Novel KCNV2 mutations in cone dystrophy with supernormal rod electroretinogram

Am J Ophthalmol. 2008 Jun;145(6):1099-106. doi: 10.1016/j.ajo.2008.02.004. Epub 2008 Apr 9.


Purpose: To describe patients with cone dystrophy and supernormal rod electroretinogram (ERG) and search for mutations in the recently described KCNV2 gene.

Design: Clinical and molecular study.

Methods: Patients from three families originating from France, Morocco, and Algeria had standard ophthalmologic examination and color vision analysis, Goldmann perimetry, International Society for Clinical Electrophysiology of Vision (ISCEV) protocol in accordance with ERG testing, autofluorescence evaluation, and optical coherence tomography 3 scanning. The two coding exons of KCNV2 were polymerase chain reaction amplified and sequenced.

Results: All patients had the characteristic features of supernormal, delayed rod ERG responses at the highest levels of stimulation and markedly reduced cone responses. In the French family, two affected sisters were compound heterozygotes for the recurrent c.1381G>A (Gly461Arg) mutation and for a novel c.442G>T (Glu148Stop) mutation. In the Moroccan family, affected members were homozygotes for the novel c.1404delC mutation (His468fsX503) and in the Algerian family, the proband was homozygote for the novel c.1001delC mutation (Ala334fsX453). In the three families, parents were unaffected heterozygote carriers. None of the mutations were present in 50 control chromosomes.

Conclusions: The three novel truncative mutations are likely to be null mutations leading to loss of function, with no difference in the phenotype presentation. Amino acid changes are found exclusively in the N-terminal fragment of the protein and in the P-loop, indicating the importance of those regions for the function of the KCNV2 protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Color Vision Defects / diagnosis
  • Color Vision Defects / genetics*
  • Color Vision Defects / physiopathology
  • Consanguinity
  • Dark Adaptation
  • Electroretinography
  • Female
  • Genotype
  • Humans
  • Male
  • Middle Aged
  • Mutation*
  • Pedigree
  • Photic Stimulation
  • Polymerase Chain Reaction
  • Potassium Channels, Voltage-Gated / genetics*
  • Retinal Cone Photoreceptor Cells / physiopathology*
  • Retinal Degeneration / diagnosis
  • Retinal Degeneration / genetics*
  • Retinal Degeneration / physiopathology
  • Retinal Rod Photoreceptor Cells / physiology*
  • Tomography, Optical Coherence


  • KCNV2 protein, human
  • Potassium Channels, Voltage-Gated