X0306 4 2020-07-28 1 0001693011 Inozyme Pharma, Inc. INZY 0001595725 Rock Springs Capital Management LP 650 SOUTH EXETER ST. SUITE 1070 BALTIMORE MD 21202 0 0 1 0 0001735393 Rock Springs Capital Master Fund LP C/O WALKERS CORPORATE LIMITED, CAYMAN CO CENTER, 27 HOSPITAL ROAD GEORAGE TOWN E9 KY-1-9008 CAYMAN ISLANDS 0 0 1 0 0001735397 Rock Springs Capital LLC 650 SOUTH EXETER ST. SUITE 1070 BALTIMORE MD 21202 0 0 1 0 Common Stock 2020-07-28 4 C 0 467884 A 467884 I See footnote Common Stock 2020-07-28 4 P 0 576000 16.00 A 1043884 I See footnote Common Stock 2020-07-28 4 P 0 24000 16.00 A 1067884 I See footnote Series A-2 Convertible Preferred Stock 2020-07-28 4 C 0 3496504 0.00 D Common Stock 467884 0 I See footnote On July 28, 2020, the Series A-2 Convertible Preferred Stock automatically converted into Common Stock on a 7.4730-for-1 basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A-2 Convertible Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date. The securities reported herein are held of record by Rock Springs Capital Master Fund LP ("Master Fund"). Rock Springs Capital LLC ("RSC") is the general partner of Rock Springs Capital Management LP ("RSCM") which is the investment manager to Master Fund. RSC and RSCM may therefore be deemed to have or share beneficial ownership of the Common Stock held directly by Master Fund. The securities reported herein are held of record by Four Pines Master Fund LP. RSC is the general partner of RSCM which is the investment manager to Four Pines Master Fund LP. RSC and RSCM may therefore be deemed to have or share beneficial ownership of the Common Stock held directly by Four Pines Master Fund LP. Rock Springs Capital Management LP, By: /s/ Stephen Basso, Attorney-in-Fact 2020-07-28 Rock Springs Capital Master Fund LP, By: /s/ Stephen Basso, Attorney-in-Fact 2020-07-28 Rock Springs Capital LLC, By: /s/ Stephen Basso, Attorney-in-Fact 2020-07-28