Exhibit 12.1

Computation of Deficiency in the Coverage of Fixed Charges by Earnings Before Fixed Charges and Preferred Stock

Dividends

	Year ended December 31,
	2007			2008			2009			2010			2011
	(in thousands)
Fixed charges:
Interest expense	$	104		$	104		$	97		$	94		$	90
Estimate of interest expense within rental expense		129			129			153			204			220
Total fixed charges	$	233		$	233		$	250		$	298		$	310
Earnings before fixed charges:
Net loss before provision for income taxes	$	(27,168	)	$	(23,953	)	$	(25,159	)	$	(32,177	)	$	(2,318	)
Add fixed charges		233			233			250			298			310
Total earnings (loss) before fixed charges	$	(26,935	)	$	(23,720	)	$	(24,909	)	$	(31,879	)	$	(2,008	)
Deficiency of earnings to cover fixed charges:	$	(27,168	)	$	(23,953	)	$	(25,159	)	$	(32,177	)	$	(2,318	)
Earnings before fixed charges and preferred stock dividends:
Net loss before provision for income taxes	$	(27,168	)	$	(23,953	)	$	(25,159	)	$	(32,177	)	$	(2,318	)
Add fixed charges		233			233			250			298			310
Add preferred stock dividends		—			—			—			—			—
Total earnings (loss) before fixed charges and preferred stock dividends	$	(26,935	)	$	(23,720	)	$	(24,909	)	$	(31,879	)	$	(2,008	)
Deficiency of earnings to cover fixed charges and preferred stock dividends:	$	(27,168	)	$	(23,953	)	$	(25,159	)	$	(32,177	)	$	(2,318	)