title: Novel KCNV2 mutations in cone dystrophy with supernormal rod electroretinogram.
abstract: OBJECTIVE
  To describe patients with cone dystrophy and supernormal rod electroretinogram (ERG) and search for mutations in the recently described KCNV2 gene.
  
  
  METHODS
  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.
authors.affiliation: Genetics of Sensory Diseases and Department of Ophthalmology, Hospital of Montpellier, Montpellier, France.
authors.forename: Safouane
authors.initials: S
authors.lastname: Ben Salah
authors.forename: Satomi
authors.initials: S
authors.lastname: Kamei
authors.forename: Audrey
authors.initials: A
authors.lastname: Sénéćhal
authors.forename: Séverine
authors.initials: S
authors.lastname: Lopez
authors.forename: Christian
authors.initials: C
authors.lastname: Bazalgette
authors.forename: Cécile
authors.initials: C
authors.lastname: Bazalgette
authors.forename: Claudie Malrieu
authors.initials: CM
authors.lastname: Eliaou
authors.forename: Xavier
authors.initials: X
authors.lastname: Zanlonghi
authors.forename: Christian P
authors.initials: CP
authors.lastname: Hamel
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003117:Color Vision Defects / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology; D003241:Consanguinity; D003623:Dark Adaptation; D004596:Electroretinography; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D010775:Photic Stimulation; D016133:Polymerase Chain Reaction; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics*; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology*; D012162:Retinal Degeneration / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D041623:Tomography, Optical Coherence
chemical_list: C489610:KCNV2 protein, human; D024642:Potassium Channels, Voltage-Gated