Three-year-old Oliver Chu has become the face of a medical breakthrough that is sending ripples of hope through families affected by rare genetic disorders worldwide. On November 24, 2025, Oliver became the first patient ever to receive a pioneering gene therapy for Hunter syndrome, a devastating inherited disease that damages both body and brain. The treatment, developed and trialed by doctors in Manchester, has shown such remarkable results that experts are calling it a turning point in the fight against childhood dementia and similar conditions.
Hunter syndrome, also known as MPSII, is a rare lysosomal storage disorder that almost exclusively affects boys, with an incidence of about one in every 100,000 male births globally, according to the Cleveland Clinic. The disorder is caused by a faulty gene that prevents the body from producing a crucial enzyme needed to break down certain sugar molecules. Without this enzyme, these sugars accumulate in organs and tissues, leading to progressive damage—affecting the heart, liver, bones, joints, and, in severe cases, causing mental disability and a decline in the nervous system. Most children with the most severe form of the disease do not live beyond their teenage years, and the symptoms, which can include changes in facial features, stiff limbs, and short stature, typically begin around age two.
Oliver’s journey began in California, where he was diagnosed with Hunter syndrome at age two. His parents, Ricky and Jingru, faced a grim prognosis not only for Oliver but also for his older brother Skyler, who shares the same diagnosis. "When you find out about Hunter syndrome, the first thing the doctor tells you is, ‘Don’t go on the internet and look it up because you’ll find the worst cases and you’ll be very, very disheartened’," Ricky Chu told The Times. But like most parents, they did their own research—"Oh my goodness, is this what’s going to happen to both my sons?" Ricky recalled.
In 2024, the family traveled to the UK to participate in a world-first clinical trial at Royal Manchester Children's Hospital. The trial was led by Professor Simon Jones and Professor Brian Bigger, whose team at the University of Manchester had spent over 15 years developing the gene therapy, with crucial funding from the charity LifeArc. The therapy’s scientific foundation was years in the making and almost faltered when a biotech partner withdrew support, but the researchers persevered.
The treatment itself is a feat of modern medicine. Doctors first collected Oliver’s stem cells from his blood, then sent them to Great Ormond Street Hospital in London. There, Dr. Karen Buckland and her team used a viral vector to insert a working copy of the faulty gene into each stem cell. "We use the machinery from the virus to insert a working copy of the faulty gene into each of the stem cells. When those go back to Oliver, they should repopulate his bone marrow and start to produce new white blood cells, and each of these will hopefully start to produce the missing protein [enzyme] in his body," Dr. Buckland explained to BBC.
Once the cells were modified, they were frozen and transported back to Manchester. In February 2025, the team carefully thawed the cells and infused approximately 125 million gene-modified stem cells into Oliver through a catheter in his chest. The entire process, which included two infusions in one day, took less than an hour. The inserted gene was specially engineered to help the enzyme cross the blood-brain barrier, a crucial step in preventing the neurological decline seen in Hunter syndrome.
After the procedure, Oliver returned home to California, where his parents anxiously waited for signs that the therapy was working. The first follow-up came in May, when the family returned to Manchester for testing. The results were nothing short of dramatic. Oliver was more mobile, alert, and communicative—milestones that had seemed out of reach just months earlier. Ricky Chu shared, "He’s doing really well. We have seen him progressing in his speech, and mobility. In just three months he has matured." His mother, Jingru, was overcome with emotion: "Every time we talk about it I want to cry because it’s just so amazing."
By late August, the gene therapy’s success was confirmed. Oliver no longer needed the weekly enzyme infusions that had been the standard, but limited, treatment for Hunter syndrome. Instead, his own body was producing hundreds of times the normal amount of the vital enzyme. Professor Simon Jones, who had dedicated two decades to this moment, told the BBC, "I’ve been waiting 20 years to see a boy like Ollie doing as well as he is, and it’s just so exciting." He added, "Before the transplant Ollie didn’t make any enzyme at all and now he’s making hundreds of times the normal amount."
The transformation in Oliver has astonished his doctors and given his family hope for the future—not just for him, but also for his brother Skyler and countless others. Ricky Chu said, "He’s like a completely different child. He’s running around everywhere, he won’t stop talking. The future for Ollie seems very bright and hopefully this means more kids will get the treatment." The Chu family is "eternally grateful" to the research team and the charity supporters who made the trial possible. "I would walk to the end of the earth to make sure my kids have a better future," Ricky said.
The trial includes five boys from the US, Europe, and Australia, and will continue for at least two years. If the results hold, the therapy could move toward licensing and become a template for treating other related conditions, such as Hurler syndrome and Sanfilippo syndrome. Professor Jones emphasized the importance of early intervention: "For this trial, we wanted to treat children really early, because we thought that would give them the best chance of a normal outcome." He acknowledged the heartbreak of families who were diagnosed too late for the trial, saying, "There are lots of tragic stories that are part of this success."
Before this breakthrough, the only available treatment for Hunter syndrome was Elaprase, an enzyme replacement therapy costing around £300,000 per year per patient. While the new gene therapy is still expensive and in its early days, experts believe it could ultimately save lives and reduce the long-term costs associated with the disease.
Oliver’s story is a testament to scientific perseverance, the power of hope, and the promise of gene therapy for rare diseases. As his parents watch him thrive, they—and many others—now dare to dream of a future where children with Hunter syndrome can look forward to long, healthy lives.
