BBIO

Item 4 of the Schedule 13D is hereby amended and supplemented as follows: Sale of Common Stock On August 13, 2026, KKR Genetic Disorder L.P., as a selling stockholder, and the Issuer entered into an underwriting agreement (the ''Underwriting Agreement'') with William Blair & Company, L.L.C., Goldman Sachs & Co. LLC and KKR Capital Markets LLC (the ''Representatives''), as the representatives of the several underwriters listed on Schedule I thereto (the ''Underwriters''), relating to an offering of 5,000,000 shares of Common Stock by KKR Genetic Disorder L.P. (the ''Offering''), and purchase by the Underwriters of the shares of Common Stock, at a net price to KKR Genetic Disorder L.P. of $77.415 per share. The Offering closed on August 17, 2026. The Offering was made pursuant to the Issuer's effective shelf registration statement on Form S-3ASR (File No. 333-297701), including the prospectus, dated July 24, 2026, as supplemented by a prospectus supplement, dated August 13, 2026, filed on August 14, 2026. Pursuant to the Underwriting Agreement, KKR Genetic Disorder L.P. entered into a lock-up agreement (the ''Lock-Up Agreement'') with the Underwriters pursuant to which it has agreed with the Underwriters, subject to certain exceptions, not to dispose of or hedge any of their Common Stock or securities convertible into or exchangeable for shares of Common Stock, during the period from August 13, 2026 continuing through the date 30 days after the date of the final prospectus supplement used in connection with the Offering, except with the prior written consent of the Representatives. The foregoing descriptions of the Underwriting Agreement and the Lock-Up Agreement do not purport to be complete and are subject to, and qualified in their entirety by, the full text of such agreements, which are filed as Exhibits J and K respectively hereto, and are incorporated herein by reference.

Item 4 of the Schedule 13D is hereby amended and supplemented as follows: Sale of Common Stock On August 13, 2026, KKR Genetic Disorder L.P., as a selling stockholder, and the Issuer entered into an underwriting agreement (the ''Underwriting Agreement'') with William Blair & Company, L.L.C., Goldman Sachs & Co. LLC and KKR Capital Markets LLC (the ''Representatives''), as the representatives of the several underwriters listed on Schedule I thereto (the ''Underwriters''), relating to an offering of 5,000,000 shares of Common Stock by KKR Genetic Disorder L.P. (the ''Offering''), and purchase by the Underwriters of the shares of Common Stock, at a net price to KKR Genetic Disorder L.P. of $77.415 per share. The Offering closed on August 17, 2026. The Offering was made pursuant to the Issuer's effective shelf registration statement on Form S-3ASR (File No. 333-297701), including the prospectus, dated July 24, 2026, as supplemented by a prospectus supplement, dated August 13, 2026, filed on August 14, 2026. Pursuant to the Underwriting Agreement, KKR Genetic Disorder L.P. entered into a lock-up agreement (the ''Lock-Up Agreement'') with the Underwriters pursuant to which it has agreed with the Underwriters, subject to certain exceptions, not to dispose of or hedge any of their Common Stock or securities convertible into or exchangeable for shares of Common Stock, during the period from August 13, 2026 continuing through the date 30 days after the date of the final prospectus supplement used in connection with the Offering, except with the prior written consent of the Representatives. The foregoing descriptions of the Underwriting Agreement and the Lock-Up Agreement do not purport to be complete and are subject to, and qualified in their entirety by, the full text of such agreements, which are filed as Exhibits J and K respectively hereto, and are incorporated herein by reference.

