This report describes general characteristics of the group of diseases classified as cone-rod dystrophy (CRD or CORD). Cone-rod dystrophy is a genetically heterogeneous disorder with many causative genes and mapped loci. The table below includes links to more detailed reports for subtypes that have been investigated using fly models.
A number of human genes associated with retinal disease are implicated in multiple related diseases, including retinitis pigmentosa, cone-rod dystrophy, and forms of macular degeneration. See human disease model reports for 'retinal disease, PROM1-related' (FBhh0000571) and 'retinal disease, CRX-related' (FBhh0000567).
[updated Jun. 2017 by FlyBase; FBrf0222196]
Cone-rod dystrophy (CRD or CORD) is among a group of diseases described as hereditary cone disorders (Roosing, et al., 2014; pubmed:24857951).
In contrast to typical retinitis pigmentosa (RP), which results from the primary loss in rod photoreceptors, later followed by secondary loss in cone photoreceptors, cone-rod dystrophies (CRDs) exhibit the opposite sequence of events. The clinical course of CRDs is generally more severe and rapid than that of RPs, leading to earlier legal blindness and disability. (Hamel, 2007; pubmed:17270046).
Cone-rod dystrophy characteristically leads to early impairment of vision. An initial loss of color vision and of visual acuity is followed by nyctalopia (night blindness) and loss of peripheral visual fields. In extreme cases, these progressive symptoms are accompanied by widespread, advancing retinal pigmentation and chorioretinal atrophy of the central and peripheral retina (Moore, 1992; pubmed:1583653). [from MIM:120970; 2017.06.30]
It is likely that highly deleterious mutations in genes that otherwise cause retinitis pigmentosa or macular dystrophy may also lead to cone-rod dystrophy (Hamel, 2007; pubmed:17270046).
There are more than 30 types of cone-rod dystrophy, which are distinguished by their genetic cause and their pattern of inheritance: autosomal recessive, autosomal dominant, and X-linked. [Genetics Home Reference, cone-rod dystrophy; 2017.06.30]
