First baby treated with new gene therapy
May 27, 2025
Summary: A new type of genetic therapy that is less dangerous and can be repeated was used for a baby with a lethal genetic disease. It will still be years before this technology is available outside of clinical trials.
The New England Journal of Medicine reported last week about the first infant treated with CRISPR 2.0 gene therapy. The baby, KJ Muldoon, was born with a life-threatening genetic defect of the urea cycle (CSPI deficiency), which means that he did not have the ability to detoxify ammonia-type waste products. Untreated, this disease would lead to coma, brain damage and death, and there is no good available treatment.
Researchers designed a “bespoke” genetic therapy to insert the correct proteins into his genes so that he would be able to produce the deficient enzyme. The genetic therapy was administered through mRNA technology, which is a substantial advance over CRISPR 1.0 therapy, such as that now available for hemophilia and sickle cell disease. The injection is given directly to the patient, and there is no need to destroy the bone marrow (which leads to many dangers and long hospitalizations with previous gene therapies). mRNA infusions can be repeated, whereas genetic therapy delivered through a weakened virus can generally only be given once, after which the body’s immune system will attack the genetic therapy.
KJ is doing well at 9½ months, although only time will tell if the genetic therapy benefit endures over time. If you’re interested in more detail, Eric Topol of the Scripps Institute has an excellent description of this procedure in his Substack.
This could be a template for treatment of many other genetic diseases, and the approach could be streamlined and thus more widely available than current gene therapies.
Implications for employers:
Like most new groundbreaking therapies, it will likely take years before CRISPR 2.0 therapy is available widely, as researchers enroll more people into clinical trials and watch for unexpected side effects and assess long term outcomes.
The ability to correct a defective gene without the danger and harm of fully suppressing the bone marrow represents an exciting new advance in genetic therapy.
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