Item 4 of the Schedule 13D is hereby amended and supplemented as follows: Sale of Common Stock On August 13, 2026, KKR Genetic Disorder L.P., as a selling stockholder, and the Issuer entered into an underwriting agreement (the ''Underwriting Agreement'') with William Blair & Company, L.L.C., Goldman Sachs & Co. LLC and KKR Capital Markets LLC (the ''Representatives''), as the representatives of the several underwriters listed on Schedule I thereto (the ''Underwriters''), relating to an offering of 5,000,000 shares of Common Stock by KKR Genetic Disorder L.P. (the ''Offering''), and purchase by the Underwriters of the shares of Common Stock, at a net price to KKR Genetic Disorder L.P. of $77.415 per share. The Offering closed on August 17, 2026. The Offering was made pursuant to the Issuer's effective shelf registration statement on Form S-3ASR (File No. 333-297701), including the prospectus, dated July 24, 2026, as supplemented by a prospectus supplement, dated August 13, 2026, filed on August 14, 2026. Pursuant to the Underwriting Agreement, KKR Genetic Disorder L.P. entered into a lock-up agreement (the ''Lock-Up Agreement'') with the Underwriters pursuant to which it has agreed with the Underwriters, subject to certain exceptions, not to dispose of or hedge any of their Common Stock or securities convertible into or exchangeable for shares of Common Stock, during the period from August 13, 2026 continuing through the date 30 days after the date of the final prospectus supplement used in connection with the Offering, except with the prior written consent of the Representatives. The foregoing descriptions of the Underwriting Agreement and the Lock-Up Agreement do not purport to be complete and are subject to, and qualified in their entirety by, the full text of such agreements, which are filed as Exhibits J and K respectively hereto, and are incorporated herein by reference.

Item 4 of the Schedule 13D is hereby amended and supplemented as follows: Sale of Common Stock On August 13, 2026, KKR Genetic Disorder L.P., as a selling stockholder, and the Issuer entered into an underwriting agreement (the ''Underwriting Agreement'') with William Blair & Company, L.L.C., Goldman Sachs & Co. LLC and KKR Capital Markets LLC (the ''Representatives''), as the representatives of the several underwriters listed on Schedule I thereto (the ''Underwriters''), relating to an offering of 5,000,000 shares of Common Stock by KKR Genetic Disorder L.P. (the ''Offering''), and purchase by the Underwriters of the shares of Common Stock, at a net price to KKR Genetic Disorder L.P. of $77.415 per share. The Offering closed on August 17, 2026. The Offering was made pursuant to the Issuer's effective shelf registration statement on Form S-3ASR (File No. 333-297701), including the prospectus, dated July 24, 2026, as supplemented by a prospectus supplement, dated August 13, 2026, filed on August 14, 2026. Pursuant to the Underwriting Agreement, KKR Genetic Disorder L.P. entered into a lock-up agreement (the ''Lock-Up Agreement'') with the Underwriters pursuant to which it has agreed with the Underwriters, subject to certain exceptions, not to dispose of or hedge any of their Common Stock or securities convertible into or exchangeable for shares of Common Stock, during the period from August 13, 2026 continuing through the date 30 days after the date of the final prospectus supplement used in connection with the Offering, except with the prior written consent of the Representatives. The foregoing descriptions of the Underwriting Agreement and the Lock-Up Agreement do not purport to be complete and are subject to, and qualified in their entirety by, the full text of such agreements, which are filed as Exhibits J and K respectively hereto, and are incorporated herein by reference.

