A three-year-old boy with Hunter syndrome has amazed doctors by thriving after becoming the first person in the world to receive a pioneering gene therapy, showing normal development and producing his own enzymes for the first time. Oliver Chu, from California, was diagnosed with Hunter syndrome, a rare genetic disorder that causes progressive damage to the body and brain, often leading to death before age 20. The condition results from a faulty gene that prevents the production of an essential enzyme, iduronate-2-sulfatase (IDS), leading to accumulated sugars in tissues.
The world-first treatment involved a complex process starting in December 2024 with the removal of Oliver’s stem cells at Royal Manchester Children’s Hospital. These cells were sent to Great Ormond Street Hospital in London, where scientists inserted a working copy of the IDS gene using a modified virus. In February 2025, Oliver received an infusion of his gene-edited stem cells back into his body. The procedure was quick, taking about 10 minutes per infusion, and aimed to repopulate his bone marrow with cells capable of producing the missing enzyme.
By May 2025, Oliver’s progress was evident; he had improved speech and mobility, and crucially, he was able to stop weekly enzyme infusions as his body began producing IDS on its own. His mother, Jingru, expressed overwhelming joy at the transformation, noting that he is talking more and engaging with other children. The Chu family, including Oliver’s older brother Skyler who also has Hunter syndrome, hopes that Skyler can eventually receive the same treatment. Currently, Skyler relies on enzyme replacement therapy, which does not cross the blood-brain barrier and thus does not address cognitive decline.
The clinical trial includes five boys from the US, Europe, and Australia, all monitored for at least two years. If successful, the treatment could be licensed, offering hope for others with similar rare diseases. The trial faced funding challenges initially, with a biotech partner withdrawing, but was saved by a £2.5 million grant from LifeArc, a British medical research charity. Researchers have worked on this therapy for over 15 years, led by Prof Brian Bigger at the University of Manchester.
This breakthrough not only highlights the potential of gene therapy for rare conditions but also underscores the importance of persistent research and funding. Oliver’s story represents a significant step forward in treating genetic disorders, with implications for future medical innovations that could benefit millions worldwide.
