KJ received the first dose through an infusion in February, followed by two additional doses in March and April. Doctors reported that he is doing well but will require ongoing, lifelong monitoring.
Doctors in the United States have become the first to treat a baby using a customised gene-editing therapy, following the diagnosis of a rare and life-threatening genetic disorder that typically proves fatal in early infancy for nearly half of those affected.
The achievement, praised by international researchers as a major medical milestone, highlights the potential of personalised gene editing to address a wide range of severe genetic conditions shortly after birth by correcting faulty DNA, The Guradian reported.
Specialists at the Children’s Hospital of Philadelphia and the University of Pennsylvania began developing the treatment immediately after diagnosing the child, named KJ, with the condition. Within six months, they completed the complex process of designing, producing and safety testing the bespoke therapy.
KJ received the first dose through an infusion in February, followed by two additional doses in March and April. Doctors reported that he is doing well but will require ongoing, lifelong monitoring.
Dr Rebecca Ahrens-Nicklas, a senior physician on the team, said the breakthrough was the result of “years and years of progress” in the field of gene editing. “While KJ is just one patient, we hope he is the first of many to benefit,” she said.
KJ was diagnosed with a severe form of CPS1 deficiency, a rare genetic disorder that affects around one in 1.3 million people. The condition prevents the liver from producing an enzyme essential for converting ammonia, a natural byproduct of protein breakdown, into urea for safe excretion. The resulting ammonia build-up can severely damage the liver and brain.
Liver transplants are sometimes used to treat CPS1 deficiency, but for infants with the most severe form, surgery often comes too late to prevent lasting harm.
In a report published in the *New England Journal of Medicine*, the medical team detailed the process of pinpointing the exact genetic mutations causing KJ’s condition, designing a gene-editing solution to correct them and developing the fatty nanoparticles required to deliver the therapy to the liver. The treatment used a precise technique known as base editing, which allows DNA to be rewritten one letter at a time.
KJ spent the first few months of his life in hospital, maintained on a strict diet to limit protein intake. Since the gene therapy, doctors have been able to safely increase the protein in his diet and reduce the amount of medication needed to control nitrogen levels in his body. The promising early results were presented at the annual meeting of the American Society of Gene and Cell Therapy in New Orleans.
Though further monitoring is essential to evaluate the long-term success of the treatment, the initial signs are encouraging.