Item 4 of the Schedule 13D is hereby amended and supplemented as follows: Sale of Common Stock On August 13, 2026, KKR Genetic Disorder L.P., as a selling stockholder, and the Issuer entered into an underwriting agreement (the ''Underwriting Agreement'') with William Blair & Company, L.L.C., Goldman Sachs & Co. LLC and KKR Capital Markets LLC (the ''Representatives''), as the representatives of the several underwriters listed on Schedule I thereto (the ''Underwriters''), relating to an offering of 5,000,000 shares of Common Stock by KKR Genetic Disorder L.P. (the ''Offering''), and purchase by the Underwriters of the shares of Common Stock, at a net price to KKR Genetic Disorder L.P. of $77.415 per share. The Offering closed on August 17, 2026. The Offering was made pursuant to the Issuer's effective shelf registration statement on Form S-3ASR (File No. 333-297701), including the prospectus, dated July 24, 2026, as supplemented by a prospectus supplement, dated August 13, 2026, filed on August 14, 2026. Pursuant to the Underwriting Agreement, KKR Genetic Disorder L.P. entered into a lock-up agreement (the ''Lock-Up Agreement'') with the Underwriters pursuant to which it has agreed with the Underwriters, subject to certain exceptions, not to dispose of or hedge any of their Common Stock or securities convertible into or exchangeable for shares of Common Stock, during the period from August 13, 2026 continuing through the date 30 days after the date of the final prospectus supplement used in connection with the Offering, except with the prior written consent of the Representatives. The foregoing descriptions of the Underwriting Agreement and the Lock-Up Agreement do not purport to be complete and are subject to, and qualified in their entirety by, the full text of such agreements, which are filed as Exhibits J and K respectively hereto, and are incorporated herein by reference.

Item 4 of the Schedule 13D is hereby amended and supplemented as follows: Sale of Common Stock On August 13, 2026, KKR Genetic Disorder L.P., as a selling stockholder, and the Issuer entered into an underwriting agreement (the ''Underwriting Agreement'') with William Blair & Company, L.L.C., Goldman Sachs & Co. LLC and KKR Capital Markets LLC (the ''Representatives''), as the representatives of the several underwriters listed on Schedule I thereto (the ''Underwriters''), relating to an offering of 5,000,000 shares of Common Stock by KKR Genetic Disorder L.P. (the ''Offering''), and purchase by the Underwriters of the shares of Common Stock, at a net price to KKR Genetic Disorder L.P. of $77.415 per share. The Offering closed on August 17, 2026. The Offering was made pursuant to the Issuer's effective shelf registration statement on Form S-3ASR (File No. 333-297701), including the prospectus, dated July 24, 2026, as supplemented by a prospectus supplement, dated August 13, 2026, filed on August 14, 2026. Pursuant to the Underwriting Agreement, KKR Genetic Disorder L.P. entered into a lock-up agreement (the ''Lock-Up Agreement'') with the Underwriters pursuant to which it has agreed with the Underwriters, subject to certain exceptions, not to dispose of or hedge any of their Common Stock or securities convertible into or exchangeable for shares of Common Stock, during the period from August 13, 2026 continuing through the date 30 days after the date of the final prospectus supplement used in connection with the Offering, except with the prior written consent of the Representatives. The foregoing descriptions of the Underwriting Agreement and the Lock-Up Agreement do not purport to be complete and are subject to, and qualified in their entirety by, the full text of such agreements, which are filed as Exhibits J and K respectively hereto, and are incorporated herein by reference.

Item 4 of the Schedule 13D is hereby amended and supplemented as follows: Sale of Common Stock On August 13, 2026, KKR Genetic Disorder L.P., as a selling stockholder, and the Issuer entered into an underwriting agreement (the ''Underwriting Agreement'') with William Blair & Company, L.L.C., Goldman Sachs & Co. LLC and KKR Capital Markets LLC (the ''Representatives''), as the representatives of the several underwriters listed on Schedule I thereto (the ''Underwriters''), relating to an offering of 5,000,000 shares of Common Stock by KKR Genetic Disorder L.P. (the ''Offering''), and purchase by the Underwriters of the shares of Common Stock, at a net price to KKR Genetic Disorder L.P. of $77.415 per share. The Offering closed on August 17, 2026. The Offering was made pursuant to the Issuer's effective shelf registration statement on Form S-3ASR (File No. 333-297701), including the prospectus, dated July 24, 2026, as supplemented by a prospectus supplement, dated August 13, 2026, filed on August 14, 2026. Pursuant to the Underwriting Agreement, KKR Genetic Disorder L.P. entered into a lock-up agreement (the ''Lock-Up Agreement'') with the Underwriters pursuant to which it has agreed with the Underwriters, subject to certain exceptions, not to dispose of or hedge any of their Common Stock or securities convertible into or exchangeable for shares of Common Stock, during the period from August 13, 2026 continuing through the date 30 days after the date of the final prospectus supplement used in connection with the Offering, except with the prior written consent of the Representatives. The foregoing descriptions of the Underwriting Agreement and the Lock-Up Agreement do not purport to be complete and are subject to, and qualified in their entirety by, the full text of such agreements, which are filed as Exhibits J and K respectively hereto, and are incorporated herein by reference.

