Penn Scientists Use Custom CRISPR “base-editing” saves an infant with CPS1 deficiency
PENNSYLVANIA, PA., May 15, 2025 - US physicians at Children’s Hospital of Philadelphia and the University of Pennsylvania have used a bespoke CRISPR-based treatment to correct the DNA of an infant with carbamoyl-phosphate synthetase 1 (CPS1) deficiency, a lethal disorder that prevents the liver from detoxifying ammonia. Nicknamed KJ, the boy was diagnosed soon after birth and spent his first months in hospital on a strict low-protein diet. Within six months the team designed, manufactured and safety-tested a personalised adenine base-editing therapy packaged in fatty nanoparticles that home to liver cells. KJ received one infusion in February 2025 and two follow-up doses in March and April; doctors report he is “thriving”, tolerating more dietary protein and requiring fewer ammonia-removal drugs, though he will need lifelong monitoring. The case, detailed in the New England Journal of Medicine and presented at the American Society of Gene and Cell Therapy meeting, marks the first time DNA has been rewritten inside a living infant, and researchers say it foreshadows a new era of rapid, one-patient-at-a-time treatments for rare genetic diseases. Experts cautioned that durability, safety and cost must still be proven, but hailed the work as a milestone showing gene-editing promises are “coming to fruition” for patients in years ahead.
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