In a groundbreaking medical achievement, a team of doctors and researchers successfully administered a customized CRISPR gene therapy to an infant born with a life-threatening genetic disorder. The treatment was delivered just six and a half months after birth, marking a significant milestone in the field of genetic medicine.

The child, KJ Muldoon, was diagnosed shortly after birth with mutations in both copies of the gene for the enzyme carbamoyl phosphate synthetase 1 (CPS1). This deficiency prevents the breakdown of ammonia in his body, leading to potential liver damage and neurological issues. Typically, such conditions require a liver transplant for survival.

The University of California, Berkeley’s Innovative Genomics Institute (IGI) collaborated with physicians at the Children’s Hospital of Philadelphia (CHOP) to develop and test this bespoke CRISPR base-editing therapy. The U.S. Food and Drug Administration fast-tracked its approval following successful safety tests conducted by IGI's team.

“This was a remarkable team effort,” stated Jennifer Doudna, founder of IGI. “The ability to develop an on-demand CRISPR therapy in such a short time opens up a new era for treating previously untreatable genetic diseases.”

Fyodor Urnov from IGI emphasized the collaborative nature of this success: “A remarkable multi-institution team — CHOP, Penn, IGI/UC Berkeley — came together to show that one can create a CRISPR on-demand therapy in six months.”

Dr. Rebecca Ahrens-Nicklas from CHOP expressed hope for broader applications: “While KJ is just one patient, we hope he is the first of many to benefit from a methodology that can be scaled to fit an individual patient’s needs.”

As part of ongoing monitoring since February 2025 when KJ received his first dose, doctors have observed positive outcomes without serious side effects. His parents shared their relief at seeing their son thrive: “We’re so excited to be able to finally be together at home,” said Kyle Muldoon.

Further studies are required to fully understand the long-term benefits and potential scalability of this treatment approach.