A three-year-old boy named Oliver Chu has shown remarkable progress after becoming the first person in the world to receive a pioneering gene therapy for Hunter syndrome, a rare and devastating genetic disorder. The one-off treatment, administered in Manchester, has enabled him to produce his own missing enzyme, potentially halting the disease’s progression and offering hope for similar conditions.
Hunter syndrome, also known as MPSII, is an inherited condition caused by a faulty gene that prevents the body from producing the enzyme iduronate-2-sulfatase (IDS). This enzyme is crucial for breaking down complex sugar molecules, which accumulate in tissues and organs over time, leading to progressive damage to the heart, liver, bones, and brain. In severe cases, it causes symptoms resembling childhood dementia and typically reduces life expectancy to 10–20 years. Until now, the only available treatment was Elaprase, a weekly infusion costing around £375,000 per year that slows physical symptoms but cannot prevent cognitive decline as it does not cross the blood-brain barrier.
The gene therapy involved collecting stem cells from Oliver’s blood in December 2024 and sending them to a laboratory at Great Ormond Street Hospital in London. There, scientists used a modified virus to insert a working copy of the faulty IDS gene into the stem cells. The gene-edited cells were then re-infused into Oliver’s bloodstream in February 2025 during a brief procedure. This one-off treatment is designed to allow the corrected cells to repopulate the bone marrow and continuously produce the missing enzyme, with a modified version that efficiently crosses the blood-brain barrier to address both physical and cognitive symptoms.
Nine months post-treatment, Oliver has astounded doctors with his rapid improvement. He no longer requires weekly Elaprase infusions, as his body is now producing high levels of the enzyme on its own. His speech, mobility, and cognitive development have advanced dramatically; he is more inquisitive, engaging with other children, and showing normal developmental milestones. Prof Simon Jones, who co-leads the trial, described Oliver’s progress as ‘exciting,’ noting that he is making hundreds of times the normal amount of enzyme and acquiring new skills, though long-term monitoring is still essential.
Oliver’s parents, Ricky and Jingru, expressed overwhelming gratitude and relief, describing him as a ‘completely different child’ whose life is no longer dominated by hospital visits and needles. They hope the therapy will eventually be available for their older son, Skyler, who also has Hunter syndrome but was diagnosed too late for this trial. Skyler, now five, shows delayed development but remains largely unaffected, and the family is advocating for expanded access to the treatment. Ricky emphasized that Oliver’s improvements have been exponential since the transplant, far exceeding gradual age-related changes.
The trial includes five boys from the US, Europe, and Australia, all of whom will be monitored for at least two years to assess the therapy’s long-term efficacy and safety. None are from the UK, as patients there are often diagnosed too late due to the lack of newborn screening for Hunter syndrome. If successful, the researchers plan to partner with a biotech firm to license the treatment, which could also be adapted for other genetic disorders like Hurler syndrome and Sanfilippo syndrome, currently under trial in Manchester.
This breakthrough nearly faltered due to funding challenges; after a previous partner withdrew, the British charity LifeArc provided a £2.5 million grant to salvage the trial. The success highlights the critical role of investment in rare disease research, which affects over 3.5 million people in the UK alone, 95% of whom lack effective treatments. The gene therapy approach represents a significant advancement in medical science, potentially transforming the lives of children with rare genetic conditions and setting a precedent for future innovations.
Looking ahead, the medical team remains cautiously optimistic, emphasizing the need for continued evaluation before broader application. For now, Oliver’s story serves as a beacon of hope, demonstrating the potential of gene therapy to address previously untreatable diseases and improve quality of life. As research progresses, this could pave the way for more accessible and affordable treatments, reducing the burden on families and healthcare systems worldwide.
