Severity of color vision defects: electroretinographic (ERG), molecular and behavioral studies

Earlier research on phenotype/genotype relationships in color vision has shown imperfect predictability of color matching from the photopigment spectral sensitivities inferred from molecular genetic analysis. We previously observed that not all of the genes of the X-chromosome linked photopigment ge...

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Bibliographic Details
Published in:Vision research (Oxford) 1998-11, Vol.38 (21), p.3377-3385
Main Authors: Crognale, M.A, Teller, D.Y, Motulsky, A.G, Deeb, S.S
Format: Article
Language:English
Subjects:
Adaptation, Ocular - physiology
Adolescent
Adult
Biological and medical sciences
Color vision
Color Vision Defects - genetics
Color Vision Defects - physiopathology
Electroretinography
Exons
Flicker ERG
Gene Expression
Genetics
Humans
Male
Medical sciences
Middle Aged
Molecular Biology
Ophthalmology
Photopigments
Psychophysics
Rayleigh matches
Retinal Pigments - genetics
Rod Opsins - genetics
Spectrophotometry
Vision disorders
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Summary:Earlier research on phenotype/genotype relationships in color vision has shown imperfect predictability of color matching from the photopigment spectral sensitivities inferred from molecular genetic analysis. We previously observed that not all of the genes of the X-chromosome linked photopigment gene locus are expressed in the retina. Since sequence analysis of DNA does not necessarily reveal which of the genes are expressed into photopigments, we used ERG spectral sensitivities and adaptation measurements to assess expressed photopigment complement. Many deuteranomalous subjects had L, M, and L–M hybrid genes. The ERG results showed that M pigment is not present in measurable quantities in deutan subjects. Using these results to determine gene expression improved the correlations between inferred pigment separation and color matching. Furthermore, we found a subject who had normal L and M genes and normal proximal promoter sequences, yet he had a single photopigment (M) by ERG and tested as a protanope. These results demonstrate the utility of ERG measurements in studies of molecular genetics of color vision deficiencies, and further support the conclusion that not all genes are expressed in color deficient subjects. In particular, deuteranomaly requires a presently unknown mechanism of selective expression which excludes normal M genes and allows expression of L–M hybrid genes in one cone type, and the normal L in another.
ISSN:0042-6989
1878-5646
DOI:10.1016/S0042-6989(97)00425-2