A three-year-old boy named Oliver Chu, who suffers from a rare inherited condition called Hunter syndrome (Mucopolysaccharidosis type II or MPS II), has made astonishing progress after becoming the first person globally to receive a groundbreaking gene therapy in Manchester. This revolutionary treatment, developed over 15 years by researchers at The University of Manchester, offers new hope for patients worldwide grappling with this life-limiting disorder.

Hunter syndrome is a severe genetic disorder that almost exclusively affects boys. It results from a faulty gene that prevents the body from producing a crucial enzyme, iduronate-2-sulfatase (IDS), necessary for breaking down large sugar molecules. Without this enzyme, these sugar molecules accumulate progressively in tissues and organs, leading to widespread damage to the body and brain. Medics have likened its effects to a form of childhood dementia, causing issues such as joint stiffness, hearing loss, breathing and heart problems, developmental delays, and severe mental decline. In its most severe form, most patients tragically do not survive past the age of 20. The current standard treatment, an enzyme replacement therapy called Elaprase, requires weekly, three-hour infusions for life and, while it can alleviate some physical symptoms, it does not prevent mental decline, costing approximately £375,000 per patient annually.

In a world-first clinical trial, medical staff at the Royal Manchester Children's Hospital (RMCH) embarked on a mission to halt the disease's progression by altering Oliver's cells using gene therapy. The process began in December 2024 with the removal of Oliver's stem cells at the Manchester children's hospital. These cells were then meticulously packaged and sent to a specialized laboratory at Great Ormond Street Hospital (GOSH) in London. There, scientists inserted a working copy of the missing IDS gene into a modified virus, which acted as a vehicle to deliver the gene into Oliver's stem cells. Crucially, the inserted gene was engineered to produce an enzyme capable of crossing the blood-brain barrier more efficiently, a significant advancement over previous treatments.

In February 2025, Oliver returned to RMCH for the re-infusion of his genetically modified cells. The procedure, involving two identical infusions an hour apart, took only about 10 minutes. This one-off procedure aims for the modified stem cells to repopulate his bone marrow, producing new white blood cells that continuously generate the missing enzyme throughout his body and brain. Following the successful gene therapy, Oliver and his family, originally from California, were able to fly home.

The progress observed in Oliver since the treatment has astounded both doctors and his family. Crucial tests in May confirmed the gene therapy was working. Oliver's father, Ricky, reported dramatic improvements in his speech, mobility, and cognitive development.