Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 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 * ROCHE HOLDINGS INC	2. Date of Event Requiring Statement (MM/DD/YYYY) 12/17/2019	3. Issuer Name and Ticker or Trading Symbol Spark Therapeutics, Inc. [ONCE]
(Last)        (First)        (Middle) 1 DNA WAY,, MS #24	4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                          ___X___ 10% Owner _____ Officer (give title below)        _____ Other (specify below)
(Street) SOUTH SAN FRANCISCO, CA 94080       (City)              (State)              (Zip)	5. If Amendment, Date Original Filed(MM/DD/YYYY)	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	29746673	D (1)(2)(3)(4)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		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

Explanation of Responses:
(1)	This statement is being filed jointly by Roche Holdings, Inc. ("Holdings") and Roche Holdings, Ltd ("Parent" and, together with Holdings, the "Reporting Persons"). Holdings is a subsidiary of Parent. Additionally, the Reporting Persons understand that certain shareholders of Parent are party to a shareholder pooling agreement with respect to a significant portion of (but not a majority of) the issued shares of Parent.
(2)	On February 22, 2019, Holdings and the Issuer entered into a Transaction Agreement (the "Transaction Agreement"), pursuant to which Holdings has consummated a tender offer (the "Tender Offer") to purchase all outstanding shares ("Shares") of common stock of the Issuer.
(3)	Holdings is the direct beneficial owner of these Shares. Parent is the indirect beneficial owner of these Shares.
(4)	Each Reporting Person disclaims beneficial ownership of the Shares reported in Table I except to the extent of its pecuniary interest therein, if any. Each Reporting Person also disclaims beneficial ownership of any Shares that may be or are beneficially owned by any other person. This Form 3 shall not be deemed an admission that any Reporting Person or other person is a beneficial owner of any Shares for any purpose, other than as reported in Table I above.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
ROCHE HOLDINGS INC 1 DNA WAY, MS #24 SOUTH SAN FRANCISCO, CA 94080		X
ROCHE HOLDING LTD ROCHE HOLDING, LTD. GRENZACHERSTRASSE 124 BASEL, V8 CH-4070		X

Signatures
/s/ Bruce Resnick on behalf of Roche Holdings, Inc.		12/17/2019
**Signature of Reporting Person		Date
/s/ Beat Kraehenmann on behalf of Roche Holding Ltd		12/17/2019
**Signature of Reporting Person		Date