X0206 3 2015-10-21 0 0001592288 Dimension Therapeutics, Inc. DMTX 0001653056 Wadsworth Samuel C. C/O DIMENSION THERAPEUTICS, INC. 840 MEMORIAL DRIVE, 4TH FLOOR CAMBRIDGE MA 02139 0 1 0 0 Chief Scientific Officer Common Stock 242247 D Common Stock 35788 D These shares were acquired pursuant to a restricted stock grant under the Company's 2013 Stock Plan. These shares vest over four (48) months beginning on October 30, 2013, at a rate of twenty-five percent (25%) after 12 months and in thirty-six (36) equal monthly installments thereafter. These shares were acquired pursuant to a restricted stock grant under the Company's 2013 Stock Plan. These shares vest over four (48) months beginning on November 1, 2013, at a rate of twenty-five percent (25%) after 12 months and in thirty-six (36) equal monthly installments thereafter. Exhibit 24.1: Limited Power of Attorney /s/ Mary Thistle, as Attorney-in-Fact for Samuel C. Wadsworth 2015-10-21