Related Party Transactions	3 Months Ended
Related Party Transactions	Mar. 31, 2013
Related Party Transactions
Related Party Transactions	10. Related Party Transactions The Company’s chief executive officer, Michelle Dipp, M.D., Ph.D., has not historically received any cash compensation for her service as chief executive officer because of her service as a general partner of one of the Company’s principal stockholders. Pursuant to the terms of an employment agreement that the Company entered into with Dr. Dipp, in December 2012 the Company granted Dr. Dipp an option to purchase 339,313 shares of its common stock and restricted stock units in the aggregate amount of 192,308 shares of its common stock. In addition, the Company may in the future determine to compensate Dr. Dipp with cash or other compensation.

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

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