X0508 4 2023-09-11 0 0001759425 Mirum Pharmaceuticals, Inc. MIRM 0001365617 Heron Patrick J C/O FRAZIER LIFE SCIENCES 70 WILLOW ROAD, SUITE 200 MENLO PARK CA 94025 1 0 0 0 0 Common Stock 2023-09-11 4 P 0 4687 30.3024 A 152678 I By Frazier Life Sciences X, L.P. Common Stock 2023-09-12 4 P 0 3750 30.6037 A 156428 I By Frazier Life Sciences X, L.P. Common Stock 3566912 I By Frazier Life Sciences IX, L.P. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $30.0968 to $30.4835, inclusive. The Reporting Person undertakes to provide to Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in footnotes (1) and (3) to this Form 4. The shares are held directly by Frazier Life Sciences X, L.P. FHMLS X, L.P. is the general partner of Frazier Life Sciences X, L.P. FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. The Reporting Person and James N. Topper are the managing members of FHMLS X, L.L.C. and share voting and dispositive power over the shares held by Frazier Life Sciences X, L.P. The Reporting Person disclaims beneficial ownership of the shares, except to the extent of his pecuniary interest therein. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $30.2781 to $30.7970, inclusive. 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. /s/ Steve R. Bailey, as Attorney-in-Fact 2023-09-13