be accreted over the life of the loan as interest expense. As a result of the debt discount and the end of term payment, the effective interest rate for the loan differs from the contractual rate. Total interest on the debt was $233,000 for the year ended December 31, 2013, including $75,000 in interest expense related to the amortization of the debt discount and accretion of the end of term payment, and $158,000 of nominal interest. The Company's obligations under the loan and security agreement are secured by a security interest in substantially all of its assets, excluding its intellectual property and certain other assets. The loan and security agreement contains customary conditions related to borrowing, events of default, and covenants, including covenants limiting the Company's ability to dispose of assets, undergo a change in control, merge with or acquire other entities, incur debt, incur liens, pay dividends or other distributions to holders of its capital stock, repurchase stock and make investments, in each case subject to certain exceptions. The agreement also allows the lender to call the debt in the event there is a material adverse change in the Company's business or financial condition. The loan and security agreement does not require that the Company comply with any financial covenants.

Convertible Preferred Stock Warrants	12 Months Ended
Convertible Preferred Stock Warrants	Dec. 31, 2013
Convertible Preferred Stock Warrants
Convertible Preferred Stock Warrants	10. Convertible Preferred Stock Warrants In June 2013, in conjunction with the execution of the loan and security agreement (Note 9), the Company issued to the lender a warrant to purchase up to 49,602 shares of Series C convertible preferred stock with an exercise price of $7.56 per share. Upon the draw down of the $5.0 million term loan, the warrant became exercisable for 24,801 shares. If the Company draws the second term loan, the remaining 24,801 shares will become exercisable under the warrant. The warrant expires at the earlier of (i) June 26, 2023 or (ii) the seventh anniversary of the Company's initial public offering. The warrant is exercisable in cash or through a cashless exercise provision. In connection with the IPO, as more fully described in Note 11, all of the Company's outstanding shares of convertible preferred stock were automatically converted into common stock and as a result, the warrant became exercisable for 24,801 shares of common stock (or 49,602 shares in the aggregate if the Company draws down the second term loan), at an exercise price of $7.56 per share. The fair value of the then currently exercisable portion of the warrant in the amount of $175,000 was recorded as a preferred stock warrant liability upon issuance and is subject to remeasurement at each reporting period up to the closing date of the IPO when the Series C preferred stock converted into common stock. The fair value of the warrant upon issuance was calculated using the Black-Scholes option-pricing valuation model with the following assumptions: Series C preferred stock value of $2.40 per share, contractual term of 7.3 years, risk-free interest rate of 2.1%, expected volatility of 73.7%, and expected dividend yield of 0%. Just prior to the closing of the IPO, the fair value of the warrant was approximately $261,000, and was calculated using the Black-Scholes option-pricing valuation model with the following assumptions: Series C preferred stock value of $13.14 per share, contractual term of 7.0 years, risk-free interest rate of 2.0%, expected volatility of 81.4%, and expected dividend yield of 0%. The change in the fair value of approximately $86,000 was reported as an expense for the year ended December 31, 2013 and is included in other income (expense), net in the statements of operations. The warrant was converted into a warrant to purchase common stock upon the completion of the IPO in 2013, and was reclassified to additional paid-in-capital in the Company's balance sheet. As a result, the warrant is no longer subject to fair value remeasurement. The warrant was exercised through a cashless exercise on March 17, 2014 resulting in the issuance of a net 13,739 shares of the Company's common stock.

Convertible Preferred Stock

12 Months Ended

Dec. 31, 2013

Convertible Preferred Stock

Convertible Preferred Stock

11. Convertible Preferred Stock

On November 4, 2013, the Company completed its IPO. In connection with the IPO, the Company's 59,989,268 outstanding shares of convertible preferred stock were automatically converted into 14,997,312 shares of common stock.

Convertible preferred stock as of December 31, 2012 consists of the following (in thousands, except for share data):

		Original Issue Price			Aggregate Liquidation Amount		Proceeds Net of Issuance Costs and Preferred Stock Liability

Series A	22,399,999	$	1.00	22,399,999		22,400		22,328
Series B	22,748,000		1.25	22,748,000		28,435		26,968
Series C	14,000,000		1.89	7,936,508		15,000		14,076


Balance at December 31, 2012	59,147,999			53,084,507	$	65,835	$	63,372

In November 2012, the Company entered into a Series C Preferred Stock Purchase Agreement (the "Series C Agreement"). Under the Series C Agreement, the Company authorized the issuance and sale of an aggregate of 13,227,513 shares of its Series C convertible preferred stock, which may be sold in three closings: 7,910,053 shares in the initial purchase (the "Initial Closing"), 5,291,005 shares in the second closing ("the Second Closing"), and 26,455 shares in an additional closing (the "First Additional Closing").

The Initial Closing of the Series C convertible preferred stock occurred in November 2012 and the First Additional Closing in December 2012. In the Initial Closing and the First Additional Closing, the Company issued an aggregate of 7,936,508 shares of its Series C convertible preferred stock at a price per share of $1.89 for gross proceeds of $15.0 million.

In June 2013, the Company amended its Amended and Restated Certificate of Incorporation to increase the number of authorized shares of Series C convertible preferred stock from 14,000,000 to 14,852,001 and amended the Series C Agreement to increase the number of shares that could be sold in additional closings from 26,455 to a total of 1,640,212. The Company completed the Second Closing and two additional closings under the Series C Agreement and received gross proceeds of $13.0 million for the issuance of 6,904,761 shares.

Preferred Stock Liability

In November 2012, the Company recorded a preferred stock liability as the investors received the right to purchase from the Company, on the same terms, additional shares of Series C convertible preferred stock, in a second tranche. As the investors hold a majority of the board seats, the decision to complete the second tranche was deemed to be outside the control of the Company. The preferred stock liability was valued using the option-pricing method with the following assumptions: 100% probability of success of the second tranche, fair value of Series C preferred stock of $1.78, a term of 0.67 years and expected volatility of 44%. This resulted in an initial fair value of $0.9 million for the Company's obligation to sell the convertible preferred stock. At December 31, 2012, the Company revalued the preferred stock liability to $0.6 million, and recorded the $0.3 million valuation decrease to other income (expense), net in the Company's statements of operations and comprehensive loss. In June 2013, the Company revalued the preferred stock liability to $2.7 million and recorded the $2.1 million valuation increase to other income (expense), net in the Company's statements of operations and comprehensive loss. In June 2013, the $2.7 million liability was settled upon the issuance of the second tranche of Series C convertible preferred stock and was reclassified to additional paid-in-capital in the Company's balance sheets.

Stockholders' Equity (Deficit)

12 Months Ended

Dec. 31, 2013

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)

12. Stockholders' Equity (Deficit)

Common Stock

The Company's Restated Certificate of Incorporation authorizes the Company to issue 125,000,000 shares of common stock with a par value of $0.001 per share. The holder of each share of common stock shall have one vote for each share of stock. The common stockholders are also entitled to receive dividends whenever funds and assets are legally available and when declared by the Board of Directors, subject to the prior rights of holders of all series of convertible preferred stock outstanding. No dividends have been declared as of December 31, 2013.

As of December 31, 2013 and 2012, the Company had reserved shares of common stock for issuance as follows:

	As of December 31,

	2013		2012
Conversion of Series A convertible preferred stock		—		5,599,999
Conversion of Series B convertible preferred stock		—		5,686,999
Conversion of Series C convertible preferred stock		—		1,984,124
Conversion of Series C convertible preferred stock reserved for issuance		—		1,322,751
Options issued and outstanding		2,359,287		2,227,669
Options available for grant under stock option plans		1,787,802		347,386
Common stock warrants issued and outstanding		24,801		—


Total		4,171,890		17,168,928

Preferred Stock

The Company's Restated Certificate of Incorporation, which became effective on November 4, 2013, authorizes the Company to issue 5,000,000 shares of preferred stock with a par value of $0.001 per share. No shares were issued and outstanding at December 31, 2013.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph d
-Article 4

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30, 31
-Article 5

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Article 4

Reference 18: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

Stock Incentive Plans

12 Months Ended

Dec. 31, 2013

Stock Incentive Plans

Stock Incentive Plans

13. Stock Incentive Plans

Stock Option Plans

On February 15, 2008, the Company adopted the 2008 Stock Plan (the "2008 Plan"). The 2008 Plan provides for the granting of options to purchase common stock and common stock to employees, directors and consultants of the Company. The Company may grant incentive stock options ("ISOs"), non-statutory stock options ("NSOs") or restricted stock under the 2008 Plan. ISOs may only be granted to Company employees (including directors who are also considered employees). NSOs and restricted stock may be granted to Company employees, directors and consultants. Options may be granted for terms of up to ten years from the date of grant, as determined by the Board of Directors, provided however, that with respect to an ISO granted to a person who owns stock representing more than 10% of the voting power of all classes of stock of the Company, the term shall be for no more than five years from the date of grant. The exercise price of options granted must be at a price no less than 100% of the estimated fair value of the shares on the date of grant, as determined by the Board of Directors, provided however, that with respect to an ISO granted to an employee who at the time of grant of such option owns stock representing more than 10% of the voting power of all classes of stock of the Company, the exercise price shall not be less than 110% of the estimated fair value of the shares on the date of grant. Options granted to newly hired employees generally vest over four years (generally 25% after one year and monthly thereafter). Options granted to employees as part of annual bonus compensation are generally fully vested at the grant date.

On October 2, 2013, the Company adopted the 2013 Stock Incentive Plan (the "2013 Plan"). The 2013 Plan was subsequently approved by the Company's stockholders and became effective on November 4, 2013, immediately before the closing of the IPO. Following the effectiveness of the 2013 Plan, no additional options will be granted under the 2008 Plan. An aggregate of 1,700,000 additional shares are reserved for issuance under the 2013 Plan. In addition, to the extent that any awards outstanding or subject to vesting restrictions under the 2008 Plan are subsequently forfeited or terminated for any reason before being exercised or settled, the shares of common stock reserved for issuance pursuant to such awards as of the closing of the IPO will become available for issuance under the 2013 Plan. The remaining shares available for grant under the 2008 Plan became available for issuance under the 2013 Plan upon the closing of the IPO. On the first day of each year from 2014 to 2023, the 2013 Plan authorizes an annual increase of the lesser of 4% of outstanding shares on the last day of the immediately preceding fiscal year or a lesser amount as determined by the Company's Board of Directors. As of December 31, 2013, 1,787,802 shares were available for future issuance under the 2013 Plan.

