X0609 4 2026-06-04 0 0001818331 GeneDx Holdings Corp. WGS 0001534261 Casdin Capital, LLC false 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK NY 10019 1 0 1 0 0001534264 Casdin Eli false 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK NY 10019 1 0 1 0 0001534265 Casdin Partners Master Fund, L.P. false 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK NY 10019 1 0 1 0 0001534260 Casdin Partners GP, LLC false 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK NY 10019 1 0 1 0 0 Class A Common Stock, par value $0.0001 per share 2026-06-04 4 P 0 150000 56.4449 A 3657164 I See footnote Class A Common Stock, par value $0.0001 per share 2026-06-05 4 P 0 50000 52.8566 A 3707164 I See footnote Class A Common Stock, par value $0.0001 per share 20517 D Class A Common Stock, par value $0.0001 per share 19247 I See footnote Class A Common Stock, par value $0.0001 per share 333144 I See footnote The securities are owned directly by the Casdin Partners Master Fund, L.P. (the "Master Fund") and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to the Master Fund ("Casdin"), (ii) Casdin Partners GP, LLC, the general partner of the Master Fund (the "GP"), and (iii) Eli Casdin, the managing member of Casdin and the GP. The securities are owned directly by Eli Casdin. The securities are owned directly by the GP and may be deemed to be indirectly beneficially owned by Eli Casdin, the managing member of the GP. The securities are owned directly by CMLS Holdings LLC ("CMLS Holdings"). The Board of Managers of CMLS Holdings includes Eli Casdin, who, as a member of the Board of Managers of CMLS Holdings, shares voting and investment discretion with respect to the common stock held by CMLS Holdings. Each Reporting Person disclaims beneficial ownership in the securities reported on this Form 4 except to the extent of its pecuniary interest, if any, therein, and this report shall not be deemed to be an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose. Casdin Partners Master Fund, LP, By: Casdin Partners GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member 2026-06-08 Casdin Capital LLC, By: /s/ Eli Casdin Managing Member 2026-06-08 Casdin Partners GP LLC, By: /s/ Eli Casdin Managing Member, /s/ Eli Casdin, Eli Casdin 2026-06-08 /s/ Eli Casdin, Eli Casdin 2026-06-08