SEC 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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1. Name and Address of Reporting Person*
Blackstone Holdings II L.P.	

(Last)	(First)	(Middle)	
C/O THE BLACKSTONE GROUP L.P.	
345 PARK AVENUE	

(Street) 
NEW YORK	NY	10154	

(City)	(State)	(Zip)	
	2. Date of Event Requiring Statement (Month/Day/Year)
01/04/2019 	3. Issuer Name and Ticker or Trading Symbol 
AVROBIO, Inc. [ AVRO ] 		
		4. Relationship of Reporting Person(s) to Issuer 
(Check all applicable) 
	Director	X	10% Owner	
	Officer (give title below)		Other (specify below)	
	
	5. If Amendment, Date of Original Filed (Month/Day/Year)				
			6. Individual or Joint/Group Filing (Check Applicable Line) 
	Form filed by One Reporting Person	
X	Form filed by More than One Reporting Person	
	
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	2,962,325	I	See Footnotes(1)(2)(3) 	
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: 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				
1. Name and Address of Reporting Person*
Blackstone Holdings II L.P.	

(Last)	(First)	(Middle)	
C/O THE BLACKSTONE GROUP L.P.	
345 PARK AVENUE	

(Street) 
NEW YORK	NY	10154	

(City)	(State)	(Zip)	
	
1. Name and Address of Reporting Person*
Blackstone Clarus III L.L.C.	

(Last)	(First)	(Middle)	
C/O THE BLACKSTONE GROUP L.P.	
345 PARK AVENUE	

(Street) 
NEW YORK	NY	10154	

(City)	(State)	(Zip)	
	
1. Name and Address of Reporting Person*
Blackstone Holdings I/II GP Inc	

(Last)	(First)	(Middle)	
C/O THE BLACKSTONE GROUP L.P.	
345 PARK AVENUE	

(Street) 
NEW YORK	NY	10154	

(City)	(State)	(Zip)	
	
1. Name and Address of Reporting Person*
Blackstone Group L.P.	

(Last)	(First)	(Middle)	
345 PARK AVENUE	

(Street) 
NEW YORK	NY	10154	

(City)	(State)	(Zip)	
	
1. Name and Address of Reporting Person*
Blackstone Group Management L.L.C.	

(Last)	(First)	(Middle)	
C/O THE BLACKSTONE GROUP L.P.	
345 PARK AVENUE	

(Street) 
NEW YORK	NY	10154	

(City)	(State)	(Zip)	
	
1. Name and Address of Reporting Person*
SCHWARZMAN STEPHEN A	

(Last)	(First)	(Middle)	
C/O THE BLACKSTONE GROUP L.P.	
345 PARK AVENUE	

(Street) 
NEW YORK	NY	10154	

(City)	(State)	(Zip)	
	
Explanation of Responses:	
1. These securities are held directly by Clarus Lifesciences III, L.P. ("Clarus III"). Clarus Ventures III GP, L.P. ("Clarus III GP") is the sole general partner of Clarus III. Blackstone Clarus III L.L.C. is the sole general partner of Clarus GP. The sole member of Blackstone Clarus III L.L.C. is Blackstone Holdings II L.P. The sole general partner of Blackstone Holdings II L.P. is Blackstone Holdings I/II GP Inc. The controlling shareholder of Blackstone Holdings I/II GP Inc. is The Blackstone Group L.P. The sole general partner of The Blackstone Group L.P. is Blackstone Group Management L.L.C. Blackstone Group Management L.L.C. is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.	
2. Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.	
3. Each of such Reporting Persons may be deemed to beneficially own the shares beneficially owned by Clarus III, but each disclaims beneficial ownership of such shares, except to the extent of such Reporting Person's pecuniary interest therein. The filing of this statement shall not be deemed to be an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the Reporting Persons are the beneficial owners of any securities reported herein.	
Remarks:	
This Form 3 is being filed in connection with the acquisition by The Blackstone Group L.P. and certain of its affiliates ("Blackstone") of Clarus Ventures, LLC and certain of its affiliates (collectively, "Clarus"). On January 4, 2019, Blackstone integrated the Clarus business into Blackstone (the "Clarus Integration"). As a result of such integration, Blackstone may be deemed to have become the beneficial owner of the securities beneficially owned by Clarus, including the securities of the Issuer.	
	BLACKSTONE CLARUS III L.L.C., By: Blackstone Holdings II L.P., its managing member, By: Blackstone Holdings I/II GP Inc., its general partner, By: /s/ John G. Finley, Name: John G. Finley, Title: Chief Legal Officer	01/10/2019	
	BLACKSTONE HOLDINGS II L.P., By: Blackstone Holdings I/II GP Inc., its general partner, By: /s/ John G. Finley, Name: John G. Finley, Title: Chief Legal Officer	01/10/2019	
	BLACKSTONE HOLDINGS I/II GP INC., By: /s/ John G. Finley, Name: John G. Finley, Title: Chief Legal Officer	01/10/2019	
	THE BLACKSTONE GROUP L.P., By: Blackstone Group Management L.L.C., its general partner, By: /s/ John G. Finley, Name: John G. Finley, Title: Chief Legal Officer	01/10/2019	
	BLACKSTONE GROUP MANAGEMENT L.L.C., By: /s/ John G. Finley, Name: John G. Finley, Title: Chief Legal Officer	01/10/2019	
	/s/ Stephen A. Schwarzman	01/10/2019	
	** Signature of Reporting Person	Date	
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.	
* 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).	
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