Pursuant to the 2013 Plan, stock options, restricted shares, stock units, including restricted stock units and stock appreciation rights may be granted to employees, consultants, and outside directors of the Company. Options granted may be either ISOs or NSOs.

Stock options are governed by stock option agreements between the Company and recipients of stock options. ISOs and NSOs may be granted under the 2013 Plan at an exercise price of not less than 100% of the fair market value of the common stock on the date of grant, determined by the Compensation Committee of the Board of Directors. Options become exercisable and expire as determined by the Compensation Committee, provided that the term of ISOs may not exceed ten years from the date of grant. Stock option agreements may provide for accelerated exercisability in the event of an optionee's death, disability, or retirement or other events.

Any outside director who was not previously an employee and who first joins the Company's Board of Directors on or after the effective date of the 2013 Plan will be automatically granted an initial NSO to purchase 35,000 shares of common stock upon first becoming a member of the Board of Directors. Twenty-five percent of the shares subject to the initial option will vest and become exercisable on the first anniversary of the date of grant. The balance (i.e. remaining 75%) will vest and become exercisable over three years in equal monthly installments. On the first business day after each regularly scheduled annual meeting of stockholders, each outside director who was not elected to the Board of Directors for the first time at such meeting and who will continue serving as a member of the Board of Directors thereafter will be automatically granted an option to purchase 10,000 shares of common stock, provided that the outside director has served on the Board of Directors for at least six months. Each annual option will vest and become exercisable on the first anniversary of the date of grant, or immediately prior to the next regular annual meeting of the Company's stockholders following the date of grant if the meeting occurs prior to the first anniversary date. The options granted to outside directors will have a per share exercise price equal to 100% of the fair market value of the underlying shares on the date of grant and will become fully vested in the event of a change of control. In addition, such options will terminate on the earlier of (i) the day before the 10th anniversary of the date of grant or (ii) the date 12 months after the termination of the outside director's termination of service for any reason.

Activity under the Company's stock option plans is set forth below (intrinsic value in thousands):

					Weighted Average Exercise Price			Aggregate Intrinsic Value

Balance—December 31, 2011	474,961		1,429,737		$	1.55	8.22	$	1,221
Additional options authorized	743,100		—
Granted	(931,944	)	931,944			2.78
Canceled	61,269		(61,269	)		1.97
Exercised	—		(72,743	)		1.05


Balance—December 31, 2012	347,386		2,227,669		$	2.06	8.17	$	4,311




Additional options authorized	1,950,000		—
Granted	(695,029	)	695,029			5.32
Canceled	185,445		(185,445	)		2.69
Exercised	—		(377,966	)		1.46


Balance—December 31, 2013	1,787,802		2,359,287		$	3.07	7.84	$	26,964




Options exercisable—December 31, 2013			1,273,335		$	2.10	7.12	$	15,788




Options vested and expected to vest—December 31, 2013			2,250,293		$	3.02	7.80	$	25,842

Outstanding and exercisable stock options as of December 31, 2013 are summarized as follows (intrinsic value in thousands):

	Options Outstanding						Options Vested and Exercisable

Exercise Prices	Number of Options Outstanding		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value		Number of Options Exercisable		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
$0.08		177,750		4.64	$	2,563		177,750		4.64	$	2,563
$0.80		165,569		6.14		2,268		158,458		6.13		2,171
$2.36		414,874		6.81		5,037		340,023		6.81		4,128
$2.40		208,593		7.68		2,524		147,299		7.69		1,782
$2.68		653,952		8.28		7,730		319,005		8.26		3,771
$4.00		473,299		9.08		4,970		130,800		9.06		1,373
$6.04		197,875		9.47		1,674		—		—		—
$7.92		9,000		9.69		59		—		—		—
$12.12		58,375		9.75		139		—				—


$0.08 - $12.12		2,359,287		7.84	$	26,964		1,273,335		7.12	$	15,788

The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock options and the fair value of the Company's common stock for stock options that were in-the-money.

The weighted average fair value of options to purchase common stock granted was $4.19 and $1.95 in the years ended December 31, 2013 and 2012, respectively.

The weighted average fair value of options to purchase common stock vested was $2.12 and $1.40 per share in the years ended December 31, 2013 and 2012. The total estimated grant date fair value of employee options to purchase common stock vested during the years ended December 31, 2013 and 2012 was $1.3 million and $0.6 million, respectively.

The weighted average fair value of options to purchase common stock exercised was $0.97 and $0.88 in the years ended December 31, 2013 and 2012, respectively. The intrinsic value of options to purchase common stock exercised was $4.9 million and $0.2 million in the years ended December 31, 2013 and 2012, respectively. The fair market value of the Company's common stock as of December 31, 2013 and 2012 was $14.50 and $4.00 per share, respectively.

Stock-based Compensation

The Company uses the grant date fair market value of its common stock to value both employee and non-employee options when granted. The Company revalues non-employee options each reporting period using the fair market value of the Company's common stock as of the last day of each reporting period.

Determining Fair Value of Stock Options

The fair value of the underlying common stock was determined by the Board of Directors until the IPO, when the Company's common stock started trading on The NASDAQ Global Select Market. Because there was no public market for the Company's common stock, the Board of Directors determined fair value of the common stock at the time of grant of the option by considering a number of objective and subjective factors including important developments in the Company's operations, valuations performed by an independent third party, sales of convertible preferred stock, actual operating results and financial performance, the conditions in our industry and the economy in general, the stock price performance of comparable public companies, and the lack of liquidity of the Company's common stock, among other factors.

The Black-Scholes option-pricing valuation model is used to determine the fair value of stock options. The input assumptions used to estimate fair value of these awards include the exercise price of the award, the expected option term, the expected volatility of the Company's stock over the option's expected term, the risk-free interest rate over the option's expected term, and the Company's expected dividend yield, if any.

The estimated expected term of options granted is determined by taking the average of the vesting term and the contractual term of each option. As the Company has limited stock price history from which to forecast stock price volatility, it estimates common stock price volatility by calculating the actual average volatility of the common stock of a selected peer group whose share price is publicly available. The Company uses a look-back period commensurate with the expected life of each option award. The risk-free interest rates used in the valuation model are based on U.S. Treasury issues with remaining terms similar to the expected term of the options. The Company does not anticipate paying any dividends in the foreseeable future and therefore used an expected dividend yield of zero.

Summary of Assumptions

The fair value of share-based payments for option granted to employees and directors was estimated on the date of grant using the Black-Scholes option-pricing valuation model based on the following weighted average assumptions:

	Year Ended December 31,

	2013	2012
Expected term (in years)	5.00 - 6.08	5.00 - 6.08
Expected volatility	80.42 - 81.41%	82.07 - 84.33%
Risk-free interest rate	0.88 - 2.11%	0.65 - 1.19%
Dividend yield	—	—

Stock-based compensation related to stock options granted to non-employees is recognized as the stock options are earned, generally through the provision of services. The Company believes the fair value of the stock-based awards is more reliably measureable than the fair value of services received. The fair value of the stock options granted is calculated at each reporting date using the Black-Scholes option-pricing model with the following assumptions: expected life is equal to the remaining contractual term of the award as of the measurement date ranging from 7.72 years to 9.75 years as of December 31, 2013 and 8.23 years to 9.93 years as of December 31, 2012; risk free rate is 2.59% to 2.99% for the year ended December 31, 2013 and 1.43% to 1.77% for the year ended December 31, 2012; expected dividend yield of 0%; and volatility ranging from 77.86% to 78.14% as of December 31, 2013 and 81.14% to 82.11% as of December 31, 2012.

The following table summarizes stock-based compensation expense related to stock options for the years ended December 31, 2013, 2012 and 2011, included in the statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31,

	2013		2012		2011
Cost of revenue	$	34	$	26	$	32
Research and development		250		131		130
Selling and marketing		169		111		77
General and administrative		794		407		227


Total stock-based compensation expense	$	1,247	$	675	$	466

If all of the remaining non-vested and outstanding stock option awards that have been granted vested, the Company would recognize approximately $2.7 million in compensation expense over a weighted average remaining period of 2.9 years. No compensation expense will be recognized for any stock options that do not vest.

Equity-based Compensation

For the year ended December 31, 2013, the Company will pay executive bonuses only in the form of cash.

For the years ended December 31, 2012 and 2011, the Company paid a portion of its executive bonuses through the grant of stock options. The equity transaction associated with these bonuses is classified as equity-based compensation expense. Accruals for the anticipated grants were $259,000 and $193,000 in the years ended December 31, 2012 and 2011, respectively, and are included in accrued liabilities in the balance sheets. The expenses were determined as follows:

•

In March 2012, the Company's Board of Directors authorized the grant of 109,653 fully vested stock options at a fair value of $1.76 resulting in $193,000 in expense in the year ended December 31, 2011. The fair value of the options was determined using the Black-Scholes option-pricing valuation model with the following assumptions: the option exercise strike price was $2.68 equal to the fair market value of the Company's common stock at grant date, risk free rate of 0.88%, expected term of 5.0 years, volatility rate of 83.52% and expected dividend yield of 0%. Upon issuance of the fully vested options, the liability was reclassified into additional paid-in capital.

•

In February 2013, the Company's Board of Directors authorized the grant of 100,498 fully vested stock options at a fair value of $2.59 resulting in $259,000 in expense in the year ended December 31, 2012. The fair value of the options was determined using the Black-Scholes option-pricing valuation model with the following assumptions: the option exercise strike price was $4.00 equal to the fair market value of the Company's common stock at grant date, risk-free rate of 0.88%, expected term of 5.0 years, volatility rate of 81.41% and expected dividend yield of 0%. Upon issuance of the fully vested options, the liability was reclassified into additional paid-in capital.

