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retinal cone dystrophy
dystrophy of cone photoreceptor cells of the retina
Epidemiology:
- type 3A is rare
Pathology:
- progressive degeneration of the cone photoreceptors with preservation of rod function
- supernormal rod responses (types 3A,3B)
- some rod involvement may be present in some cone dystrophies, especially at late stage
Genetics:
- defects in GUCA1A associated with type 3
- defects in PDE6H associated with type 3A
- defects in KCNV2 associated with type 3B
- defects in PDE6C associated with type 4 (cone dystrophy)
- defects in CACNA2D4 associated with type 4 (retinal cone dystrophy)
Clinical manifestations:
- photophobia
- night blindness (type 3A)
- loss of visual acuity, color vision & central visual field
- absence of macular lesions vs subtle depigmentation at the macula for many years
- later, more obvious areas of macular atrophy
- minimal symptoms except for slowly progressive reduction in visual acuity (type 4)
Special laboratory:
- electroretinogram
Differential diagnosis:
- cone-rod dystrophy, loss of peripheral vision also occurs
Related
cone
General
retinal disease
genetic disease of the eye
Database Correlations
OMIM correlations
References
UniProt :accession P43080