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Novel KCNV2 mutations in cone dystrophy with supernormal rod electroretinogram
Safouane Ben Salah1, Satomi Kamei, Audrey Sénéćhal
1Genetics of Sensory Diseases and Department of Ophthalmology, Hospital of Montpellier, Montpellier, France.
American Journal of Ophthalmology
|April 11, 2008
Summary
This study identifies novel KCNV2 gene mutations in patients with cone dystrophy and supernormal rod electroretinograms (ERG). These mutations likely cause loss of function, impacting vision.
Area of Science:
- Ophthalmology
- Genetics
- Molecular Biology
Background:
- Cone dystrophy is an inherited retinal disorder affecting cone photoreceptors, leading to visual impairment.
- Supernormal rod electroretinogram (ERG) responses, characterized by delayed and enhanced rod activity, are observed in some retinal dystrophies.
- The KCNV2 gene, encoding a potassium channel subunit, has been recently implicated in retinal disorders.
Purpose of the Study:
- To characterize patients presenting with cone dystrophy and supernormal rod ERG.
- To investigate the role of the KCNV2 gene by searching for mutations in affected individuals.
Main Methods:
- Clinical and molecular genetic analysis of three families with cone dystrophy and supernormal rod ERG.
- Comprehensive ophthalmologic examinations including color vision, perimetry, ERG, autofluorescence, and OCT.
- Sequencing of the coding exons of the KCNV2 gene to identify mutations.
Main Results:
- All patients exhibited reduced cone ERG responses and characteristic supernormal rod ERG.
- Three novel KCNV2 mutations were identified: a compound heterozygous mutation (Gly461Arg and Glu148Stop) in the French family, a homozygous deletion (His468fsX503) in the Moroccan family, and a homozygous deletion (Ala334fsX453) in the Algerian family.
- Parents were unaffected carriers, and none of the mutations were found in 50 control chromosomes.
Conclusions:
- The identified KCNV2 mutations are likely null mutations causing loss of function.
- These mutations do not appear to alter the phenotype presentation of cone dystrophy with supernormal rod ERG.
- Mutations in the N-terminal fragment and P-loop of the KCNV2 protein highlight the functional importance of these regions.
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