EXHIBIT A

AGREEMENT

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, the undersigned hereby agree that only one statement containing the information required by Schedule 13D need be filed with respect to the ownership by each of the undersigned of Common Stock of Mirum Pharmaceuticals, Inc.

Date: September 5, 2023	FRAZIER LIFE SCIENCES IX, L.P.
	By FHMLS IX, L.P., its general partner
	By FHMLS IX, L.L.C., its general partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FHMLS IX, L.P.
	By FHMLS IX, L.L.C., its general partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FHMLS IX, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FRAZIER LIFE SCIENCES X, L.P.
	By FHMLS X, L.P., its general partner
	By FHMLS X, L.L.C., its general partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FHMLS X, L.P.
	By FHMLS X, L.L.C., its general partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer

Date: September 5, 2023	FHMLS X, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FRAZIER LIFE SCIENCES PUBLIC FUND, L.P.
	By:	FHMLSP, L.P., its General Partner
	By:	FHMLSP, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FHMLSP, L.P.
	By:	FHMLSP, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FHMLSP, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FRAZIER LIFE SCIENCES PUBLIC OVERAGE FUND, L.P.
	By:	FHMLSP Overage, L.P., its General Partner
	By:	FHMLSP Overage, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FHMLSP OVERAGE, L.P.
	By FHMLSP Overage, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer

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Date: September 5, 2023	FHMLSP OVERAGE, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FRAZIER LIFE SCIENCES XI, L.P.
	By FHMLS XI, L.P., its general partner
	By FHMLS XI, L.L.C., its general partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FHMLS XI, L.P.
	By FHMLS XI, L.L.C., its general partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	FHMLS XI, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: September 5, 2023	By:	*
		James N. Topper
Date: September 5, 2023	By:	*
		Patrick J. Heron
Date: September 5, 2023	By:	**
		Albert Cha
Date: September 5, 2023	By:	**
		James Brush
Date: September 5, 2023	By:	***
		Daniel Estes

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Date: September 5, 2023	By:	/s/ Steve R. Bailey
		Steve R. Bailey, as Attorney-in-Fact

* This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on July 31, 2017.

** This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on August 16, 2021.

*** This Agreement was executed by Steve R. Bailey on behalf of the individual listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on April 18, 2022.

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