A joint UCL–UCLA team reported multi‑year follow‑up data in The New England Journal of Medicine showing a gene therapy for ADA‑SCID achieved approximately 95% success restoring immune function with no serious safety signals in treated children. Investigators described durable immune reconstitution that eliminated reliance on enzyme‑replacement therapies and immunoglobulin infusions for most patients. The program, developed over decades by Claire Booth and Donald Kohn among others, used ex vivo gene correction and autologous hematopoietic cell reinfusion. The NEJM report and accompanying interviews detail long timelines, manufacturing and access challenges, and implications for single‑patient or bespoke gene therapies becoming broader, possibly curative options for inherited immune disorders.