India, May 15 -- In a groundbreaking medical first, doctors have used a personalized gene-editing therapy to treat an infant suffering from a rare and deadly genetic disorder, offering new hope for patients with ultra-rare diseases.

KJ Muldoon, born in August 2024, was diagnosed with CPS1 deficiency, a severe metabolic disorder that prevents the body from breaking down protein, leading to dangerous ammonia buildup. Half of all infants with the condition die within the first week of life. Traditional treatments such as ammonia-lowering drugs offer only limited benefit, and liver transplants are delayed until the child is at least one year old-often too late to prevent lasting brain damage.

Faced with this urgency, researchers at the Childr...