Intellia Therapeutics announced voluntary pauses to dosing and screening in two Phase 3 programs for nexiguran ziclumeran (nex‑z), and the FDA imposed clinical holds on the INDs after a treated patient developed severe liver enzyme elevations consistent with Hy’s law. The safety signal emerged in patients enrolled in MAGNITUDE and MAGNITUDE‑2, which evaluate an in vivo CRISPR therapy partnered with Regeneron for transthyretin amyloidosis with cardiomyopathy (ATTR‑CM). Company management disclosed the event and regulatory action on an analyst call and in regulatory filings. The hospitalized patient—stable at the time of disclosure—triggered broad pharmacovigilance reviews; over 450 patients had been dosed across trials. The FDA’s hold will require Intellia to provide additional safety analyses and potentially protocol amendments before dosing can resume. This pause highlights the risk profile of systemic, in vivo gene‑editing approaches and could affect timelines for other CRISPR in‑vivo developers and their investors. Sponsors will need to clarify monitoring, mitigation, and patient‑selection strategies to restore regulatory confidence.