Gene Therapy · uk
Rare Blindness Gene Therapy Used in Children for the First Time, BBS10 Therapy Enters Human Safety Observation Period
A UK medical team has administered subretinal gene therapy to one eye in three children and adolescents in an attempt to restore a normal BBS10 gene; this first-in-human use remains a limited, physician-led treatment program and cannot yet be regarded as a successful clinical trial or an approved therapy.
For children progressively losing their vision due to a genetic defect, treatment often must begin before large numbers of retinal cells die. A UK medical team has now used a gene replacement therapy targeting BBS10 mutations in humans for the first time. Three children and adolescents have received the treatment, marking an early step forward for this extremely rare inherited retinal degeneration.
The therapy, developed by MeiraGTx, uses an adeno-associated viral vector to carry a normal BBS10 gene. Physicians first perform a vitrectomy and then inject the vector beneath the retina in one eye, with the aim of providing surviving retinal cells with a functional copy of the gene. Treating only one eye also allows the team to limit safety risks to a smaller scope and compare changes between the two eyes during follow-up.
The first recipient was a 17-year-old Canadian adolescent who completed treatment at St Helier Hospital in the UK in August 2025. Catherine L’Estrange, age 11, subsequently became the second recipient worldwide and the first in the UK. Eligible patients were identified with assistance from specialist teams at Great Ormond Street Hospital, Moorfields Eye Hospital, and other institutions. The program’s preclinical foundation includes mouse studies conducted by MeiraGTx and the Drack laboratory at the University of Iowa in the US.
The primary question in this human use is not how much vision can improve, but whether the surgery and gene vector have acceptable safety and feasibility. Patients are expected to undergo at least 12 months of follow-up, during which researchers will collect data on ocular responses and visual function. There is currently insufficient human evidence to show that the therapy can halt degeneration, restore vision, or provide lasting effects.
Background
BBS10 mutations can cause Bardet-Biedl syndrome. In addition to retinal degeneration, patients may experience obesity, kidney abnormalities, and other systemic problems. This therapy targets only BBS10-related eye disease. It cannot treat other manifestations of the syndrome and is not suitable for retinal diseases caused by different genetic defects.
The treatment is supplied under the UK Medicines and Healthcare products Regulatory Agency’s “Specials Licence” mechanism through a physician-led program for a small number of preselected patients. It is not a formal clinical trial and does not mean that regulators have determined it to be safe and effective. Whether it can progress from a small number of cases to more comprehensive clinical development will still depend on follow-up results, reproducible efficacy signals, and whether the risks associated with the surgery and vector can be clearly defined.