Infant Is First To Successfully Receive Personalized Gene Therapy

In a groundbreaking medical achievement, an infant from Pennsylvania, referred to as KJ, has become the first person to successfully receive a personalized CRISPR gene editing therapy. The treatment was developed by a team at the Children's Hospital of Philadelphia (CHOP) and Penn Medicine to address KJ's severe carbamoyl phosphate synthetase 1 (CPS1) deficiency, a rare metabolic disorder.

KJ was diagnosed with CPS1 deficiency shortly after birth, a condition that prevents the conversion of ammonia to urea, leading to toxic ammonia levels in the body. Typically, such conditions are managed with liver transplants, but KJ was too young for the procedure. Instead, researchers developed a customized gene editing therapy specifically targeting KJ's genetic variant.

The therapy, administered in February 2025 when KJ was between six and seven months old, involved using lipid nanoparticles to deliver the gene editing treatment directly to the liver. Since the treatment, KJ has shown significant improvement, tolerating more dietary protein and reducing reliance on nitrogen scavenger medication. He has also been able to recover from common childhood illnesses without ammonia buildup.

Dr. Rebecca Ahrens-Nicklas and Dr. Kiran Musunuru, who led the research, hope this success will pave the way for similar treatments for other rare diseases.

"While KJ will need to be monitored carefully for the rest of his life, our initial findings are quite promising," said Dr. Ahrens-Nicklas.

The study detailing KJ's treatment was published in the New England Journal of Medicine and presented at the American Society of Gene & Cell Therapy Annual Meeting in New Orleans. The success of this personalized therapy marks a significant step forward in the field of gene editing, offering hope to many families affected by rare genetic disorders.