The following table summarizes equity-based compensation expense for the years ended December 31, 2013, 2012 and 2011, which were included in the statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31,

	2013		2012		2011
Cost of revenue	$	—	$	2	$	2
Research and development		—		100		80
Selling and marketing		—		39		41
General and administrative		—		118		70


Total equity-based compensation expense	$	—	$	259	$	193

Income Taxes

12 Months Ended

Dec. 31, 2013

Income Taxes

Income Taxes

14. Income Taxes

The Company generated a pretax loss of $25.6 million, $18.6 million and $14.4 million in the United States for the years ended December 31, 2013, 2012 and 2011, respectively. Since inception, the Company has not generated any pretax income or loss outside of the United States. The Company did not record a provision or benefit for income taxes during the years ended December 31, 2013, 2012 and 2011. The Company follows FASB ASC No. 740, Income Taxes for the Computation and Presentation of its Tax Provision. The following table presents a reconciliation of the tax expense computed at the statutory federal rate and the Company's tax expense for the period presented (in thousands):

	Year Ended December, 31,

	2013			2012			2011
U.S. federal taxes at statutory rate	$	(8,697	)	$	(6,341	)	$	(4,911	)
State taxes (net of federal benefit)		11			(1,074	)		(843	)
Permanent differences		1,145			261			(108	)
Tax credits		(502	)		(113	)		(181	)
Change in valuation allowance		8,043			7,267			6,043


Total	$	—		$	—		$	—

The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets are as follows (in thousands):

	As of December 31,

	2013			2012			2011
Current deferred tax assets:
Net operating loss carryforwards	$	—		$	—		$	—
Research and development credit		—			—			—
Stock-based compensation		—			—			—
Genzyme co-promotion agreement		1,005			1,001			—
Accruals and deferred rent		599			148			—


Gross deferred tax assets		1,604			1,149			—
Valuation allowance		(1,603	)		(1,145	)		—


Net deferred tax assets		1			4			—


Deferred tax liabilities:
Property and equipment		—			—			—


Gross deferred tax liabilities		—			—			—


Net current deferred tax liabilities		1			4			—


Non-current deferred tax assets:
Net operating loss carryforwards		28,569			20,536			16,547
Research and development credit		1,455			954			723
Stock-based compensation		313			154			50
Genzyme co-promotion agreement		787			2,048			—
Accruals, depreciation and deferred rent		106			9			197


Gross deferred tax assets		31,230			23,701			17,517
Valuation allowance		(31,216	)		(23,622	)		(17,469	)


Net deferred tax assets		14			79			48


Deferred tax liabilities:
Property and equipment		(15	)		(83	)		(48	)


Gross deferred tax liabilities		(15	)		(83	)		(48	)


Net non-current deferred tax liabilities		(1	)		(4	)		—


Total deferred tax assets	$	—		$	—		$	—

The Company has established a full valuation allowance against its deferred tax assets due to the uncertainty surrounding realization of such assets. The valuation allowance increased $8.1 million and $7.3 million during the years ended December 31, 2013 and 2012, respectively.

The Company had $0.3 million of cumulative excess tax benefits from stock option deductions generated subsequent to the adoption of the authoritative guidance regarding stock-based compensation, which are not included in the net operating loss carryforward amounts above since they have not met the required realization criteria. The Company considers stock option deduction benefits in excess of book compensation charges realized when it obtains an incremental benefit determined by the "with and without" calculation method, under which excess tax benefits related to stock-based compensation are not deemed to be realized until after the utilization of all other tax benefits available to the Company. When realized, these benefits will increase additional paid-in capital.

As of December 31, 2013, the Company had net operating loss carryforwards of approximately $75.1 million and $54.0 million available to reduce future taxable income, if any, for Federal and state income tax purposes, respectively. The U.S. federal net operating loss carryforwards will begin to expire in 2026 while for state purposes, the net operating losses will begin to expire in 2018.

As of December 31, 2013, the Company had credit carryforwards of approximately $1.4 million and $1.0 million available to reduce future taxable income, if any, for Federal and California state income tax purposes, respectively. The Federal credit carryforwards begin to expire in 2028. California credits have no expiration date.

The Internal Revenue Code of 1986, as amended, imposes restrictions on the utilization of net operating losses and tax credits in the event of an "ownership change" of a corporation. Accordingly, a company's ability to use net operating losses and tax credits may be limited as prescribed under Internal Revenue Code Section 382 and 383 ("IRC Section 382"). Events which may cause limitations in the amount of the net operating losses or tax credits that the Company may use in any one year include, but are not limited to, a cumulative ownership change of more than 50% over a three-year period. Utilization of the federal and state net operating losses may be subject to substantial annual limitation due to the ownership change limitations provided by the IRC Section 382 rules and similar state provisions. In the event the Company has any changes in ownership, net operating losses and research and development credit carryovers could be limited and may expire unutilized.

As of December 31, 2013, the Company had unrecognized tax benefits of $0.7 million, all of which would not currently affect the Company's effective tax rate if recognized due to the Company's deferred tax assets being fully offset by a valuation allowance. The Company does not anticipate that the amount of unrecognized tax benefits relating to tax positions existing at December 31, 2013 will significantly increase or decrease within the next twelve months.

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):

	Year Ended December 31,

	2013		2012		2011
Unrecognized tax benefits, beginning of period	$	481	$	341	$	263
Gross increases—tax position in prior period		68		67		—
Gross decrease—tax position in prior period		—		—		—
Gross increases—current period tax positions		178		73		78
Lapse of statute of limitations		—		—		—


Unrecognized tax benefits, end of period	$	728	$	481	$	341

It is the Company's policy to include penalties and interest expense related to income taxes as a component of other expense and interest expense, respectively, as necessary. There was no interest expense or penalties related to unrecognized tax benefits recorded through December 31, 2013.

The Company's major tax jurisdictions are the United States and California. All of the Company's tax years will remain open for examination by the Federal and state tax authorities for three and four years, respectively, from the date of utilization of the net operating loss or research and development credit. The Company does not have any tax audits pending.

401(k) Plan	12 Months Ended
401(k) Plan	Dec. 31, 2013
401(k) Plan
401(k) Plan	15. 401(k) Plan The Company sponsors a 401(k) defined contribution plan covering all employees. There were no employer contributions to the plan in the years ended December 31, 2013 and 2012.

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2013

Selected Quarterly Financial Data (Unaudited)

Selected Quarterly Financial Data (Unaudited)

16. Selected Quarterly Financial Data (Unaudited)

The following table presents selected unaudited consolidated financial data for each of the eight quarters in the two-year period ended December 31, 2013. The Company believes this information reflects all recurring adjustments necessary to fairly present this information when read in conjunction with the Company's financial statements and the related notes. Net loss per share-basic and diluted, for the four quarters of each fiscal year may not sum to the total for the fiscal year because of the different number of shares outstanding during each period. The results of operations for any quarter are not necessarily indicative of the results to be expected for any future period.

Quarter Ended:	March 31			June 30			September 30			December 31

	(In thousands, except share and per share data)
2013:
Total revenues	$	4,384		$	5,068		$	5,594		$	6,838
Net loss	$	(6,895	)	$	(6,490	)	$	(6,303	)	$	(5,892	)
Net loss per common share, basic and diluted	$	(9.04	)	$	(7.53	)	$	(6.59	)	$	(0.42	)
Shares used in calculation of net loss per share, basic and diluted		763,021			861,839			955,890			13,944,239
2012:
Total revenues	$	1,468		$	2,479		$	3,224		$	4,457
Net loss	$	(4,248	)	$	(4,626	)	$	(4,938	)	$	(4,837	)
Net loss per common share, basic and diluted	$	(6.81	)	$	(7.08	)	$	(7.49	)	$	(7.27	)
Shares used in calculation of net loss per share, basic and diluted		623,515			653,121			659,129			665,306

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2013

Summary of Significant Accounting Policies

Basis of Presentation

Basis of Presentation

The Company's financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("U.S. GAAP").

Use of Estimates

Use of Estimates

Concentrations of Credit Risk and Other Risks and Uncertainties

Concentrations of Credit Risk and Other Risks and Uncertainties

	Year Ended December 31,

	2013			2012
Medicare		32	%		34	%
Aetna		9	%		13	%
UnitedHealthcare		18	%		12	%


		59	%		59	%

Cash Equivalents

Cash Equivalents

Restricted Cash

Restricted Cash

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts

	As of December 31,

	2013			2012
	(In thousands)
Beginning balance	$	222		$	235
Charged to expense		109			225
Write-offs, net of recoveries		(224	)		(238	)


Ending balance	$	107		$	222

Supplies Inventory

Supplies Inventory

Property and Equipment

Property and Equipment

Internal-use Software

Internal-use Software

Long-lived Assets

Long-lived Assets

Bonus Accruals

Bonus Accruals

Fair Value of Financial Instruments

Fair Value of Financial Instruments

Revenue Recognition

Revenue Recognition

Cost of Revenue

Cost of Revenue

Research and Development

Research and Development

Income Taxes

Income Taxes

Stock-based Compensation

Stock-based Compensation

Equity instruments issued to non-employees are valued using the Black-Scholes option-pricing valuation model and are subject to remeasurement as the underlying equity instruments vest.

Net Loss per Common Share

Net Loss per Common Share

Recent Accounting Pronouncements

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2013

Summary of Significant Accounting Policies

Schedule of the Company's significant third-party payers and their related revenue as a percentage of total revenue

	Year Ended December 31,

	2013			2012
Medicare		32	%		34	%
Aetna		9	%		13	%
UnitedHealthcare		18	%		12	%


		59	%		59	%

Schedule of activity of allowance for doubtful accounts

	As of December 31,

	2013			2012
	(In thousands)
Beginning balance	$	222		$	235
Charged to expense		109			225
Write-offs, net of recoveries		(224	)		(238	)


Ending balance	$	107		$	222

Net Loss Per Common Share (Tables)

12 Months Ended

Dec. 31, 2013

Net Loss Per Common Share

Schedule of the calculation of basic and diluted net loss per common share

The following table presents the calculation of basic and diluted net loss per common share for the years ended December 31, 2013, 2012 and 2011 (in thousands, except share and per share amounts):

	Year Ended December 31,

	2013			2012			2011
Net loss	$	(25,580	)	$	(18,649	)	$	(14,445	)




Shares used to compute net loss per common share, basic and diluted		4,158,664			650,333			580,061




Net loss per common share, basic and diluted	$	(6.15	)	$	(28.68	)	$	(24.90	)

Schedule of outstanding shares of common stock equivalents that have been excluded from diluted net loss per common share

	Year Ended December 31,

	2013		2012
Shares of common stock subject to outstanding options		2,359,287		2,227,669
Shares of common stock issuable upon conversion of preferred stock		—		13,271,122
Shares of common stock issuable upon exercise of warrants		24,801		—


Total shares of common stock equivalents		2,384,088		15,498,791

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2013

Balance Sheet Components

Schedule of Property and equipment

Property and equipment consisted of the following (in thousands):

