X0609 4 2026-10-06 0001661998 Q32 Bio Inc. QTTB 0002016144 Violette Shelia M. false Q32 BIO INC. 830 WINTER STREET WALTHAM MA 02451 false true false false Chief Scientific Officer false Common Stock 2026-10-06 4 S false 917 8.3197 D 126854 D Common Stock 36277 I By Violette Holdings LLC Represents shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of performance-based restricted stock units. These sales were automatic and not in the discretion of the Reporting Person. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $8.07 to $8.32. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, on request, full information regarding the number of shares sold at each separate price within the range set forth above. Shares held by Violette Holdings LLC ("Violette Holdings"). The Reporting Person is a manager of Violette Holdings and disclaims beneficial ownership of these shares except to the extent of her pecuniary interest therein, if any, and this report shall not be deemed an admission that she is the beneficial owner of such shares for purposes of Section 16 of the Exchange Act or for any other purpose. /s/ Eric Bell, Attorney-in-Fact 2026-10-14