Baby receives world's first personalized genetic treatment

A baby suffering from a rare and incurable disease has become the first patient in the world to benefit from personalized gene therapy, a promising feat for other pathologies, an American medical team announced on Thursday (15).

KJ Muldoon, a round-faced, blue-eyed nine-month-old baby, was diagnosed shortly after birth with a very rare and serious metabolic disorder called carbamoyl phosphate synthetase deficiency, or CPS1.

This disease is caused by mutations in a gene that encodes an enzyme crucial to liver function, and prevents those affected from eliminating certain toxic substances produced by metabolism, such as ammonia generated when proteins break down.

“When you Google what CPS1 is, it’s either death or liver transplant,” Nicole Muldoon, the boy’s mother, said in a video from the Children’s Hospital of Philadelphia in the United States, where the baby is being treated.

The medical team proposed testing something new: a personalized therapy based on the use of molecular scissors (Crispr-Cas9), a revolutionary technology, awarded the Nobel Prize in Chemistry in 2020, which allows genome editing.

“Our son was sick. We had to either do a liver transplant or give him this medicine that has never been given to anyone,” recalls Kyle, the baby’s father.

Despite their fears, the couple agreed, and the child received the medicine in February, and twice more after that.

“The drug is designed exclusively for KJ, so the genetic variants he has are specific to him. It’s personalized medicine,” explains Dr. Rebecca Ahrens-Nicklas, a pediatric genetics specialist.

Once in the liver, the microscopic scissors contained in the administered solution penetrate the nucleus of the cells and attempt to modify the gene in question.

It is a treatment with promising results, according to the medical team, which published a study on the subject this Thursday in the New England Journal of Medicine.

KJ is now tolerating a higher-protein diet and requires less medication, but long-term follow-up is needed “to assess the safety and efficacy of the treatment,” she says.

Ahrens-Nicklas hopes this achievement will allow the boy to live “with very little or no medication” and that the experience can be useful to others.

“We hope he will be the first of many to benefit from a methodology that can be adapted to the needs of each patient,” he said.