	Year Ended December 31,

	2013			2012
Leasehold improvements	$	779		$	341
Laboratory equipment		2,946			2,061
Computer equipment		645			526
Software, including software developed for internal use		901			554
Furniture and fixtures		189			81
Construction-in-process		307			699


Total property and equipment, at cost		5,767			4,262
Accumulated depreciation and amortization		(2,815	)		(1,816	)


Total property and equipment, net	$	2,952		$	2,446

Schedule of depreciation and amortization expense recorded in the statements of operations and comprehensive loss

	Year Ended December 31,

	2013		2012		2011
Cost of revenue	$	593	$	401	$	397
Research and development		179		184		162
Selling and marketing		54		46		21
General and administrative		173		75		31


Total depreciation and amortization expense	$	999	$	706	$	611

Schedule of accrued liabilities

Accrued liabilities consisted of the following (in thousands):

	Year Ended December 31,

	2013		2012
Accrued compensation expenses	$	1,962	$	1,360
Accrued consulting fees		7		28
Accrued legal and professional fees		62		84
Accrued other		562		373
Accrued Genzyme co-promotion fees		4,915		2,175
Deferred rent—short-term		86		—


Total accrued liabilities	$	7,594	$	4,020

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2013

Fair Value Measurements

Schedule of the fair value of the Company's financial assets and liabilities measured on a recurring basis

The following table sets forth the fair value of the Company's financial assets and liabilities measured on a recurring basis, as of December 31, 2013 and 2012 (in thousands):

	As of December 31, 2013

	Level I		Level II		Level III		Total
Financial Assets:
Money market funds	$	69,972	$	—	$	—	$	69,972


Total financial assets	$	69,972	$	—	$	—	$	69,972

	As of December 31, 2012

	Level I		Level II		Level III		Total
Financial Assets:
Money market funds	$	12,830	$	—	$	—	$	12,830


Total financial assets	$	12,830	$	—	$	—	$	12,830




Financial Liabilities:
Preferred stock liability	$	—	$	—	$	583	$	583


Total financial liabilities	$	—	$	—	$	583	$	583

Summary of the changes in the fair value of the Company's Level 3 financial liabilities, which are measured on a recurring basis

The following table sets forth a summary of the changes in the fair value of the Company's Level 3 financial liabilities, which are measured on a recurring basis (in thousands):

	December 31,

	2013			2012
Beginning balance	$	583		$	—
Fair value of preferred stock liability		—			861
Change in fair value of preferred stock liability recorded as other expense, net		2,070			(278	)
Settlement of preferred stock liability		(2,653	)		—
Fair value of preferred stock warrant liability		175			—
Change in fair value of preferred stock warrant liability recorded as other expense, net		86			—
Conversion of preferred stock warrant liability		(261	)		—


Ending balance	$	—		$	583

Genzyme Co-promotion Agreement (Tables)

12 Months Ended

Dec. 31, 2013

Genzyme Co-promotion Agreement

Schedule of unamortized balance of the co-promotion fee reflected in the Company's balance sheet

The unamortized balance of the co-promotion fee is reflected on the Company's balance sheet as follows (in thousands):

	Year Ended December 31,

	2013		2012
Current liabilities:
Deferred Genzyme co-promotion fee	$	2,500	$	2,500
Long-term liabilities:
Deferred Genzyme co-promotion fee, net of current portion		2,614		5,114


Total	$	5,114	$	7,614

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2013

Commitments and Contingencies

Schedule of future minimum lease payments under non-cancelable operating leases

Future minimum lease payments under non-cancelable operating leases as of December 31, 2013 are as follows (in thousands):

Year Ending December 31,	Amounts

2014	$	938
2015		989
2016		413
2017		222
2018		130
Thereafter		—


Total minimum lease payments	$	2,692

Convertible Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2013

Convertible Preferred Stock

Schedule of convertible preferred stock

Convertible preferred stock as of December 31, 2012 consists of the following (in thousands, except for share data):

		Original Issue Price			Aggregate Liquidation Amount		Proceeds Net of Issuance Costs and Preferred Stock Liability

Series A	22,399,999	$	1.00	22,399,999		22,400		22,328
Series B	22,748,000		1.25	22,748,000		28,435		26,968
Series C	14,000,000		1.89	7,936,508		15,000		14,076


Balance at December 31, 2012	59,147,999			53,084,507	$	65,835	$	63,372

Stockholders' Equity (Deficit) (Tables)

12 Months Ended

Dec. 31, 2013

Stockholders' Equity (Deficit)

Schedule of reserved shares of common stock for issuance

	As of December 31,

	2013		2012
Conversion of Series A convertible preferred stock		—		5,599,999
Conversion of Series B convertible preferred stock		—		5,686,999
Conversion of Series C convertible preferred stock		—		1,984,124
Conversion of Series C convertible preferred stock reserved for issuance		—		1,322,751
Options issued and outstanding		2,359,287		2,227,669
Options available for grant under stock option plans		1,787,802		347,386
Common stock warrants issued and outstanding		24,801		—


Total		4,171,890		17,168,928

Stock Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2013

Stock incentive plans

Summary of activity under the Company's stock option plans

Activity under the Company's stock option plans is set forth below (intrinsic value in thousands):

					Weighted Average Exercise Price			Aggregate Intrinsic Value

Balance—December 31, 2011	474,961		1,429,737		$	1.55	8.22	$	1,221
Additional options authorized	743,100		—
Granted	(931,944	)	931,944			2.78
Canceled	61,269		(61,269	)		1.97
Exercised	—		(72,743	)		1.05


Balance—December 31, 2012	347,386		2,227,669		$	2.06	8.17	$	4,311




Additional options authorized	1,950,000		—
Granted	(695,029	)	695,029			5.32
Canceled	185,445		(185,445	)		2.69
Exercised	—		(377,966	)		1.46


Balance—December 31, 2013	1,787,802		2,359,287		$	3.07	7.84	$	26,964




Options exercisable—December 31, 2013			1,273,335		$	2.10	7.12	$	15,788




Options vested and expected to vest—December 31, 2013			2,250,293		$	3.02	7.80	$	25,842

Summary of outstanding and exercisable stock options

Outstanding and exercisable stock options as of December 31, 2013 are summarized as follows (intrinsic value in thousands):

	Options Outstanding						Options Vested and Exercisable

Exercise Prices	Number of Options Outstanding		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value		Number of Options Exercisable		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
$0.08		177,750		4.64	$	2,563		177,750		4.64	$	2,563
$0.80		165,569		6.14		2,268		158,458		6.13		2,171
$2.36		414,874		6.81		5,037		340,023		6.81		4,128
$2.40		208,593		7.68		2,524		147,299		7.69		1,782
$2.68		653,952		8.28		7,730		319,005		8.26		3,771
$4.00		473,299		9.08		4,970		130,800		9.06		1,373
$6.04		197,875		9.47		1,674		—		—		—
$7.92		9,000		9.69		59		—		—		—
$12.12		58,375		9.75		139		—				—


$0.08 - $12.12		2,359,287		7.84	$	26,964		1,273,335		7.12	$	15,788

Schedule of weighted average assumptions used to calculate the fair value of share based payments for option granted to employees and directors estimated on the date of grant using the Black Scholes option pricing valuation model

	Year Ended December 31,

	2013	2012
Expected term (in years)	5.00 - 6.08	5.00 - 6.08
Expected volatility	80.42 - 81.41%	82.07 - 84.33%
Risk-free interest rate	0.88 - 2.11%	0.65 - 1.19%
Dividend yield	—	—

Stock-based Compensation

Stock incentive plans

Summary of share-based compensation expense

	Year Ended December 31,

	2013		2012		2011
Cost of revenue	$	34	$	26	$	32
Research and development		250		131		130
Selling and marketing		169		111		77
General and administrative		794		407		227


Total stock-based compensation expense	$	1,247	$	675	$	466

Equity-based Compensation

Stock incentive plans

Summary of share-based compensation expense

	Year Ended December 31,

	2013		2012		2011
Cost of revenue	$	—	$	2	$	2
Research and development		—		100		80
Selling and marketing		—		39		41
General and administrative		—		118		70


Total equity-based compensation expense	$	—	$	259	$	193

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Income Taxes

Schedule of reconciliation of tax expense computed at the statutory federal rate and the Company's tax expense

The following table presents a reconciliation of the tax expense computed at the statutory federal rate and the Company's tax expense for the period presented (in thousands):

	Year Ended December, 31,

	2013			2012			2011
U.S. federal taxes at statutory rate	$	(8,697	)	$	(6,341	)	$	(4,911	)
State taxes (net of federal benefit)		11			(1,074	)		(843	)
Permanent differences		1,145			261			(108	)
Tax credits		(502	)		(113	)		(181	)
Change in valuation allowance		8,043			7,267			6,043


Total	$	—		$	—		$	—

Schedule of tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets

The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets are as follows (in thousands):

	As of December 31,

	2013			2012			2011
Current deferred tax assets:
Net operating loss carryforwards	$	—		$	—		$	—
Research and development credit		—			—			—
Stock-based compensation		—			—			—
Genzyme co-promotion agreement		1,005			1,001			—
Accruals and deferred rent		599			148			—


Gross deferred tax assets		1,604			1,149			—
Valuation allowance		(1,603	)		(1,145	)		—


Net deferred tax assets		1			4			—


Deferred tax liabilities:
Property and equipment		—			—			—


Gross deferred tax liabilities		—			—			—


Net current deferred tax liabilities		1			4			—


Non-current deferred tax assets:
Net operating loss carryforwards		28,569			20,536			16,547
Research and development credit		1,455			954			723
Stock-based compensation		313			154			50
Genzyme co-promotion agreement		787			2,048			—
Accruals, depreciation and deferred rent		106			9			197


Gross deferred tax assets		31,230			23,701			17,517
Valuation allowance		(31,216	)		(23,622	)		(17,469	)


Net deferred tax assets		14			79			48


Deferred tax liabilities:
Property and equipment		(15	)		(83	)		(48	)


Gross deferred tax liabilities		(15	)		(83	)		(48	)


Net non-current deferred tax liabilities		(1	)		(4	)		—


Total deferred tax assets	$	—		$	—		$	—

Schedule of reconciliation of the beginning and ending amount of unrecognized tax benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):

	Year Ended December 31,

	2013		2012		2011
Unrecognized tax benefits, beginning of period	$	481	$	341	$	263
Gross increases—tax position in prior period		68		67		—
Gross decrease—tax position in prior period		—		—		—
Gross increases—current period tax positions		178		73		78
Lapse of statute of limitations		—		—		—


