Choroideremia

Choroideremia is a rare, X-linked recessive inherited eye disease that causes progressive degeneration of the retina and underlying choroid, affecting roughly one in fifty thousand males. It results from loss-of-function mutations in the CHM gene, which encodes Rab escort protein 1, a protein needed for normal function of the light-sensitive cells and supporting tissue of the retina. Symptoms usually begin in childhood with night blindness, followed by gradual loss of peripheral vision that produces tunnel vision, and eventually decline of central vision later in life; the rate of progression varies between affected individuals. The disease is coded H31.2 in the ICD-10. It was first described in 1872 by the Austrian ophthalmologist Ludwig Mauthner, who initially believed it was a developmental disorder involving absence of the choroid rather than a degenerative one. The responsible CHM gene was identified and cloned more than a century later, in 1990, by the geneticist Frans P. M. Cremers, opening the way for later research into gene therapy approaches.