Three-year-old Oliver Chu from California received a one-off gene therapy nine months ago at Royal Manchester Children's Hospital. He no longer needs the weekly enzyme infusions that once dominated his childhood. His father describes the shift as sudden: speech, movement, and cognitive development have accelerated dramatically since the procedure.
Hunter syndrome is caused by a faulty gene that stops the body making an enzyme to break down complex sugar molecules. Without treatment, the condition leads to joint stiffness, hearing loss, heart problems, and cognitive decline—typically shortening life to between 10 and 20 years.
The therapy works by extracting stem cells from a patient's blood, inserting a working copy of the gene, and reinfusing the corrected cells. It's a one-time procedure, not an ongoing treatment. Oliver was the first human to receive it, making the nine-month window of observation still early. But the signs matter: he's come off the weekly infusions that once structured his entire life around hospital visits and needles.
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Start Your News Detox"Things look really hopeful right now," says Prof Simon Jones, the paediatric metabolic disease consultant leading the trial at Manchester Centre for Genomic Medicine. "But Ollie was the first human to receive this therapy and it's only been nine months out." The caution is deliberate. Gene therapies can take years to show their full effects—both benefits and potential complications.
Scaling the approach
The same technique is now being adapted for other genetic disorders where missing enzymes cause damage: Hurler syndrome, Sanfilippo syndrome, and others. The Manchester team is also running a trial with five boys from the US, Europe, and Australia.
But there's a bottleneck. The therapy works best when given early, ideally before organ damage accumulates. In the US, newborn screening for Hunter syndrome is standard—a heel prick test catches the condition days after birth. In the UK and most of Europe, it isn't. Oliver was diagnosed only after symptoms emerged, meaning some damage had already occurred. His elder brother Skyler, also affected, is five and largely unaffected so far—young enough that earlier intervention could potentially prevent the worst outcomes entirely.
For this therapy to reach most patients, newborn screening would need to become routine. It's a policy question as much as a medical one. The science is moving faster than the infrastructure to deliver it.
Oliver's case shows what's possible when both timing and treatment align. His parents are hopeful the therapy might eventually help Skyler too, catching the condition before it takes hold.