Unrecognized tax benefits, end of period	$	728	$	481	$	341

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2013

Selected Quarterly Financial Data (Unaudited)

Schedule of selected quarterly financial data (unaudited)

Quarter Ended:	March 31			June 30			September 30			December 31

	(In thousands, except share and per share data)
2013:
Total revenues	$	4,384		$	5,068		$	5,594		$	6,838
Net loss	$	(6,895	)	$	(6,490	)	$	(6,303	)	$	(5,892	)
Net loss per common share, basic and diluted	$	(9.04	)	$	(7.53	)	$	(6.59	)	$	(0.42	)
Shares used in calculation of net loss per share, basic and diluted		763,021			861,839			955,890			13,944,239
2012:
Total revenues	$	1,468		$	2,479		$	3,224		$	4,457
Net loss	$	(4,248	)	$	(4,626	)	$	(4,938	)	$	(4,837	)
Net loss per common share, basic and diluted	$	(6.81	)	$	(7.08	)	$	(7.49	)	$	(7.27	)
Shares used in calculation of net loss per share, basic and diluted		623,515			653,121			659,129			665,306

Organization and Description of Business (Details) $ / shares in Units, $ in Millions				1 Months Ended	12 Months Ended
	Dec. 02, 2013 USD ($) shares	Nov. 04, 2013 $ / shares shares	Oct. 09, 2013 shares	Dec. 02, 2013 USD ($)	Dec. 31, 2013 segment $ / shares shares	Dec. 31, 2012 $ / shares
Organization and Description of Business
Number of operating segments \| segment					1
Reverse Stock Split and Initial Public Offering
Reverse stock split ratio			4
Common stock issued upon conversion of each preferred stock (in shares)			0.25
Number of shares issued and sold in IPO	100,351	5,000,000
Net proceeds from issuance of common stock in IPO \| $				$ 59.2
Underwriting discounts and commissions \| $	$ 4.6			4.6
Offering expenses \| $	$ 2.5			$ 2.5
Common stock issued on automatic conversion of outstanding convertible preferred stock (in shares)		14,997,312
Common stock
Reverse Stock Split and Initial Public Offering
Number of shares issued and sold in IPO					5,100,351
Issuance price per share in IPO (in dollars per share) \| $ / shares		$ 13.00			$ 14.50	$ 4.00
Common stock issued on automatic conversion of outstanding convertible preferred stock (in shares)					14,997,312

Summary of Significant Accounting Policies (Details)	12 Months Ended
Summary of Significant Accounting Policies (Details)	Dec. 31, 2013 USD ($) institution	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)
Concentrations of Credit Risk and Other Risks and Uncertainties
Number of major financial institutions with which the company's cash and cash equivalents are deposited \| institution	1
Restricted Cash
Deposits	$ 118,000	$ 168,000
Letter of credit serving as security for lease	118,000	118,000
Certificate of deposit		50,000
Activity of allowance for doubtful accounts
Beginning balance	222,000	235,000
Charged to expense	109,000	225,000	$ 235,000
Write-offs, net of recoveries	(224,000)	(238,000)
Ending balance	$ 107,000	$ 222,000	$ 235,000
Revenue \| Revenue concentration risk
Concentrations of Credit Risk and Other Risks and Uncertainties
Concentrations of credit risk (as a percent)	59.00%	59.00%
Revenue \| Revenue concentration risk \| Medicare
Concentrations of Credit Risk and Other Risks and Uncertainties
Concentrations of credit risk (as a percent)	32.00%	34.00%
Revenue \| Revenue concentration risk \| Aetna
Concentrations of Credit Risk and Other Risks and Uncertainties
Concentrations of credit risk (as a percent)	9.00%	13.00%
Revenue \| Revenue concentration risk \| United Healthcare
Concentrations of Credit Risk and Other Risks and Uncertainties
Concentrations of credit risk (as a percent)	18.00%	12.00%
Accounts receivable \| Gross receivables concentration risk \| Medicare
Concentrations of Credit Risk and Other Risks and Uncertainties
Concentrations of credit risk (as a percent)	78.00%	87.00%

Summary of Significant Accounting Policies (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Property and Equipment and Internal-use Software
Total cost	$ 5,767,000	$ 4,262,000
Accumulated depreciation	2,815,000	1,816,000
Net book value	$ 2,952,000	2,446,000
Minimum
Property and Equipment and Internal-use Software
Estimated useful life	3 years
Maximum
Property and Equipment and Internal-use Software
Estimated useful life	5 years
Capitalized software
Property and Equipment and Internal-use Software
Estimated useful life	3 years
Capitalized costs	$ 212,000	173,000
Amortization expense	108,000	47,000
Total cost	482,000	271,000
Accumulated depreciation	195,000	87,000
Net book value	$ 287,000	$ 184,000

Summary of Significant Accounting Policies (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Long-lived Assets
Impairments	$ 215
Bonus Accruals
Accrued liabilities associated with employee and executive bonus plans		$ 1,100	$ 700

Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Calculation of basic and diluted net loss per common share
Net loss									$ (25,580)	$ (18,649)	$ (14,445)
Shares used to compute net loss per common share, basic and diluted (in shares)	13,944,239	955,890	861,839	763,021	665,306	659,129	653,121	623,515	4,158,664	650,333	580,061
Net loss per common share, basic and diluted (in dollars per share)	$ (0.42)	$ (6.59)	$ (7.53)	$ (9.04)	$ (7.27)	$ (7.49)	$ (7.08)	$ (6.81)	$ (6.15)	$ (28.68)	$ (24.90)
Outstanding shares of common stock equivalents that have been excluded from diluted net loss per common share
Total shares of common stock equivalents (in shares)									2,384,088	15,498,791
Shares of common stock subject to outstanding options
Outstanding shares of common stock equivalents that have been excluded from diluted net loss per common share
Total shares of common stock equivalents (in shares)									2,359,287	2,227,669
Shares of common stock issuable upon conversion of preferred stock
Outstanding shares of common stock equivalents that have been excluded from diluted net loss per common share
Total shares of common stock equivalents (in shares)										13,271,122
Shares of common stock issuable upon exercise of warrants
Outstanding shares of common stock equivalents that have been excluded from diluted net loss per common share
Total shares of common stock equivalents (in shares)									24,801

Balance Sheet Components (Details) - USD ($) $ in Thousands	12 Months Ended
Balance Sheet Components (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property and Equipment, Net
Total property and equipment, at cost	$ 5,767	$ 4,262
Accumulated depreciation and amortization	(2,815)	(1,816)
Total property and equipment, net	2,952	2,446
Depreciation and amortization expense	999	706	$ 611
Cost of revenue
Property and Equipment, Net
Depreciation and amortization expense	593	401	397
Research and development
Property and Equipment, Net
Depreciation and amortization expense	179	184	162
Selling and marketing
Property and Equipment, Net
Depreciation and amortization expense	54	46	21
General and administrative
Property and Equipment, Net
Depreciation and amortization expense	173	75	$ 31
Leasehold improvements
Property and Equipment, Net
Total property and equipment, at cost	779	341
Laboratory equipment
Property and Equipment, Net
Total property and equipment, at cost	2,946	2,061
Computer equipment
Property and Equipment, Net
Total property and equipment, at cost	645	526
Software, including software developed for internal use
Property and Equipment, Net
Total property and equipment, at cost	901	554
Furniture and fixtures
Property and Equipment, Net
Total property and equipment, at cost	189	81
Construction-in-process
Property and Equipment, Net
Total property and equipment, at cost	$ 307	$ 699

Balance Sheet Components (Details 2) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Accrued Liabilities
Accrued compensation expenses (in dollars)	$ 1,962	$ 1,360
Accrued consulting fees	7	28
Accrued legal and professional fees	62	84
Accrued other	562	373
Accrued Genzyme co-promotion fees	4,915	2,175
Deferred rent-short-term	86
Total accrued liabilities	$ 7,594	$ 4,020

Fair Value Measurements (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Level I
Fair value measurements
Financial Assets	$ 69,972	$ 12,830
Level I \| Money market funds
Fair value measurements
Financial Assets	69,972	12,830
Level III
Fair value measurements
Financial Liabilities		583
Level III \| Preferred stock liability
Fair value measurements
Financial Liabilities		583
Total
Fair value measurements
Financial Assets	69,972	12,830
Financial Liabilities		583
Total \| Preferred stock liability
Fair value measurements
Financial Liabilities		583
Total \| Money market funds
Fair value measurements
Financial Assets	$ 69,972	$ 12,830

Fair Value Measurements (Details 2) - USD ($)	1 Months Ended	12 Months Ended
Fair Value Measurements (Details 2) - USD ($)	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Changes in the fair value of the Company's Level 3 financial liabilities
Beginning balance		$ 583,000
Ending balance			$ 583,000
Preferred stock liability
Changes in the fair value of the Company's Level 3 financial liabilities
Settlement of preferred stock liability	$ 2,700,000
Recurring \| Level 3 \| Preferred stock liability
Changes in the fair value of the Company's Level 3 financial liabilities
Fair value of liability			861,000
Change in fair value of preferred stock liability recorded as other expense, net		2,070,000	$ (278,000)
Settlement of preferred stock liability		2,653,000
Recurring \| Level 3 \| Preferred stock warrant liability
Changes in the fair value of the Company's Level 3 financial liabilities
Fair value of liability		175,000
Change in fair value of preferred stock liability recorded as other expense, net		86,000
Conversion of preferred stock warrant liability		$ 261,000

Fair Value Measurements (Details 3) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jun. 17, 2013	Nov. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Nov. 03, 2013	Jun. 30, 2013
Fair value measurements
Fair value of liability				$ 583
Change in value of preferred stock liability			$ 2,070	(278)	$ (719)
Series C convertible preferred stock
Assumptions used to calculate fair value of preferred stock liability using the option-pricing method
Fair value of preferred stock (in dollars per share)	$ 2.39	$ 1.78				$ 13.14	$ 2.40
Preferred stock liability
Fair value measurements
Fair value of liability	$ 2,700	$ 900		600
Change in value of preferred stock liability	$ 2,100			$ (300)
Assumptions used to calculate fair value of preferred stock liability using the option-pricing method
Probability of success of the second tranche (as a percent)	100.00%	100.00%
Term	1 day	8 months 1 day
Expected volatility (as a percent)	36.40%	44.00%