Item 4 of the Schedule 13D is hereby amended and supplemented as follows: Sale of Common Stock On August 13, 2026, KKR Genetic Disorder L.P., as a selling stockholder, and the Issuer entered into an underwriting agreement (the ''Underwriting Agreement'') with William Blair & Company, L.L.C., Goldman Sachs & Co. LLC and KKR Capital Markets LLC (the ''Representatives''), as the representatives of the several underwriters listed on Schedule I thereto (the ''Underwriters''), relating to an offering of 5,000,000 shares of Common Stock by KKR Genetic Disorder L.P. (the ''Offering''), and purchase by the Underwriters of the shares of Common Stock, at a net price to KKR Genetic Disorder L.P. of $77.415 per share. The Offering closed on August 17, 2026. The Offering was made pursuant to the Issuer's effective shelf registration statement on Form S-3ASR (File No. 333-297701), including the prospectus, dated July 24, 2026, as supplemented by a prospectus supplement, dated August 13, 2026, filed on August 14, 2026. Pursuant to the Underwriting Agreement, KKR Genetic Disorder L.P. entered into a lock-up agreement (the ''Lock-Up Agreement'') with the Underwriters pursuant to which it has agreed with the Underwriters, subject to certain exceptions, not to dispose of or hedge any of their Common Stock or securities convertible into or exchangeable for shares of Common Stock, during the period from August 13, 2026 continuing through the date 30 days after the date of the final prospectus supplement used in connection with the Offering, except with the prior written consent of the Representatives. The foregoing descriptions of the Underwriting Agreement and the Lock-Up Agreement do not purport to be complete and are subject to, and qualified in their entirety by, the full text of such agreements, which are filed as Exhibits J and K respectively hereto, and are incorporated herein by reference.

Item 4 of the Schedule 13D is hereby amended and supplemented as follows: Sale of Common Stock On August 13, 2026, KKR Genetic Disorder L.P., as a selling stockholder, and the Issuer entered into an underwriting agreement (the ''Underwriting Agreement'') with William Blair & Company, L.L.C., Goldman Sachs & Co. LLC and KKR Capital Markets LLC (the ''Representatives''), as the representatives of the several underwriters listed on Schedule I thereto (the ''Underwriters''), relating to an offering of 5,000,000 shares of Common Stock by KKR Genetic Disorder L.P. (the ''Offering''), and purchase by the Underwriters of the shares of Common Stock, at a net price to KKR Genetic Disorder L.P. of $77.415 per share. The Offering closed on August 17, 2026. The Offering was made pursuant to the Issuer's effective shelf registration statement on Form S-3ASR (File No. 333-297701), including the prospectus, dated July 24, 2026, as supplemented by a prospectus supplement, dated August 13, 2026, filed on August 14, 2026. Pursuant to the Underwriting Agreement, KKR Genetic Disorder L.P. entered into a lock-up agreement (the ''Lock-Up Agreement'') with the Underwriters pursuant to which it has agreed with the Underwriters, subject to certain exceptions, not to dispose of or hedge any of their Common Stock or securities convertible into or exchangeable for shares of Common Stock, during the period from August 13, 2026 continuing through the date 30 days after the date of the final prospectus supplement used in connection with the Offering, except with the prior written consent of the Representatives. The foregoing descriptions of the Underwriting Agreement and the Lock-Up Agreement do not purport to be complete and are subject to, and qualified in their entirety by, the full text of such agreements, which are filed as Exhibits J and K respectively hereto, and are incorporated herein by reference.