Cone-rod dystrophies (CRDs)
are a group of inherited eye disorders that affect both the cone and rod cells of the retina (photosenstitive receptor cells). In contrast to rod-cone dystrophies, individuals experience deterioration of the cone cells more severely than the rod cells. Initial signs and symptoms typically include decreased visual acuity when looking straight ahead (central vision loss); loss of color perception; and an abnormal sensitivity to light (photophobia). These signs are usually followed by progressive loss of peripheral vision and night blindness. Most cases occur due to mutations in any one of several genes, and CRDs can be inherited as autosomal recessive, autosomal dominant, X-linked or mitochondrial (maternally-inherited) traits. CRDs are usually non-syndromic, but they may also be part of several syndromes. Currently, there is no therapy that stops progression of the disease or restores vision; management aims at slowing the process, treating complications and helping individuals cope with the social and psychological impact of blindness. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.