Related party transactions	12 Months Ended
Related party transactions	Dec. 31, 2015
Related party transactions
Related party transactions	13. Related‑Party Transactions Since inception, the Company received consulting and management services from one of its investors. In January 2014, the Company issued 470,589 shares of common stock as partial compensation for these services. The fair value of the shares was approximately $238,000. The total amount of consulting and management services provided by this investor was approximately $122,000, $1,280,000, and $2,379,000 during the years ended December 31, 2015, 2014, and the period ended December 31, 2013, respectively. As of December 31, 2015, the Company included approximately $7,000 in accounts payable related to service fees charged by this investor. During the year ended December 31, 2015 the Company recognized $17,334,000 of revenue associated with its collaboration with Genzyme related to research and development services provided during this period. The company also recognized $2,316,000 of expense during the year ended December 31, 2015 related to in‑kind services provided by Genzyme associated with the collaboration arrangement.

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.