Joint Filer Information

Names:	Deerfield Mgmt IV, L.P., Deerfield Mgmt HIF, L.P., Deerfield Management Company, L.P., Deerfield Private Design Fund IV, L.P. and Deerfield Healthcare Innovations Fund, L.P.
Address:	780 Third Avenue, 37th Floor New York, NY 10017
Designated Filer:	James E. Flynn
Issuer and Ticker Symbol:	Mirum Pharmaceuticals, Inc. [MIRM]
Date of Event Requiring Statement:	July 17, 2019

The undersigned, Deerfield Mgmt IV, L.P., Deerfield Mgmt HIF, L.P., Deerfield Management Company, L.P., Deerfield Private Design Fund IV, L.P. and Deerfield Healthcare Innovations Fund, L.P., are jointly filing the attached Initial Statement of Beneficial Ownership on Form 3 with James E. Flynn with respect to the beneficial ownership of securities of Mirum Pharmaceuticals, Inc.

Signatures:

DEERFIELD MGMT IV, L.P. By: J.E. Flynn Capital IV, LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact	DEERFIELD MGMT HIF, L.P. By: J.E. Flynn Capital HIF, LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact
DEERFIELD MANAGEMENT COMPANY, L.P. By: Flynn Management LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact	DEERFIELD HEALTHCARE INNOVATIONS FUND, L.P. By: Deerfield Mgmt HIF, L.P., General Partner By: J.E. Flynn Capital HIF, LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact
DEERFIELD PRIVATE DESIGN FUND IV, L.P. By: Deerfield Mgmt IV, L.P., General Partner By: J.E. Flynn Capital IV, LLC, General Partner By: /s/ Jonathan Isler Jonathan Isler, Attorney-In-Fact