Related party transactions	6 Months Ended
Related party transactions	Jun. 30, 2016
Related party transactions
Related party transactions	10. Related‑Party Transactions During the three and six months ended June 30, 2016 and June 30, 2015, the Company received consulting and management services from one of its investors. The total amount of consulting and management services provided by this investor was approximately $16,000 and $19,000 during the three and six months ended June 30, 2016, respectively. The total amount of services provided by this investor was approximately $45,000 and $115,000 during the three and six months ended June 30, 2015, respectively. As of June 30, 2016, the Company had a balance of $16,000 in accounts payable related to service fees charged by this investor. During the three and six months ended June 30, 2016, the Company recognized $3,720,000 and $8,550,000, respectively, of revenue associated with the Collaboration Agreement related to research and development services provided during this period. During the three and six months ended June 30, 2015, the Company recognized $4,884,000 and $7,460,000, respectively, of revenue associated with the Collaboration Agreement related to research and development services provided during the period. The Company also recognized $271,000 and $753,000 of expense during the three and six months ended June 30, 2016, respectively, related to in‑kind services provided by Genzyme associated with the Collaboration Agreement. The Company recognized $1,059,000 and $2,065,000 of expense during the three and six months ended June 30, 2015, respectively, related to in-kind services provided by Genzyme under the Collaboration Agreement.

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.