Choroideremia is an eye disease that causes retinal degeneration and blindness. It is X-linked recessive which means that normally males exhibit the disease and females are carriers (on their X chromosome). In rare cases, females are also affected. Night blindness is an early symptom of choroideremia followed by loss of peripheral vision, depth perception and eventual blindness. Intermediate stages of the disease include loss of acuity and colour perception.
Choroideremia affects the cells of the retina including the retinal pigment epithelium, photoreceptors and the choroid. Research has traced the disease origins to a defective gene on the X chromosome. The gene defect prevents the body from producing functional Rab Escort Protein-1 (REP-1), an important component of normal eye function. The deficiency results in damage and ultimately death of the cells at the back of the eye.