On May 15, 2025, a research team from the Children's Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania published a landmark study in the New England Journal of Medicine(NEJM): the first successful application of a bespoke gene-editing therapy, developed for a single patient, to treat an infant with a rare and fatal genetic disorder—carbamoyl phosphate synthetase 1 (CPS1) deficiency.