KCNV2 retinopathy, historically referred to as cone dystrophy with supernormal rod electroretinogram, is a rare autosomal recessive inherited retinal dystrophy caused by biallelic pathogenic variants in the KCNV2 gene. The condition typically presents in childhood with reduced visual acuity, photophobia, impaired color vision, and progressive central visual loss, while night vision may be relatively preserved in early stages.
A defining feature of the disorder is a characteristic full-field electroretinography profile. Scotopic responses may show disproportionately large b-wave amplitudes at higher stimulus intensities, whereas photopic responses are markedly delayed and reduced. This electrophysiological pattern is considered highly suggestive of KCNV2-associated retinopathy and may be present even when funduscopic or structural retinal changes are minimal.
The KCNV2 gene encodes a modulatory subunit of voltage-gated potassium channels expressed in photoreceptors. Pathogenic variants are thought to disrupt normal photoreceptor signaling, resulting in combined cone dysfunction and abnormal rod responses. Additional descriptive electrophysiological and genetic case documentation has been made available through open research repositories.
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↑Wu H, Cowing JA, Michaelides M, et al. Mutations in the gene KCNV2 encoding a voltage-gated potassium channel subunit cause cone dystrophy with supernormal rod electroretinogram in humans. American Journal of Human Genetics. 2006;79(3):574–579. doi:10.1086/507568.
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