Baby with rare disease given world-first personal CRISPR gene therapy
An infant with a severe genetic condition has shown signs of improvement after receiving a gene-editing treatment tailored to his specific mutation
By Michael Le Page
15 May 2025
Baby KJ after a gene-editing infusion with researchers Rebecca Ahrens-Nicklas and Kiran Musunuru
Children’s Hospital of Philadelphia
A baby boy with a life-threatening genetic condition has become the first person to receive a bespoke CRISPR gene-editing treatment, giving a glimpse into what the future of medicine might look like.
It’s the first time anyone has been given a gene-editing treatment designed to correct a disease-causing mutation found only in that individual, Rebecca Ahrens-Nicklas at the Children’s Hospital of Philadelphia, Pennsylvania, told a press briefing. “He’s showing some early signs of benefit,” she says, but it is too soon to tell how well the treatment worked.
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The researchers published the details as soon as possible in the hope that it will inspire others, says team member Kiran Musunuru at the University of Pennsylvania. “We very much hope that showing that it’s possible to make a personalised gene-editing therapy for a single patient in several months will inspire others to do the same,” he says.
“I don’t think I’m exaggerating when I say that this is the future of medicine,” he says. “This is the first step towards the use of gene-editing therapies to treat a wide variety of rare genetic disorders for which there are actually very few treatments currently in development at all.”
The boy, KJ, inherited mutations in each of his two copies of a gene for a liver enzyme called CPS1. Without this enzyme, ammonia builds up in the blood when proteins, including ones we eat, are broken down, damaging the brain. More than half of children born with a CPS1 deficiency die, says Ahrens-Nicklas.
