In a medical milestone that sounds like science fiction, doctors have successfully edited a baby's genes inside the body to treat a rare and deadly genetic disease—marking the first time such a personalized approach has been used in a human being.
Meet KJ: A Race Against Time
The patient, known as KJ, was born with carbamoyl phosphate synthetase 1 (CPS1) deficiency, a rare and often fatal condition that prevents the body from breaking down nitrogen. This defect causes a dangerous buildup of ammonia in the blood, which can lead to brain damage, coma, or even death.
For most babies with CPS1 deficiency, liver transplant is the only chance of survival. But KJ’s doctors at the Children’s Hospital of Philadelphia and researchers at the University of Pennsylvania had a different idea: Could they fix the problem at its source—the DNA inside his liver cells?
A Custom-Made Genetic Fix
Using CRISPR, the gene-editing tool often described as “molecular scissors,” the team created a custom treatment tailored specifically to KJ’s unique mutation. Unlike standard gene therapy, which delivers a working copy of a gene, this approach aimed to correct the faulty gene directly inside KJ’s liver.
To do this, the scientists packaged the CRISPR editor into tiny lipid nanoparticles—fat-like bubbles that can carry genetic instructions into cells. These were injected into KJ’s bloodstream, where they traveled to his liver and began repairing the faulty gene.
What Happened Next?
After the treatment, something extraordinary occurred: KJ's ammonia levels dropped and stabilized, a sign that his liver was starting to function properly. No transplant was needed. As of the most recent reports, KJ is doing well, showing signs of normal development—something that would have been unthinkable just a few years ago.
This success is the first-ever example of patient-specific, in vivo gene editing, meaning the therapy was:
-
Custom-designed for one individual’s genetic mutation
-
Delivered directly into the body
-
Able to correct the DNA inside living cells
Why This Matters
This case represents more than a medical marvel—it’s a blueprint for the future of personalized medicine.
If this approach can be applied to other rare diseases, it could change the lives of thousands of patients for whom there are currently no treatments. There are over 7,000 rare genetic conditions, many affecting only a handful of people worldwide. This method could offer hope to those long overlooked by traditional drug development.
A Word of Caution
While the results are promising, this treatment is still experimental. Long-term effects are unknown, and such a custom therapy is extremely complex and costly. It also raises questions about equity and access—will only a few be able to afford this kind of care?
Looking Ahead
Still, for KJ and his family, this scientific first is deeply personal—and profoundly hopeful. A baby once facing certain death now has a chance at a normal life, thanks to the power of gene editing and the dedication of scientists who believed it could be done.
References
1.Patient-Specific in Vivo Gene Editing to Treat a Rare Genetic Disease | New England Journal of Medicine, www.nejm.org/doi/full/10.1056/NEJMoa2504747. Accessed 16 May 2025.
2. Park, Alice. “A Baby Was Dying. Then Gene Editing Changed Everything.” TIME, 8 May 2024, https://time.com/7285695/first-crispr-treatment-baby/.
3. Children’s Hospital of Philadelphia. “CHOP Researchers Announce First In Vivo CRISPR Gene Editing Therapy for CPS1 Deficiency.” CHOP Newsroom, May 2024, https://www.chop.edu/news.
4. Broad Institute of MIT and Harvard. “CRISPR: A Game-Changing Genetic Engineering Technique.” Broad Institute, https://www.broadinstitute.org/what-broad/areas-focus/project-spotlight/crispr. Accessed 16 May 2025.
Add comment
Comments