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Blindness study shows how gene causes middle-age sight loss

Chemical changes in the eye that can lead to blindness have been identified by scientists.

Their findings aid understanding of a genetic condition that causes sight loss for one in 3,000 people in the UK.

Scientists examined how changes in a gene known as RPGR damage eye cells to cause a disorder known as X-linked retinitis pigmentosa. The condition is incurable and affects night and peripheral vision before gradually causing blindness in middle age.

Researchers led by the University of Edinburgh took skin samples from two patients and transformed stem cells – which can change into any cell type – into light-sensing eye cells known as photoreceptors. They compared these with cells from healthy relatives of the patients.

Photoreceptors – which decay in retinitis pigmentosa patients – differed in their fundamental structure when compared with those from family members.

Follow-up studies in mice identified key molecules that interact with RPGR to maintain the structure of photoreceptors. When RPGR is flawed, the structure is compromised and photoreceptors cannot function correctly, leading to sight loss.