An 11-year-old girl has become the first British patient to receive pioneering gene therapy for a rare condition that typically causes blindness by the early 20s. Catherine L'Estrange, from North Acton, west London, was diagnosed with Bardet-Biedl syndrome (BBS) as a baby and underwent the procedure at St Helier Hospital in March.
Treatment details
Surgeons removed the jelly inside Catherine's eye and injected healthy copies of the BBS10 gene into her retina. The gene therapy, developed by biotechnology company MeiraGTx, had previously been performed on only one other person in the world – a 17-year-old girl from Canada who received the treatment at St Helier in August last year. Since Catherine's procedure, one other younger child with BBS has also been treated.
BBS affects around one in 100,000 births in the UK. The condition is caused by a gene mutation and leads to gradual vision loss as cells in the retina die. BBS can also cause kidney problems, learning difficulties, obesity, and sometimes extra fingers or toes.
Patient and family response
Catherine said: "If this treatment works, it will help me to carry on seeing things around me, and most of all I will be able to carry on reading books, which is one of my favourite things to do." Her father, Reverend Timothy L'Estrange, said: "Our whole family has been so grateful for the opportunity to save Catherine's vision - it will be absolutely life-changing for her to retain any vision at all."
Reverend L'Estrange noted that most children with BBS are not diagnosed until primary school, but Catherine was diagnosed at just a few weeks old. He said: "Our policy was to develop her independence and resilience as much as possible, ready for the inevitable loss of her sight, which began with her becoming night-blind, then colour-blind, and continued with her losing her peripheral vision. We were told that possible gene therapy was many, many years away, and was likely to arrive after Catherine had entirely lost her sight - so we were surprised and delighted when we learned this treatment had become available."
Medical team and outlook
Neruban Kumaran, consultant eye surgeon at Epsom and St Helier University Hospitals NHS Trust, said: "By giving a healthy copy of the gene, it helps save those cells, and the hope is to either stabilise or improve vision. One of the things that causes a lot of anxiety [for parents] is the worry that these children lose vision and possibly lose their independence. There's no other treatment for this, and so the opportunity to protect vision or improve vision, or give them hope that they won't lose their vision and they can maintain that independence, it really means a lot."
So far only one of Catherine's eyes has been treated. Patients undergo sight tests after the therapy, including reading from a chart and identifying colour shades. Mr Kumaran said some patients have reported better vision in dim light, and feedback has been positive, though full results will take years. He said: "There is a hope that it may improve vision slightly, but it's difficult to say. It's not going to leave someone with perfect vision. But the hope is to stabilise and/or improve vision. Only time will tell."
The team at St Helier worked with experts at Great Ormond Street and Moorfields Eye Hospital to identify eligible young children with the specific BBS10 gene mutation. Mat Shaw, chief executive of St George's, Epsom and St Helier Hospitals Group, said: "As a father, I can't imagine how it feels to watch your child slowly go blind, and I'm so proud that our teams are offering hope to these children and their families, which aims to stop childhood blindness in its tracks."
