Gene therapy for childhood sight loss: why this NHS first, matters

An eleven-year-old London girl has become the first NHS patient to receive a pioneering retinal gene therapy for a rare inherited condition that can cause severe childhood sight loss.

For optometry and ophthalmology teams, the story is not only about a world-first procedure, but about what early diagnosis, genetic testing and specialist referral can mean for families facing progressive vision loss.

Catherine L’Estrange, from North Acton, was diagnosed with Bardet Biedl Syndrome (BBS) as a baby. The ultra-rare genetic condition usually begins in childhood and can lead to near-complete loss of sight by the late teens as the retina gradually deteriorates.

She received the novel treatment at St Helier Hospital in Sutton, the first site in the world to offer the therapy for BBS10-associated retinal disease. The treatment is designed for patients whose condition is linked to mutations in the BBS10 gene, one of more than 20 genes associated with BBS.

The milestone follows the first surgery of its kind, carried out at St Helier in August 2025 on a 17-year-old patient from Canada. Catherine is now reported to be the second patient in the world to receive the therapy for BBS10.