Genzyme Co-promotion Agreement (Details)		1 Months Ended		12 Months Ended
Genzyme Co-promotion Agreement (Details)	Mar. 01, 2014	Feb. 29, 2012 USD ($)	May 31, 2011 USD ($)	Dec. 31, 2013 USD ($) country	Dec. 31, 2012 USD ($)	Jan. 31, 2012 country
Genzyme Co-promotion Agreement
Amount received from Genzyme in connection with an extension of an exclusive right to negotiate co-promotion agreement			$ 100,000
Co-promotion fee received from Genzyme					$ 10,000,000
Amortization of up-front co-promotion fee				$ 2,500,000	2,386,000
Unamortized balance of the co-promotion fee
Deferred Genzyme co-promotion fee				2,500,000	2,500,000
Deferred Genzyme co-promotion fee, net of current portion				2,614,000	5,114,000
Co-promotion agreement
Genzyme Co-promotion Agreement
Number of countries outside United States in which marketing authorization is obtained \| country						40
Co-promotion fee received from Genzyme		$ 10,000,000
Additional payments that may be received				3,000,000
Additional payments that may be received for each country outside of the United States in which the company obtains marketing authorization and achieves a specified level of reimbursement				$ 600,000
Prior notice period for termination of agreement				6 months
Amortization period of co-promotion fee				4 years
Co-promotion expenses				$ 8,600,000	5,500,000
Amortization of up-front co-promotion fee				2,500,000	2,400,000
Unamortized balance of the co-promotion fee
Deferred Genzyme co-promotion fee				2,500,000	2,500,000
Deferred Genzyme co-promotion fee, net of current portion				2,614,000	5,114,000
Total				$ 5,114,000	$ 7,614,000
Co-promotion agreement \| Maximum
Genzyme Co-promotion Agreement
Number of countries outside United States for which additional payments may be received \| country				5
Co-promotion agreement \| Genzyme
Genzyme Co-promotion Agreement
Percentage of cash receipts of co-promotion fees received by co-promoter				40.00%	50.00%
Percentage of cash receipts of co-promotion fees received by co-promoter for remaining periods	32.00%
Maximum amount to be spent by co-promoter for qualifying clinical development activities in countries that require additional testing				$ 500,000

Thyroid Cytopathology Partners (Details) - USD ($)	12 Months Ended
Thyroid Cytopathology Partners (Details) - USD ($)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Thyroid Cytopathology Partners
Outstanding obligations	$ 5,294,000	$ 1,888,000
Thyroid Cytopathology Partners
Thyroid Cytopathology Partners
Expenses for cytopathology testing and evaluation services	3,200,000	1,800,000	$ 434,000
Professional licensure fees paid to TCP		137,000	$ 83,000
Outstanding obligations	588,000	$ 458,000
Reduction to rent expense for TCP's portion of costs for shared space	49,000
Reimbursed rent	59,000
Excess payment included in accounts payable	$ 10,000

Commitments and Contingencies (Details) - USD ($)	12 Months Ended
Commitments and Contingencies (Details) - USD ($)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating Leases
Restricted cash	$ 118,000	$ 118,000
Cash security deposit	75,000	75,000
Future minimum lease payments under non-cancelable operating leases
2014	938,000
2015	989,000
2016	413,000
2017	222,000
2018	130,000
Total minimum lease payments	2,692,000
Facilities rent expense	840,000	$ 711,000	$ 570,000
Volume Purchase Agreement
Non-cancelable purchase obligations to contract manufacturers and suppliers	250,000
Estimated amount payable in 2014	125,000
Estimated amount payable in 2015	125,000
Maximum
Operating Leases
Tenant improvement allowances	$ 253,000

Debt (Details)	6 Months Ended	12 Months Ended
Debt (Details)	Jun. 30, 2013 USD ($) installment $ / shares shares	Dec. 31, 2013 USD ($)	Nov. 03, 2013 USD ($)	Dec. 31, 2012 USD ($)
Debt
Amount drawn down	$ 5,000,000
Aggregate fair value of the warrant for the shares exercisable under the warrant				$ 583,000
Interest on the debt		$ 42,000
Amortization of debt discount and accretion		56,000
Convertible Preferred Stock Warrant
Debt
Exercise price of warrant to purchase shares of Series C convertible preferred stock (in dollars per share) \| $ / shares	7.56
Number of shares for which warrant became exercisable \| shares	24,801
Aggregate fair value of the warrant for the shares exercisable under the warrant	$ 175,000		$ 261,000
Loan and security agreement
Debt
Maximum borrowing capacity	10,000,000
Borrowing capacity available for second term loan		5,000,000
Term loan
Debt
Amount drawn down	$ 5,000,000
Number of installments \| installment	30
Period after which debt is repayable	18 months
Interest rate (as a percent)	6.06%
Prepayment penalties for prepayment within one year of the loan origination (as a percent)	2.25%
Prepayment penalties for prepayment within two years of the loan origination (as a percent)	1.50%
Prepayment penalties for prepayment after two years of the loan origination (as a percent)	0.75%
Amortization period of debt discount	48 months
Amount of end of term payment	$ 223,000
End of term payment as a percentage of total outstanding principal balance	4.45%
Interest on the debt		233,000
Amortization of debt discount and accretion		75,000
Nominal interest on the debt excluding amortization of debt discount and accretion		$ 158,000

Convertible Preferred Stock Warrants (Details) - USD ($)			1 Months Ended	12 Months Ended
	Mar. 17, 2014	Nov. 03, 2013	Jun. 30, 2013	Dec. 31, 2013	Nov. 04, 2013	Jun. 17, 2013	Dec. 31, 2012	Nov. 30, 2012
Convertible preferred stock warrant
Amount drawn down of term loan			$ 5,000,000
Fair value of currently exercisable portion of the warrant							$ 583,000
Assumptions used to calculate fair value of warrant upon issuance using Black-Scholes option-pricing valuation model
Amount of change in the fair value reported as an expense in other income (expense), net				$ 86,000
Common Stock
Assumptions used to calculate fair value of warrant upon issuance using Black-Scholes option-pricing valuation model
Fair value of preferred stock (in dollars per share)				$ 14.50	$ 13.00		$ 4.00
Subsequent Events \| Common Stock
Assumptions used to calculate fair value of warrant upon issuance using Black-Scholes option-pricing valuation model
Issuance of common stock on exercise of warrant (in shares)	13,739
Series C convertible preferred stock
Convertible preferred stock warrant
Issuance of convertible preferred stock, issue price (in dollars per share)			$ 1.89				$ 1.89	$ 1.89
Assumptions used to calculate fair value of warrant upon issuance using Black-Scholes option-pricing valuation model
Fair value of preferred stock (in dollars per share)		$ 13.14	$ 2.40			$ 2.39		$ 1.78
Convertible Preferred Stock Warrant
Convertible preferred stock warrant
Number of shares of preferred stock that can be purchased by each warrant			49,602
Issuance of convertible preferred stock, issue price (in dollars per share)			$ 7.56
Number of shares for which warrant became exercisable			24,801
Remaining number of shares for which warrant may become exercisable			24,801
Exercise price of warrants in the event of conversion of outstanding Series C convertible preferred stock into common stock (in dollars per share)			7.56
Fair value of currently exercisable portion of the warrant		$ 261,000	$ 175,000
Assumptions used to calculate fair value of warrant upon issuance using Black-Scholes option-pricing valuation model
Contractual term		7 years	7 years 3 months 18 days
Risk-free interest rate (as a percent)		2.00%	2.10%
Expected volatility (as a percent)		81.40%	73.70%
Expected dividend yield (as a percent)		0.00%	0.00%
Amount of change in the fair value reported as an expense in other income (expense), net				$ 86,000
Convertible Preferred Stock Warrant \| Maximum
Convertible preferred stock warrant
Warrant term			7 years
Common Stock Warrants
Convertible preferred stock warrant
Number of shares for which warrant became exercisable					24,801
Aggregate number of shares for which warrant becomes exercisable if Company draws down second term loan (in shares)					49,602
Exercise price of warrants in the event of conversion of outstanding Series C convertible preferred stock into common stock (in dollars per share)					7.56

Convertible Preferred Stock (Details) $ / shares in Units, $ in Thousands			1 Months Ended		2 Months Ended	12 Months Ended
	Nov. 04, 2013 $ / shares shares	Jun. 17, 2013 USD ($) $ / shares	Jun. 30, 2013 USD ($) closing $ / shares shares	Nov. 30, 2012 USD ($) closing $ / shares shares	Dec. 31, 2012 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares	Dec. 31, 2012 USD ($) $ / shares shares	Dec. 31, 2011 USD ($)	Nov. 03, 2013 $ / shares	Jul. 31, 2011 $ / shares	Feb. 28, 2011 $ / shares
Convertible preferred stock
Convertible preferred stock converted to common stock (in shares)	59,989,268
Common stock issued on automatic conversion of outstanding convertible preferred stock (in shares)	14,997,312
Preferred stock, shares authorized	5,000,000				0	5,000,000	0
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.001				$ 0.001	$ 0.001	$ 0.001
Shares Authorized					59,147,999	0	59,147,999
Shares Issued					53,084,507	0	53,084,507
Shares Outstanding					53,084,507	0	53,084,507
Aggregate Liquidation Amount \| $					$ 65,835	$ 0	$ 65,835
Proceeds Net of Issuance Costs and Preferred Stock Liability \| $							63,372
Gross proceeds from issuance of shares \| $						12,945	14,989	$ 18,622
Assumptions used to calculate fair value of preferred stock liability using the option-pricing method
Preferred stock liability \| $					583		583
Preferred stock liability valuation decrease recorded in other income (expense), net \| $						$ (2,070)	278	$ 719
Preferred stock liability
Assumptions used to calculate fair value of preferred stock liability using the option-pricing method
Probability of success of the second tranche (as a percent)		100.00%		100.00%
Contractual term		1 day		8 months 1 day
Expected volatility (as a percent)		36.40%		44.00%
Preferred stock liability \| $		$ 2,700		$ 900	$ 600		600
Preferred stock liability valuation decrease recorded in other income (expense), net \| $		$ (2,100)					$ 300
Preferred stock liability settled \| $			$ (2,700)
Series A
Convertible preferred stock
Shares Authorized					22,399,999		22,399,999
Original Issue Price (in dollars per share) \| $ / shares					$ 1.00		$ 1.00
Shares Issued					22,399,999		22,399,999
Shares Outstanding					22,399,999		22,399,999
Aggregate Liquidation Amount \| $					$ 22,400		$ 22,400
Proceeds Net of Issuance Costs and Preferred Stock Liability \| $							$ 22,328
Series B
Convertible preferred stock
Shares Authorized					22,748,000		22,748,000
Original Issue Price (in dollars per share) \| $ / shares					$ 1.25		$ 1.25			$ 1.25	$ 1.25
Shares Issued					22,748,000		22,748,000
Shares Outstanding					22,748,000		22,748,000
Aggregate Liquidation Amount \| $					$ 28,435		$ 28,435
Proceeds Net of Issuance Costs and Preferred Stock Liability \| $							$ 26,968
Series C
Convertible preferred stock
Shares Authorized			14,852,001		14,000,000		14,000,000
Original Issue Price (in dollars per share) \| $ / shares			$ 1.89	$ 1.89	$ 1.89		$ 1.89
Shares Issued					7,936,508		7,936,508
Shares Outstanding					7,936,508		7,936,508
Aggregate Liquidation Amount \| $					$ 15,000		$ 15,000
Proceeds Net of Issuance Costs and Preferred Stock Liability \| $							$ 14,076
Shares authorized to be issued and sold				13,227,513
Number of closings \| closing				3
Number of shares that may be sold in initial purchase				7,910,053
Number of shares that may be sold in second closing				5,291,005
Number of shares that may be sold in additional closing			1,640,212	26,455
Number of additional closings \| closing			2
Gross proceeds from issuance of shares \| $			$ 13,000		$ 15,000
Number of shares issued			6,904,761		7,936,508
Assumptions used to calculate fair value of preferred stock liability using the option-pricing method
Fair value of preferred stock (in dollars per share) \| $ / shares		$ 2.39	$ 2.40	$ 1.78					$ 13.14

