Initial Statement of Beneficial Ownership (Form 3)

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * Atlas Venture Opportunity Fund Ill, L.P. 2. Date of Event Requiring Statement (Month/Day/Year) 05/26/2026 3. Issuer Name and Ticker or Trading Symbol Q32 Bio Inc. [QTTB] (Last) (First) (Middle) ATLAS VENTURE, 300 TECHNOLOGY SQUARE, 8TH FLOOR 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner _____ Officer (give title below) __X__ Other (specify below) See Remarks 5. If Amendment, Date Original Filed (Month/Day/Year) (Street) CAMBRIDGE, MA 02139 6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Beneficially Owned

1.Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5) Common Stock 625,000 D(1)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Atlas Venture Opportunity Fund Ill, L.P. ATLAS VENTURE 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE, MA 02139				See Remarks
Atlas Venture Associates Opportunity III, L.P. 300 TECHNOLOGY SQ., 8TH FLOOR CAMBRIDGE, MA 02139				See Remarks
Atlas Venture Associates Opportunity III, LLC 300 TECHNOLOGY SQ., 8TH FLOOR CAMBRIDGE, MA 02139				See Remarks

Signatures

Atlas Venture Opportunity Fund III, L.P., By: Atlas Venture Associates Opportunity III, L.P., its general partner, By: Atlas Venture Associates Opportunity III, LLC, its general partner, By: /s/ Ommer Chohan, Chief Financial Officer		06/08/2026
**Signature of Reporting Person		Date
Atlas Venture Associates Opportunity III, L.P., By: Atlas Venture Associates Opportunity III, LLC, its general partner, By: /s/ Ommer Chohan, Chief Financial Officer		06/08/2026
**Signature of Reporting Person		Date
Atlas Venture Associates Opportunity III, LLC, By: /s/ Ommer Chohan, Chief Financial Officer		06/08/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The shares are owned directly by Atlas Venture Opportunity Fund III, L.P. ("AVOF III"). Atlas Venture Associates Opportunity III, L.P. ("AVAO III LP") is the general partner of AVOF III. Atlas Venture Associates Opportunity III, LLC ("AVAO III LLC") is the general partner of AVAO III LP. Each of AVAO III LP and AVAO III LLC disclaims beneficial ownership of the securities held by AVOF III, except to the extent of its pecuniary interest therein, if any.
Remarks: The Reporting Persons are under common control with other entities affiliated with Atlas Venture who, together with the Reporting Persons, collectively beneficially own in the aggregate greater than 10% of the outstanding common stock of the Issuer. The Reporting Persons may be deemed to be members of a "group" with such other entities for purposes of Section 13 of the Exchange Act. However, the Reporting Persons disclaim such group membership, and this Form 3 shall not be deemed an admission that the Reporting Persons are members of a group for purposes of Section 13 of the Exchange Act or for any other purposes.

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