X0206 3 2022-12-02 0 0001707502 Solid Biosciences Inc. SLDB 0001703031 Bain Capital Life Sciences Investors, LLC 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001728056 BCLS SB Investco, LP 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001703030 Bain Capital Life Sciences Partners, LP 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001773187 Bain Capital Life Sciences Fund II, L.P. 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001796155 Bain Capital Life Sciences Investors II, LLC 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001818893 BCLS II Investco, LP 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001819101 BCLS II Investo (GP), LLC 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 0001702921 BCIP Life Sciences Associates, LP 200 CLARENDON STREET BOSTON MA 02116 0 0 1 0 Common Stock 3130423 I See footnotes Represents 2,301,955 shares of the Issuer's Common Stock held by BCLS II Investco, LP ("BCLS II Investco"), 528,661 shares of the Issuer's Common Stock held by BCLS SB Investco, LP ("BCLS SB"), 267,257 shares of the Issuer's Common Stock held by Bain Capital Life Sciences Fund II, L.P. ("BCLS Fund II"), and 32,550 shares of the Issuer's Common Stock held by BCIP Life Sciences Associates, LP ("BCIPLS" and, together with BCLS II Investco, BCLS SB and BCLS Fund II, the "Bain Capital Life Sciences Entities"). Bain Capital Life Sciences Investors II, LLC ("BCLSI II") is the general partner of BCLS Fund II. As a result, BCLSI II may be deemed to share voting and dispositive power with respect to the securities held by BCLS Fund II. BCLSI II disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein. BCLS II Investco (GP), LLC ("BCLS II Investco GP"), whose manager is BCLS Fund II, is the general partner of BCLS II Investco. As a result, each of BCLSI II, BCLS Fund II and BCLS II Investco GP may be deemed to share voting and dispositive power with respect to the securities held by BCLS II Investco. Each of BCLSI II, BCLS Fund II and BCLS II Investco GP disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein. Bain Capital Life Sciences Partners, LP ("BCLSP") is the general partner of BCLS SB. As a result, BCLSP may be deemed to share voting and dispositive power with respect to the securities held by BCLS SB. BCLSP disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein. Boylston Coinvestors, LLC is the general partner of BCIPLS. Bain Capital Life Sciences Investors, LLC ("BCLSI") (i) is the manager of BCLSI II, (ii) is the general partner of BCLSP and (iii) governs the investment strategy and decision-making process with respect to investments held by BCIPLS. As a result, BCLSI may be deemed to share voting and dispositive power with respect to the securities held by the Bain Capital Life Sciences Entities. BCLSI disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein. See signatures included in Exhibit 99.1 2022-12-05