Stockholders' Equity (Deficit) (Details)	12 Months Ended
Stockholders' Equity (Deficit) (Details)	Dec. 31, 2013 USD ($) vote $ / shares shares	Nov. 04, 2013 $ / shares shares	Dec. 31, 2012 $ / shares shares	Dec. 31, 2011 shares
Stockholders' Equity (Deficit)
Authorized shares of common stock	125,000,000		77,000,000
Par value of shares of common stock (in dollars per share) \| $ / shares	$ 0.001		$ 0.001
Number of votes for each share of stock \| vote	1
Dividends declared \| $	$ 0
Common Stock
Options issued and outstanding (in shares)	2,359,287		2,227,669	1,429,737
Options available for grant under stock option plans (in shares)	1,787,802		347,386	474,961
Shares of common stock reserved for issuance	4,171,890		17,168,928
Preferred stock, shares authorized	5,000,000	5,000,000	0
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0
Options
Common Stock
Options issued and outstanding (in shares)	2,359,287		2,227,669
Options available for grant under stock option plans (in shares)	1,787,802		347,386
Common Stock Warrants
Common Stock
Common stock warrants issued and outstanding (in shares)	24,801
Series A convertible preferred stock
Common Stock
Conversion of convertible preferred stock (in shares)			5,599,999
Series B convertible preferred stock
Common Stock
Conversion of convertible preferred stock (in shares)			5,686,999
Series C convertible preferred stock
Common Stock
Conversion of convertible preferred stock (in shares)			1,984,124
Conversion of convertible preferred stock reserved for issuance (in shares)			1,322,751

Stock Incentive Plans (Details) - shares	Oct. 02, 2013	Feb. 15, 2008	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock incentive plans
Number of shares available for issuance			1,787,802	347,386	474,961
Options
Stock incentive plans
Number of shares available for issuance			1,787,802	347,386
2008 Plan \| Options \| Minimum
Stock incentive plans
Exercise price of options granted expressed as a percentage of its fair value		100.00%
2008 Plan \| Options \| Maximum
Stock incentive plans
Term of options granted		10 years
2008 Plan \| Options \| Newly hired employee
Stock incentive plans
Vesting period		4 years
Percentage of award vesting after one year		25.00%
2008 Plan \| ISO \| Minimum
Stock incentive plans
Voting power of person owning stock (as a percent)		10.00%
Option price as a percentage of estimated fair value of shares on date of grant to a person owning stock representing more than 10% of voting power of all classes of stock		110.00%
2008 Plan \| ISO \| Maximum
Stock incentive plans
Term of options granted to a person owning stock representing more than 10% of voting power of all classes of stock		5 years
2013 Plan
Stock incentive plans
Number of additional shares reserved for issuance	1,700,000
Number of shares available for issuance			1,787,802
Maximum annual increase in outstanding shares on the last day of the immediately preceding fiscal year (as a percent)	4.00%
2013 Plan \| Options \| Outside director serving as a member of Board of Directors for at least six months
Stock incentive plans
Shares granted as annual grant	10,000
2013 Plan \| Options \| Outside director serving as a member of Board of Directors for at least six months \| Minimum
Stock incentive plans
Period for which director has to serve as board of director to receive grant to purchase shares	6 months
2013 Plan \| Options \| Outside director
Stock incentive plans
Exercise price of options granted expressed as a percentage of its fair value	100.00%
2013 Plan \| Options \| Outside director \| Maximum
Stock incentive plans
Term of options granted	10 years
Expiration period after termination of service	12 months
2013 Plan \| ISO \| Minimum
Stock incentive plans
Exercise price of options granted expressed as a percentage of its fair value	100.00%
2013 Plan \| ISO \| Maximum
Stock incentive plans
Term of options granted	10 years
2013 Plan \| NSO \| Minimum
Stock incentive plans
Exercise price of options granted expressed as a percentage of its fair value	100.00%
2013 Plan \| NSO \| Outside director who was not previously an employee
Stock incentive plans
Percentage of award vesting after one year	25.00%
Shares granted as initial grant	35,000
Percentage of award granted which vests on a monthly basis	0.75
Period over which remaining shares will vest on a monthly basis	3 years

Stock Incentive Plans (Details 2) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Shares Available for Grant
Balances at the beginning of the period (in shares)	347,386	474,961
Additional options authorized (in shares)	1,950,000	743,100
Granted (in shares)	(695,029)	(931,944)
Canceled (in shares)	185,445	61,269
Balances at the end of the period (in shares)	1,787,802	347,386	474,961
Stock Options Outstanding
Balances at beginning of the period (in shares)	2,227,669	1,429,737
Granted (in shares)	695,029	931,944
Canceled (in shares)	(185,445)	(61,269)
Exercised (in shares)	(377,966)	(72,743)
Balances at the end of the period (in shares)	2,359,287	2,227,669	1,429,737
Options exercisable at the end of the period (in shares)	1,273,335
Options vested and expected to vest at the end of the period (in shares)	2,250,293
Weighted Average Exercise Price
Balances at beginning of the period (in dollars per share)	$ 2.06	$ 1.55
Granted (in dollars per share)	5.32	2.78
Canceled (in dollars per share)	2.69	1.97
Exercised (in dollars per share)	1.46	1.05
Balances at the end of the period (in dollars per share)	3.07	$ 2.06	$ 1.55
Options exercisable at the end of the period (in dollars per share)	2.10
Options vested and expected to vest at the end of the period (in dollars per share)	$ 3.02
Weighted Average Remaining Contractual Life
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	7 years 10 months 2 days	8 years 2 months 1 day	8 years 2 months 19 days
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	7 years 10 months 2 days	8 years 2 months 1 day	8 years 2 months 19 days
Options exercisable at the end of the period	7 years 1 month 13 days
Options vested and expected to vest at the end of the period	7 years 9 months 18 days
Aggregate Intrinsic Value
Balances at the beginning of the period (in dollars)	$ 4,311	$ 1,221
Balances at the end of the period (in dollars)	26,964	$ 4,311	$ 1,221
Options exercisable at the end of the period (in dollars)	15,788
Options vested and expected to vest at the end of the period (in dollars)	$ 25,842

Stock Incentive Plans (Details 3) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Outstanding and exercisable stock options
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 26,964	$ 4,311	$ 1,221
Options Vested and Exercisable, Aggregate Intrinsic Value (in dollars)	$ 15,788
$0.08
Outstanding and exercisable stock options
Exercise price (in dollars per share)	$ 0.08
Options Outstanding, Number of Options Outstanding	177,750
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 7 months 20 days
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 2,563
Options Vested and Exercisable, Number of Options Exercisable (in shares)	177,750
Options Vested and Exercisable, Weighted Average Remaining Contractual Life	4 years 7 months 20 days
Options Vested and Exercisable, Aggregate Intrinsic Value (in dollars)	$ 2,563
$0.80
Outstanding and exercisable stock options
Exercise price (in dollars per share)	$ 0.80
Options Outstanding, Number of Options Outstanding	165,569
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 1 month 20 days
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 2,268
Options Vested and Exercisable, Number of Options Exercisable (in shares)	158,458
Options Vested and Exercisable, Weighted Average Remaining Contractual Life	6 years 1 month 17 days
Options Vested and Exercisable, Aggregate Intrinsic Value (in dollars)	$ 2,171
$2.36
Outstanding and exercisable stock options
Exercise price (in dollars per share)	$ 2.36
Options Outstanding, Number of Options Outstanding	414,874
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 9 months 22 days
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 5,037
Options Vested and Exercisable, Number of Options Exercisable (in shares)	340,023
Options Vested and Exercisable, Weighted Average Remaining Contractual Life	6 years 9 months 22 days
Options Vested and Exercisable, Aggregate Intrinsic Value (in dollars)	$ 4,128
$2.40
Outstanding and exercisable stock options
Exercise price (in dollars per share)	$ 2.40
Options Outstanding, Number of Options Outstanding	208,593
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 8 months 5 days
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 2,524
Options Vested and Exercisable, Number of Options Exercisable (in shares)	147,299
Options Vested and Exercisable, Weighted Average Remaining Contractual Life	7 years 8 months 8 days
Options Vested and Exercisable, Aggregate Intrinsic Value (in dollars)	$ 1,782
$2.68
Outstanding and exercisable stock options
Exercise price (in dollars per share)	$ 2.68
Options Outstanding, Number of Options Outstanding	653,952
Options Outstanding, Weighted Average Remaining Contractual Life	8 years 3 months 11 days
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 7,730
Options Vested and Exercisable, Number of Options Exercisable (in shares)	319,005
Options Vested and Exercisable, Weighted Average Remaining Contractual Life	8 years 3 months 4 days
Options Vested and Exercisable, Aggregate Intrinsic Value (in dollars)	$ 3,771
$4.00
Outstanding and exercisable stock options
Exercise price (in dollars per share)	$ 4.00
Options Outstanding, Number of Options Outstanding	473,299
Options Outstanding, Weighted Average Remaining Contractual Life	9 years 29 days
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 4,970
Options Vested and Exercisable, Number of Options Exercisable (in shares)	130,800
Options Vested and Exercisable, Weighted Average Remaining Contractual Life	9 years 22 days
Options Vested and Exercisable, Aggregate Intrinsic Value (in dollars)	$ 1,373
$6.04
Outstanding and exercisable stock options
Exercise price (in dollars per share)	$ 6.04
Options Outstanding, Number of Options Outstanding	197,875
Options Outstanding, Weighted Average Remaining Contractual Life	9 years 5 months 19 days
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 1,674
$7.92
Outstanding and exercisable stock options
Exercise price (in dollars per share)	$ 7.92
Options Outstanding, Number of Options Outstanding	9,000
Options Outstanding, Weighted Average Remaining Contractual Life	9 years 8 months 8 days
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 59
$12.12
Outstanding and exercisable stock options
Exercise price (in dollars per share)	$ 12.12
Options Outstanding, Number of Options Outstanding	58,375
Options Outstanding, Weighted Average Remaining Contractual Life	9 years 9 months
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 139
$0.08-$12.12
Outstanding and exercisable stock options
Exercise price, low end of range (in dollars per share)	$ 0.08
Exercise price, high end of range (in dollars per share)	$ 12.12
Options Outstanding, Number of Options Outstanding	2,359,287
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 10 months 2 days
Options Outstanding, Aggregate Intrinsic Value (in dollars)	$ 26,964
Options Vested and Exercisable, Number of Options Exercisable (in shares)	1,273,335
Options Vested and Exercisable, Weighted Average Remaining Contractual Life	7 years 1 month 13 days
Options Vested and Exercisable, Aggregate Intrinsic Value (in dollars)	$ 15,788

