Overview: a breakthrough in ADA-SCID treatment
A Portlaoise boy’s participation in a landmark medical study has yielded life-changing results, offering new hope for children born with the rare immune condition ADA-SCID. The nine-year-old, Andy Cash, was diagnosed with the life-threatening disorder just weeks after birth, and his family faced a long, difficult journey before a novel gene therapy trial offered a potential cure.
What is ADA-SCID and why is it so serious?
Adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) is caused by mutations in a gene that produces an enzyme essential for a functional immune system. Without this enzyme, affected children have virtually no immune protection, making even routine activities like attending school dangerous due to the risk of serious infections. If left untreated, the condition can be fatal in the early years of life.
The challenge of finding a donor and the turn to gene therapy
Traditionally, treatment might involve enzyme-replacement therapy, regular antibody infusions, and preventive antibiotics until a bone marrow donor could be found. For Andy, a donor was never identified, and his family navigated a grueling treatment landscape while seeking any chance for a cure. Mary Cash, Andy’s mother, recalls the moment the experimental option emerged: “the clinical team looked for a bone marrow transplant donor but one couldn’t be found globally. Family members and his three older siblings were tested but none of them were a match, unfortunately.”
That search led to a multicountry gene therapy trial conducted by researchers at Great Ormond Street Hospital (GOSH) in London and collaborators worldwide. The approach removes patients’ own cells, modifies them in the lab to correct the genetic defect, and reintroduces them to rebuild a healthy immune system.
The trial and its long-term follow-up
The study enrolled 62 children and young people across the United Kingdom and the United States, with follow-up extending up to a decade. Results revealed that about 95 percent of treated participants were cured, a striking success rate for a population with previously limited options. Notably, children who retained a functional immune system could receive routine vaccinations—an achievement that was impossible before this gene therapy.
Andy’s journey to treatment and what life looks like now
Getting to the trial was itself an arduous process for Andy and his family due to his compromised immunity. Mary describes a period of isolation at hospital followed by long trips to England: “We were isolated in hospital for a few months and then at home, before taking the ferry to England and travelled through the night to GOSH to make it as safely as possible for Andy.” After a two-month stay at GOSH following the treatment, the family returned to County Laois when Andy was five months old. Today, Andy is described by his mother as a bundle of energy who has embraced sports and social life. “He’s like a mini celebrity, wherever he goes everybody loves him, he’s very charming!”
What this means for Andy’s future and for others
The success of this gene therapy trial carries implications beyond ADA-SCID. Experts believe the approach could inform treatments for other genetic conditions that rely on replacing defective cells. Professor Claire Booth, the trial’s lead, emphasizes the broader impact: “It is very reassuring for other conditions treated using the same techniques, showing that it works in the long term and is safe.”
Looking ahead
The positive outcomes provide renewed optimism for families facing ADA-SCID and related immune disorders. The trial’s results encourage ongoing research into gene therapies and their long-term safety, sparking conversations about accessibility, monitoring, and follow-up care for patients who might benefit in the coming years.
About the story and sources
This report draws on updates from the Great Ormond Street Hospital trial team, families affected by ADA-SCID, and researchers leading the international study. While Andy’s story is individual, the data reflect a larger success in a field that has long sought a durable, safer alternative to donor-dependent treatments.
