Common Stock, $0.001 par value per share

Solid Biosciences Inc.

500 Rutherford Avenue, Charlestown, MA, 02129

The information set forth in rows 11 and 13 of the cover pages to this Schedule 13D is incorporated by reference. The percentages set forth in row 13 are based on a total of 107,365,171 shares of Common Stock, consisting of (i) 107,225,238 shares of Common Stock outstanding as of August 4, 2026, as disclosed by the Issuer in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on August 6, 2026, and (ii) 139,933 shares of Common Stock issuable upon exercise of vested stock options held by Adam Stone ("Mr. Stone"), the Chief Investment Officer of Perceptive Advisors LLC ("Perceptive Advisors"), described below.

The information set forth in rows 7 through 10 of the cover pages to this Schedule 13D is incorporated by reference. Neither Perceptive Advisors nor Joseph Edelman ("Mr. Edelman") directly holds any Common Stock or pre-funded warrants. Perceptive Life Sciences Master Fund, Ltd. (the "Master Fund") directly holds 11,833,539 shares of Common Stock and 8,912,655 pre-funded warrants (the "Pre-Funded Warrants") immediately exercisable for shares of Common Stock at an exercise price of $0.001 per share, subject to the Beneficial Ownership Limitation (as defined below). The terms of the Pre-Funded Warrants provide that the Pre-Funded Warrants may not be exercised if, after such exercise, the Reporting Persons would beneficially own, as determined in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended, more than 9.99% of the shares of Common Stock then issued and outstanding after giving effect to such exercise (the "Beneficial Ownership Limitation"). As of the date hereof, the Beneficial Ownership Limitation does not permit the Reporting Persons to exercise any portion of the Pre-Funded Warrants. Perceptive Xontogeny Venture Fund, LP (the "Venture Fund") directly holds 73,107 shares of Common Stock. Perceptive Advisors serves as the investment manager to the Master Fund and the Venture Fund. Mr. Edelman is the managing member of Perceptive Advisors. Adam Stone, the Chief Investment Officer of Perceptive Advisors, holds stock options for a total of 217,433 shares of Common Stock, of which 139,933 are currently exercisable, or exercisable within 60 days. The Master Fund has the right to receive the director compensation provided in respect of Mr. Stone's board service through a partial management fee offset.