Stock Option Plans (Tables)

6 Months Ended

Jun. 30, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Option Activity and Related Information

The following table summarizes option activity and related information during the six months ended June 30, 2014 under the 2008 Equity Incentive Plan and for options which remain outstanding under the 1998 Stock Plan:

	Shares Available for Grant			Options Outstanding
				Number of Shares			Weighted- average Exercise Price
Balance at December 31, 2013		332,995			466,965		$	1.99
Increase in shares reserved for issuance		102,189			—		$	—
Granted		(461,795	)		461,795		$	12.40
Exercised		—			(2,199	)	$	2.56
Forfeited		14,532			(14,532	)	$	10.46
Expired		12,079			(12,079	)	$	2.96
Balance at June 30, 2014		—			899,950		$	7.22

Summary of Options Outstanding and Exercisable Vested and Expected to Vest

Options outstanding and exercisable that have vested and are expected to vest at June 30, 2014 are as follows:

	Number of Shares		Weighted- average Exercise Price		Weighted- average Remaining Contractual Life (Years)		Aggregate Intrinsic Value (in thousands)
Vested		367,706	$	2.69		6.25	$	3,219
Expected to vest		532,244	$	10.32		9.49		606
Total		899,950	$	7.22		8.17	$	3,825

Summary of Expense Relating to Employee and Nonemployee Stock-Based Payment Awards

The Company’s results of operations include expense relating to employee and nonemployee stock-based payment awards as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Cost of testing	$	9	$	1	$	9	$	2
Research and development		21		2		22		4
Sales and marketing		8		1		9		2
General and administrative		99		15		145		30
	$	137	$	19	$	185	$	38

Weighted-Average Assumptions Used to Fair Value of Stock-Based Awards

The fair value of stock-based awards was estimated using the Black-Scholes option-pricing model using the following weighted-average assumptions:

	Three Months Ended June 30,						Six Months Ended June 30,
	2014			2013			2014			2013
Risk-free interest rate		1.74	%		1.02	%		1.70	%		1.02	%
Volatility		42.18	%		45.29	%		41.84	%		45.41	%
Expected term, in years		5.3			6.0			5.1			6.0
Expected dividend yield		0.0	%		0.0	%		0.0	%		0.0	%