Gene therapy approval brings a price tag that most families cannot reach
For one Swansea family, the approval of the first gene therapy for Sanfilippo syndrome should have been a medical milestone. Instead, it landed like a cruel invoice. Tate McDaid, a five-year-old boy with Sanfilippo syndrome type A, now faces a treatment cost of £2.95 million for a one-time therapy approved in the United States, a figure far beyond the reach of almost any family in Britain.
The emotional collision is stark. A therapy designed to slow a relentlessly progressive neurodegenerative disorder has arrived just as Tate’s mother, Tammy McDaid, is trying to hold back the pace of decline before her son loses more function. In a condition where every month matters, access and timing have become inseparable from the biology of the disease.
Sanfilippo syndrome strips away skills in early childhood
Sanfilippo syndrome, also called mucopolysaccharidosis type III or MPS III, is often described as childhood dementia because it causes progressive neurodegeneration in children. The disorder is rare, with just over 100 children affected in the UK, although a charity supporting families says about 140 UK children live with the condition.
The disease gradually erodes abilities that many families once took for granted: walking, eating, communication, and movement. Tate has not spoken, and his mother says mobility is everything to him. He is already showing signs of cognitive decline. In a condition like this, worsening is not abstract; it becomes visible in how a child moves through a room, how easily he feeds, and how long learned skills can be retained.
The syndrome can accelerate after age five. For Tate, who is turning six, that detail is not just a clinical description. It is the edge of the window in which treatment may still preserve function.
The first approved therapy changes the conversation, not the prognosis
In September, the first gene therapy for children with this condition was approved in the United States. The treatment, called FAYUVI, is intended to delay disease onset and help children remain active for longer. The approval matters because Sanfilippo syndrome type A has no cure, and the natural course of the illness is relentlessly progressive.
Gene therapy is biologically appealing in this setting because the disorder arises from a missing or defective gene product. Replacing or correcting that pathway aims to address the root cause rather than only treating symptoms. For a neurodegenerative disease, the logic is powerful: intervene early enough, and there may still be neurons and function worth preserving. Intervene too late, and the opportunity narrows as loss accumulates.
Tammy McDaid spent months hoping for approval. When it arrived, relief lasted only briefly. The next day brought the US price: $3.95 million, equal to £2.95 million, for a single treatment course.
The number is not theoretical. It is the difference between an approved therapy and an inaccessible one.
Families outside the United States face an uncertain path to treatment
Tammy contacted Ultragenyx, the company behind the therapy, to ask how families outside the US could possibly cover the cost. The company said it could not provide a single estimate for the total cost of care for an international patient because those costs would depend on the child’s medical needs and the treating institution.
That answer leaves a wide gap between regulatory approval and real-world access. Families in the UK do not operate within the American insurance system, and the treatment is not yet available in Britain. Health officials in Wales are speaking with counterparts in the US to see what access pathways might exist for Tate. Staff at Noah’s Ark Children’s Hospital in Cardiff are also involved in those discussions.
Tammy has raised more than £160,000 so far. It is an impressive sum by any ordinary fundraising measure, but it covers only about 5% of the estimated cost. The arithmetic is brutal: hundreds of thousands raised, millions still required, and time continuing to pass.
The bedside stakes are measured in lost movement, not abstract endpoints
In rare pediatric neurodegenerative disease, treatment value cannot be judged only by the headline price or even by regulatory approval. The real question is whether the therapy can slow the loss of mobility, cognition, and daily function before the disease passes a point where benefit shrinks. For Tate’s family, mobility is the priority because it is tied directly to his quality of life and independence.
Tammy describes her son as “the happiest little man,” blissfully unaware of what is happening to him. That innocence makes the urgency more painful, not less. She says if a millionaire offered the money tomorrow, they would travel to the US straight away.
The timing is unforgiving. She believes the treatment will work less well as Tate gets older and loses more ability. Her fear is not only about what the disease has already taken, but about what it could take before the family secures access.
Regulatory success has outrun global access
Ultragenyx said it is pursuing a global regulatory strategy and described FDA approval as an important first step toward bringing the treatment to families around the world. The company also acknowledged the urgency felt by families affected by Sanfilippo syndrome type A and said some may consider travelling to the US for gene therapy. It advised families to work with their child’s healthcare provider to understand possible access routes before assuming that cross-border travel is the only option.
For now, the therapy exists in the narrow space between scientific progress and financial impossibility. The disease biology is clear enough: a rare inherited defect drives a rapidly progressive neurological decline. The treatment logic is also clear: replace the missing function before the decline becomes irreversible. What remains unresolved is access for children like Tate who live outside the US and do not have a payment structure capable of absorbing a multimillion-pound therapy.
As Tate approaches another birthday, the family’s fight has become a race against neurological loss, not just a search for funding. The drug is approved, but the path to it is still under construction.