Choroideremia

Choroideremia (CHM), also known as tapetochoroidal dystrophy or progressive choroidal atrophy, is a rare inherited retinal dystrophy characterized by progressive degeneration of the choroid, retinal pigment epithelium (RPE), and photoreceptors. The disease primarily affects the eyes and leads to progressive vision loss. It is caused by mutations in the CHM gene (Xq21.2), which encodes Rab escort protein 1 (REP-1), a protein essential for intracellular vesicular trafficking. The earliest symptom is typically night blindness (nyctalopia), which usually begins in childhood or early adolescence. This is followed by progressive constriction of the visual fields (tunnel vision) due to loss of peripheral vision, as the degeneration of the choroid and RPE spreads from the periphery toward the center of the retina. Central vision may be preserved until the fourth or fifth decade of life, but most affected males eventually develop severe visual impairment or complete blindness by late adulthood. Fundoscopic examination reveals characteristic scalloped areas of chorioretinal atrophy with visible underlying sclera, progressing from the periphery inward. Female carriers typically have a milder phenotype, often showing patchy areas of chorioretinal changes on fundoscopy but usually retaining functional vision throughout life, though some carriers may experience mild symptoms such as night blindness. There is currently no approved cure for choroideremia, though management includes regular ophthalmologic monitoring, low-vision aids, and genetic counseling. Gene therapy has emerged as a promising therapeutic approach, with several clinical trials investigating subretinal delivery of adeno-associated virus (AAV) vectors carrying a functional copy of the CHM gene. Voretigene neparvovec-related approaches specific to CHM are under active investigation, and early trial results have shown potential for stabilizing or modestly improving visual function in treated eyes. Supportive measures including UV-protective eyewear and vitamin supplementation are sometimes recommended, though their efficacy is not firmly established.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Choroideremia