Three-year-old Oliver Chu has stunned clinicians after becoming the first person with Hunter syndrome (MPS II) to receive an experimental gene therapy and showing striking early gains. Hunter syndrome is a rare, X-linked disorder that progressively damages the body and brain, often leading to severe cognitive decline and shortened lifespan. Oliver lacked iduronate-2-sulfatase (IDS), an enzyme needed to break down certain complex sugars; without it, toxic buildup harms organs and the central nervous system.
As reported by the BBC, in December 2024, at Royal Manchester Children’s Hospital, Oliver began a one-time, stem cell–based gene therapy. Clinicians harvested his blood stem cells and shipped them to Great Ormond Street Hospital in London, where scientists inserted a functional IDS gene into the cells using a virus engineered as a delivery vehicle. To address the crucial challenge of brain involvement, the gene was modified so the resulting enzyme could cross the blood-brain barrier more efficiently. In February 2025, Oliver received two infusions totaling about 125 million modified cells, intended to repopulate his bone marrow and continuously produce the missing enzyme.
By May, early signs were striking. Oliver became more mobile and communicative, and crucially, he was able to stop weekly enzyme infusions—previously the only treatment, Elaprase, which cannot reach the brain and costs around £300,000 per year. His parents, Jingru and Ricky, reported rapid gains in speech, agility, and engagement with other children. Nine months after treatment, tests confirmed he was producing “hundreds of times” the normal IDS enzyme levels, according to trial co-lead Prof Simon Jones, who nonetheless urged cautious optimism as long-term monitoring continues.
Oliver’s progress is especially poignant for his family because his older brother, Skyler, also has Hunter syndrome and currently receives enzyme replacement that treats the body but not the brain. The family hopes the new approach could be extended to him. Oliver returns to Manchester every three months for follow-up evaluations, with continued improvements noted in learning and motor skills.
This first-in-human trial nearly didn’t happen. After years of development at the University of Manchester led by Prof Brian Bigger, a planned partnership faltered when the biotech sponsor withdrew. Emergency funding from the UK medical research charity LifeArc—£2.5 million—rescued the study. Five boys from the US, Europe, and Australia are now enrolled, each to be followed for at least two years. If successful, the hospital and university aim to partner with industry to pursue licensing. Similar strategies are being tested for related lysosomal storage disorders, including MPS I (Hurler syndrome) and MPS III (Sanfilippo syndrome).
For Oliver, the impact is already life-changing: less time tethered to hospitals, more time running, talking, and learning. As his father puts it, his development hasn’t just inched forward—it has surged since the transplant. While much remains to be proven, Oliver’s story signals a potential paradigm shift for Hunter syndrome and a beacon of hope for families facing rare, devastating genetic diseases.
