A collaborative UCL and UCLA gene therapy program reported durable immune reconstitution in children with ADA‑SCID, achieving reported success rates near 95% with no long‑term safety signals in multi‑year follow‑up. The peer‑reviewed report in The New England Journal of Medicine documents sustained clinical benefit and normalization of immune function after a one‑time ex vivo gene‑corrective approach. Investigators noted the therapy’s potential to replace lifelong enzyme replacement and transplant strategies for ADA‑SCID, while emphasizing the need for expanded access and manufacturing scale up to reach more patients.