Stock Incentive Plans (Details 4) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Nov. 04, 2013
Stock Incentive Plans
Weighted average fair value of options to purchase common stock granted (in dollars per share)	$ 4.19	$ 1.95
Weighted average fair value of options to purchase common stock vested (in dollars per share)	2.12	1.40
Stock incentive plans
Weighted average fair value of stock options exercised (in dollars per share)	$ 0.97	$ 0.88
Intrinsic value of stock options exercised (in dollars)	$ 4.9	$ 0.2
Common stock
Stock incentive plans
Fair market value of common stock (in dollars per share)	$ 14.50	$ 4.00	$ 13.00
Employee stock options
Stock incentive plans
Total estimated grant date fair value of options to purchase common stock vested (in dollars)	$ 1.3	$ 0.6

Stock Incentive Plans (Details 5) - USD ($)	1 Months Ended		12 Months Ended
Stock Incentive Plans (Details 5) - USD ($)	Feb. 28, 2013	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Dividend yield (as a percent)			0.00%	0.00%
Contractual term			7 years 1 month 13 days
Accrued compensation expenses (in dollars)			$ 1,962,000	$ 1,360,000
Options granted (in shares)			695,029	931,944
Fair value (in dollars per share)			$ 2.12	$ 1.40
Option exercise strike price (in dollars per share)			$ 5.32	$ 2.78
Stock-based Compensation, employees and directors
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Expected volatility, low end of range (as a percent)			80.42%	82.07%
Expected volatility, high end of range (as a percent)			81.41%	84.33%
Risk-free interest rate, low end of range (as a percent)			0.88%	0.65%
Risk-free interest rate, high end of range (as a percent)			2.11%	1.19%
Stock-based Compensation, employees and directors \| Minimum
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Expected term			5 years	5 years
Stock-based Compensation, employees and directors \| Maximum
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Expected term			6 years 29 days	6 years 29 days
Stock-based Compensation, non-employees
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Dividend yield (as a percent)			0.00%	0.00%
Expected volatility, low end of range (as a percent)			77.86%	81.14%
Expected volatility, high end of range (as a percent)			78.14%	82.11%
Risk-free interest rate, low end of range (as a percent)			2.59%	1.43%
Risk-free interest rate, high end of range (as a percent)			2.99%	1.77%
Stock-based Compensation, non-employees \| Minimum
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Contractual term			7 years 8 months 19 days	8 years 2 months 23 days
Stock-based Compensation, non-employees \| Maximum
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Contractual term			9 years 9 months	9 years 11 months 5 days
Equity-based Compensation, executive bonuses
Assumptions used to calculate estimated fair value of stock options using the Black-Scholes option-pricing valuation model
Dividend yield (as a percent)	0.00%	0.00%
Expected term	5 years	5 years
Expected volatility (as a percent)	81.41%	83.52%
Risk-free interest rate (as a percent)	0.88%	0.88%
Accrued compensation expenses (in dollars)				$ 259,000	$ 193,000
Options granted (in shares)	100,498	109,653
Fair value (in dollars per share)	$ 2.59	$ 1.76
Share-based compensation expense (in dollars)				$ 259,000	$ 193,000
Option exercise strike price (in dollars per share)	$ 4.00	$ 2.68

Stock Incentive Plans (Details 6) - USD ($) $ in Thousands	12 Months Ended
Stock Incentive Plans (Details 6) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock-based Compensation
Stock-based compensation
Share-based compensation expense (in dollars)	$ 1,247	$ 675	$ 466
Unrecognized compensation expense	$ 2,700
Period over which unrecognized compensation expense expected to be recognized	2 years 10 months 24 days
Stock-based Compensation \| Cost of revenue
Stock-based compensation
Share-based compensation expense (in dollars)	$ 34	26	32
Stock-based Compensation \| Research and development
Stock-based compensation
Share-based compensation expense (in dollars)	250	131	130
Stock-based Compensation \| Selling and marketing
Stock-based compensation
Share-based compensation expense (in dollars)	169	111	77
Stock-based Compensation \| General and administrative
Stock-based compensation
Share-based compensation expense (in dollars)	$ 794	407	227
Equity-based Compensation
Stock-based compensation
Share-based compensation expense (in dollars)		259	193
Equity-based Compensation \| Cost of revenue
Stock-based compensation
Share-based compensation expense (in dollars)		2	2
Equity-based Compensation \| Research and development
Stock-based compensation
Share-based compensation expense (in dollars)		100	80
Equity-based Compensation \| Selling and marketing
Stock-based compensation
Share-based compensation expense (in dollars)		39	41
Equity-based Compensation \| General and administrative
Stock-based compensation
Share-based compensation expense (in dollars)		$ 118	$ 70

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes
Pretax loss	$ 25,600	$ 18,600	$ 14,400
Reconciliation of tax expense computed at the statutory federal rate and the Company's tax expense
U.S. federal taxes at statutory rate	(8,697)	(6,341)	(4,911)
State taxes (net of federal benefit)	11	(1,074)	(843)
Permanent differences	1,145	261	(108)
Tax credits	(502)	(113)	(181)
Change in valuation allowance	8,043	7,267	6,043
Current deferred tax assets:
Genzyme co-promotion agreement	1,005	1,001
Accruals and deferred rent	599	148
Gross deferred tax assets	1,604	1,149
Valuation allowance	(1,603)	(1,145)
Net deferred tax assets	1	4
Deferred tax liabilities:
Net current deferred tax assets (liabilities)	1	4
Non-current deferred tax assets:
Net operating loss carryforwards	28,569	20,536	16,547
Research and development credit	1,455	954	723
Stock-based compensation	313	154	50
Genzyme co-promotion agreement	787	2,048
Accruals, depreciation and deferred rent	106	9	197
Gross deferred tax assets	31,230	23,701	17,517
Valuation allowance	(31,216)	(23,622)	(17,469)
Net current deferred tax liabilities	14	79	48
Deferred tax liabilities:
Property and equipment	(15)	(83)	(48)
Gross deferred tax liabilities	(15)	(83)	$ (48)
Net non-current deferred tax liabilities	(1)	(4)
Cumulative excess tax benefits from stock option deduction	300
Increase in valuation allowance against deferred tax assets	8,100	$ 7,300
Federal
Operating loss carryforwards
Net operating loss carryforwards	75,100
State
Operating loss carryforwards
Net operating loss carryforwards	$ 54,000

Income Taxes (Details 2) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details 2) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Unrecognized tax benefits, beginning of period	$ 481	$ 341	$ 263
Gross increases-tax position in prior period	68	67
Gross increases-current period tax positions	178	73	78
Unrecognized tax benefits, end of period	728	$ 481	$ 341
Interest expense or penalties related to unrecognized tax benefits	0
Federal
Credit carryforwards
Credit carryforwards available to reduce future taxable income	1,400
State
Credit carryforwards
Credit carryforwards available to reduce future taxable income	$ 1,000

Income Taxes (Details 3)	12 Months Ended
Income Taxes (Details 3)	Dec. 31, 2013
Federal
Income tax examination
Income tax examination period	3 years
State
Income tax examination
Income tax examination period	4 years

401(k) Plan (Details) - USD ($)	12 Months Ended
401(k) Plan (Details) - USD ($)	Dec. 31, 2013	Dec. 31, 2012
401(k) Plan
Employer contributions to the plan	$ 0	$ 0

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Selected Quarterly Financial Data (Unaudited)
Total revenues	$ 6,838	$ 5,594	$ 5,068	$ 4,384	$ 4,457	$ 3,224	$ 2,479	$ 1,468	$ 21,884	$ 11,628	$ 2,645
Net loss	$ (5,892)	$ (6,303)	$ (6,490)	$ (6,895)	$ (4,837)	$ (4,938)	$ (4,626)	$ (4,248)
Net loss per common share, basic and diluted	$ (0.42)	$ (6.59)	$ (7.53)	$ (9.04)	$ (7.27)	$ (7.49)	$ (7.08)	$ (6.81)	$ (6.15)	$ (28.68)	$ (24.90)
Shares used in calculation of net loss per share, basic and diluted	13,944,239	955,890	861,839	763,021	665,306	659,129	653,121	623,515	4,158,664	650,333	580,061

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Net Income
-URI http://asc.fasb.org/extlink&oid=6518256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.18)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.22)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Other Comprehensive Income
-URI http://asc.fasb.org/extlink&oid=6519514

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e565-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 20
-Article 9

+ Details