For the first time ever, a patient has received personalized gene editing treatment to combat a rare disease. This groundbreaking treatment was provided to baby KJ, who suffers from a CPS1 deficiency. This could change the face of healthcare forever.
At just nine months old, KJ became the first patient — of any age — to undergo personalized gene editing treatment. This historic moment was revealed on May 15th in the New England Journal of Medicine, following the procedure at the Children’s Hospital of Philadelphia. KJ had a rare genetic disorder called carbamoyl-phosphate synthase deficiency (CPS1), a condition affecting just one in 1.3 million births.
Half of Affected Babies Don’t Survive
CPS1 deficiency is caused by mutations in a gene responsible for an enzyme crucial to liver function. Without this enzyme, patients can’t clear certain toxic substances like ammonia from their system. This buildup can cause brain damage or death. Typically, a liver transplant is necessary, but only about half of babies with this condition survive long enough to receive one. The disease also often leads to developmental and cognitive delays.
Doctors prescribed KJ medication to help him eliminate ammonia and a strict low-protein diet. However, it would take months for KJ to qualify for a transplant, and every day that passed brought an increased risk of brain damage or death. That’s when Rebecca Ahrens-Nicklas, a researcher working on base editing (a CRISPR-based technology that won the 2020 Nobel Prize in Chemistry), offered an alternative treatment to KJ’s parents.
Base Editing: A First for Human Testing
While CRISPR technology allows scientists to cut DNA at specific locations, many previous applications have been for genetic diseases affecting many people, even if the mutations vary. However, KJ’s treatment required adapting the method to fix a specific genetic sequence. The goal was to make precise alterations to just one DNA letter, correcting a single error rather than cutting both strands of DNA. This is the power of base editing.
After decades of research, this technology had never been tested on humans. Rebecca Ahrens-Nicklas, a pediatrician at the Children’s Hospital of Philadelphia, believed it was time. She presented the solution to KJ’s parents, who agreed. In just six months, an international team of researchers and clinicians developed the personalized treatment. The mutation was corrected once the treatment reached KJ’s liver, encapsulated in lipid molecules to protect it from degradation in the bloodstream.
An Unprecedented Speed of Development
Typically, such a development would take years. Fyodor Urnov, a professor of molecular therapeutics at UC Berkeley and scientific director of the Innovative Genomics Institute, stated, “This speed in replicating clinical-grade CRISPR for a genetic disease is unprecedented in our field.”
The first infusion, at a very low dose, took place on February 25th. Afterward, KJ could consume as much protein as a healthy baby, although he still needed the medication. A second infusion occurred 22 days later, and KJ responded positively. The medication dose was reduced by half, and he “easily overcame” viral infections that would have caused ammonia spikes. A third infusion has recently been administered. While it’s too soon to call it a cure, KJ shows “early signs of benefit.”
A Groundbreaking Shift in Healthcare
Although it’s difficult to put a price on KJ’s treatment, as many companies contributed without charge, this method has the potential to transform healthcare. It could be adapted to correct genetic mutations, offering hope to many with rare diseases. Kiran Musunuru from the University of Pennsylvania expressed optimism: “Demonstrating the possibility of developing personalized gene-editing therapy for a single patient in just a few months will likely encourage others to follow suit.”
Lucie Petit
Journalism student
I’ve been passionate about science since childhood, growing up in the countryside with a strong love for nature. Inspired by my grandfather’s inventive spirit, I developed a curiosity for understanding and sharing knowledge. After earning a science-focused diploma, I chose journalism to make complex topics accessible. I’m now studying at ISCPA in Lyon and interning at Futura, where I’m excited to turn this passion into a profession.
