A three‑year-old boy has become the first patient to receive a groundbreaking stem-cell gene therapy for Hunter syndrome, a rare and life-limiting genetic disorder, offering new hope for children born with the disease. The treatment was given in February 2025 at Royal Manchester Children’s Hospital in a clinical study run by the University of Manchester and the Manchester Centre for Genomic Medicine.
Hunter syndrome, also known as mucopolysaccharidosis type II (MPS II), prevents the production of a critical enzyme (iduronate-2-sulfatase) needed to break down complex sugar molecules. Without this enzyme, these sugars accumulate in organs and tissues, leading to joint problems, heart and breathing issues, hearing loss, and neurological decline.
In the procedure, doctors first removed the child’s stem cells, genetically corrected them to include a working copy of the faulty gene, and then re‑infused them into his body. The therapy was manufactured by Great Ormond Street Hospital using a viral vector to deliver the functional gene into the patient’s own cells.
Several months after the treatment, the boy has reportedly recovered well and is producing the missing enzyme. His parents and the research team say they are encouraged by his gains in physical and cognitive development and by the fact that he may no longer require regular enzyme infusions.
The therapy was funded by LifeArc, a non‑profit research organisation, and is part of a study involving five young boys with Hunter syndrome.
Researchers say the approach could pave the way for safer and more effective treatments for other rare genetic disorders.
The current standard treatment for Hunter syndrome is weekly enzyme replacement therapy, which helps reduce some physical symptoms but cannot address neurological decline.
The trial is being closely monitored and outcomes in other children will be important to determine whether this therapy could become a long-term treatment option for Hunter syndrome.
