Amended Statement of Changes in Beneficial Ownership (4/a)

FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^* Mostafa Adam S.	2. Issuer Name and Ticker or Trading Symbol X4 Pharmaceuticals, Inc [ XFOR ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __ X __ Officer (give title below) _____ Other (specify below) See Remarks
(Last) (First) (Middle) C/O X4 PHARMACEUTICALS, INC., 955 MASSACHUSETTS AVENUE, 4TH FLOOR	3. Date of Earliest Transaction (MM/DD/YYYY) 3/13/2019
(Street) CAMBRIDGE, MA (City) (State) (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY) 3/14/2019	6. Individual or Joint/Group Filing (Check Applicable Line) _ X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)

*Table II - Derivative Securities Beneficially Owned ( e.g.* , puts, calls, warrants, options, convertible securities)**
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)			11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option (right to buy)	$10.44	3/13/2019		A		62633		⁽¹⁾	10/3/2028	Common Stock	62633	⁽²⁾	62633	D

Explanation of Responses:
(1)	Twenty-five percent (25%) of the shares subject to the option shall vest on September 5, 2019, and one thirty-sixth (1/36th) of the remaining shares subject to the option shall vest each month thereafter, subject to the Reporting Person continuing to provide service through each such date. This amendment is being filed solely to correct the vesting schedule of the option included in the Form 4 filed on March 14, 2019.
(2)	Reflects the Reporting Person's stock option to acquire 659,067 shares of X4 common stock for $0.99 per share that was assumed by the Issuer in the merger of Artemis AC Corp., a wholly-owned subsidiary of the Issuer, with and into X4 Therapeutics, Inc. (formerly X4 Pharmaceuticals, Inc.) ("X4") on March 13, 2019 (the "Merger").

Remarks:
Chief Financial Officer and Treasurer

All share and per share amounts of the Issuer's common stock and stock options reported in this Form 4 reflect the 1-for-6 reverse stock split of the Issuer's common stock effected on March 13, 2019 after the completion of the Merger.

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
Mostafa Adam S. C/O X4 PHARMACEUTICALS, INC. 955 MASSACHUSETTS AVENUE, 4TH FLOOR CAMBRIDGE, MA			See Remarks

Signatures
/s/ Adam S. Mostafa		3/15/2019
^** 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 4(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).
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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