X0306 4 2019-07-22 0 0001759425 Mirum Pharmaceuticals, Inc. MIRM 0001365617 Heron Patrick J C/O FRAZIER HEALTHCARE PARTNERS 70 WILLOW ROAD, SUITE 200 MENLO PARK CA 94025 1 0 1 0 Common Stock 2019-07-22 4 C 0 3116912 A 3116912 I By Frazier Life Sciences IX, L.P. Common Stock 2019-07-22 4 P 0 450000 15.00 A 3566912 I By Frazier Life Sciences IX, L.P. Series A Preferred Stock 2019-07-22 4 C 0 24935300 0.00 D Common Stock 3116912 0 I By Frazier Life Sciences IX, L.P. In connection with the Issuer's initial public offering, each share of the Issuer's Series A Preferred Stock automatically converted into 0.125 shares of the Issuer's Common Stock. The shares have no expiration date. The shares are held directly by Frazier Life Sciences IX, L.P. FHMLS IX, L.P. is the general partner of Frazier Life Sciences IX, L.P. FHMLS IX, L.L.C. is the general partner of FHMLS IX, L.P. The Reporting Person and James N. Topper are the managing members of FHMLS IX, L.L.C. and share voting and dispositive power over the shares held by Frazier Life Sciences IX, L.P. The Reporting Person disclaims beneficial ownership of the shares, except to the extent of his pecuniary interest therein. The shares were purchased in the Issuer's initial public offering. /s/ Jody Howe, Attorney-in-Fact 2019-07-24