Months after receiving a one-time gene therapy, three-year-old Ollie Chaw, who suffers from the rare Hunter syndrome, is showing remarkable improvement. This experimental treatment, which relies on modifying the child’s own cells, opens up new horizons for treating devastating genetic diseases.
Article Contents:
- Ollie’s Story: New Hope in the Fight Against a Rare Disease
- What Is Hunter Syndrome?
- Current Treatments and Their Limitations
- The New Gene Therapy: How Does It Work?
- The Cellular Waste Problem and the IDS Enzyme
- Full Replacement: Medical Procedure Details
- Remarkable Recovery and Return to Childhood
- Next Steps and the Future of Treatment
- Frequently Asked Questions
Ollie’s Story: New Hope in the Fight Against a Rare Disease
Ollie Chaw was three years old when he received an intravenous injection that changed the course of his life. Ollie was born with a rare genetic condition called Hunter syndrome, which prevents his body from producing an enzyme necessary to break down complex sugars. This groundbreaking gene therapy, developed at the University of Manchester, represents a massive leap in modern medicine.
What Is Hunter Syndrome?
Just a few months after his birth, sugars began to accumulate everywhere in Ollie’s body, causing severe damage to his lungs, liver, skin, and brain. In Hunter syndrome, joints stiffen and airways narrow, making breathing difficult. The brain also struggles to develop, leading to developmental delays and cognitive issues. Unfortunately, most children diagnosed with this condition do not live past the age of twenty.
Current Treatments and Their Limitations
There are very few treatments available. One drug on the market treats certain physical symptoms but is extremely expensive, must be taken weekly for life, and cannot save the brain from damage. The other option is a complete bone marrow replacement. Although this provides a long-term solution, the procedure is fraught with risk for young children and relies on the availability of matched donors, who are very scarce.
The New Gene Therapy: How Does It Work?
Ollie’s new treatment is different. About a year ago, researchers at the University of Manchester extracted stem cells from his body, genetically inserted a functional copy of the gene responsible for the missing enzyme, and then re-injected the modified cells back into his body via a catheter.
Now, Ollie no longer relies on weekly drug infusions. His father, Ricky, said in a press release: “Ollie is doing exceptionally well since undergoing gene therapy. We have seen radical improvements, and he continues to grow physically and cognitively.”
Ollie is one of five very young children in an ongoing clinical trial of gene therapy for Hunter syndrome. Researchers, led by the Royal Manchester Children’s Hospital, hope that the one-time treatment will reduce treatment time and provide a permanent solution.
Co-clinical lead Rob Wynn said: “Gene therapy is not only safer and more effective [than a bone marrow transplant], but it enables us to use the child’s own cells, eliminating the need to find a donor.” If this approach succeeds, its principles could be adapted to treat other genetic diseases.
The Cellular Waste Problem and the IDS Enzyme
Cells constantly build, destroy, and recycle proteins. They transport excess molecules to the lysosome—which can be thought of as the “stomach of the cell”—where enzymes break them down. One of these enzymes, called iduronate-2-sulfatase (IDS), is missing in Hunter syndrome.
Enzyme replacement therapy, which Ollie and other children start with, relies on injecting the IDS enzyme into the bloodstream. This treatment improves lung and liver function and aids joint mobility. However, due to its large size, it cannot enter the brain, meaning the disease continues to attack neurological functions.
Full Replacement: Medical Procedure Details
In Ollie’s treatment, researchers used his own stem cells. The approach is based on research conducted by Brian Bigger and his colleagues. They use a viral vector, stripped of disease-causing genes, to deliver the healthy IDS gene into stem cells outside the body. The modified cells are then injected back into the patient.
Instead of using a natural copy of IDS, the team added a piece to the gene that helps the enzyme better enter the brain. Once injected, the modified stem cells multiply and release the functional enzyme throughout the body.
In late 2024, Ollie underwent a similar procedure. His doctors collected and isolated his stem cells and genetically modified them to produce the missing enzyme. While he watched cartoons, the team injected two doses of the modified cells. He recovered quickly and was discharged from the hospital a few days later.
Remarkable Recovery and Return to Childhood
Within three months of the injection, Ollie was able to stop the weekly drug infusions that had dominated his life. His speech and motor skills improved, allowing him to ride a tricycle, hang out with friends, and enjoy a normal childhood.
His mother, Jingru, told the BBC: “I want to pinch myself every time I tell people that Oliver is making his own enzymes. Every time we talk about it, I want to cry because it is so amazing.”
Next Steps and the Future of Treatment
The team is recruiting other children with Hunter syndrome into the ongoing clinical trial. Because symptoms progress so rapidly, the trial only accepts patients between 3 and 12 months of age. If the treatment succeeds, the same gene-editing approach could be used to treat other genetic diseases.
Ollie’s parents hope the treatment will be expanded to older children, including his five-year-old brother, Skyler, who also has Hunter syndrome but is currently too old for the trial. For his father, Ricky, the experimental treatment has been a success: “We are excited for Ollie’s future. Seeing the difference for Ollie before and after the transplant has made us believers. We hope the treatment will one day become available to all children at all stages of Hunter syndrome.”
Frequently Asked Questions
What is gene therapy?
It is a medical technique that uses genes to treat or prevent diseases. This can involve inserting a healthy gene to replace a missing or defective gene, or editing existing genes.
Why is this treatment groundbreaking?
Because it uses the patient’s own cells, reducing the risk of immune rejection and eliminating the need for a matched donor. It is also specifically designed to reach the brain, which current Hunter syndrome treatments fail to do.
Is this treatment a complete cure?
Treatment is still in clinical trials, but preliminary results are very promising and suggest it may provide a permanent or long-term solution by enabling the body to produce the missing enzyme itself.
What are stem cells?
They are fundamental cells with the potential to develop into many different cell types in the body. They are used in this treatment because they can multiply and spread throughout the body.
