Choroideremia is an X-linked recessive chorioretinal dystrophy that mainly affects males. Symptoms evolve from night blindness to peripheral visual field loss, eventually leading to all sight loss by middle age. The vision loss is caused by degeneration of the retinal pigment epithelium, choriocapillaris, and the photoreceptor of the eye. Carrier females are generally asymptomatic, small areas of chorioretinal atrophy can be observed with fundus examination. These changes may cause night blindness and visual field loss after the second decade.
The prevalence of choroideremia is estimated between 1:50 000-1:100 000.
Choroideremia is caused by mutations in the CHM gene, mutation spectrum includes deletions, duplications, translocations, insertions, nonsense, splice-site, frameshift and missense mutations.
Indications for genetic testing:
- Confirmation of clinical diagnosis
- Carrier testing for at-risk family members
- Genetic counseling
- Prenatal diagnosis for known familial mutation