June 2013
Volume 54, Issue 15
ARVO Annual Meeting Abstract  |   June 2013
Frequency of atypical genotypes associated with normal and defective color vision
Author Affiliations & Notes
  • Candice Davidoff
    Ophthalmology, University of Washington, Seattle, WA
  • Jay Neitz
    Ophthalmology, University of Washington, Seattle, WA
  • Maureen Neitz
    Ophthalmology, University of Washington, Seattle, WA
  • Footnotes
    Commercial Relationships Candice Davidoff, None; Jay Neitz, Alcon (F), Alcon (P); Maureen Neitz, Genzyme (F), Alcon (F), Alcon (P)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 3022. doi:
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      Candice Davidoff, Jay Neitz, Maureen Neitz; Frequency of atypical genotypes associated with normal and defective color vision. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3022.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: The majority of red-green color vision deficiencies result from gene rearrangements that cause the loss of normal L or M opsin expression. This can be due to deletion of an L or M gene or insertion of an extra L gene between the normal L and M genes, displacing the M gene to a non-expressed position. Thus, characterizing the number of L and M genes is a good predictor of the presence and type of congenital red-green color vision defects. However, two atypical types of mutations, missense mutations and extra L opsin genes downstream of the expressed positions, would result in misdiagnoses based on L and M gene stoichiometry. This study aims to estimate the frequency of these types of mutations in the population.

Methods: For 803 males unselected for color vision deficiencies, PCR was performed to selectively amplify L or M opsin genes. From these products exons 3 and 4 were sequenced. The number and type of opsin genes on the X-chromosome were determined by SNP analysis using Sequenom's MassARRAY system. For samples found to have extra L genes, long range PCR was performed to amplify the most downstream gene and verify whether it encoded an L or M opsin. For samples with missense mutations, parts of the last gene were sequenced to determine if the mutation was in a gene in an expressed position.

Results: 3 missense mutations were identified in L opsin genes: R151T, V171L and V232L. 8 mutations were found in M opsin genes: six C203R, one R163I and one synonymous mutation. No C203R mutation was observed in any L opsin gene. 74 samples were found to have extra L genes. Of these 25 were confirmed to have the extra L in an expressed position, 20 were confirmed to have L genes at the end of the array and thus are likely to have normal color vision, and 29 had arrays too long to determine the position of the extra L gene.

Conclusions: C203R mutations are unlikely to cause protan defects. Missense mutations that may cause protan defects were present in 0.37% of the sample and those that may cause deutan defects were detected in 1%. 9% of men in this sample have more than one L gene. Of those, at least a quarter had the genetic basis for normal color vision despite the presence of an extra L gene. 3.1% of men could be confirmed to have an L gene in the second position and are presumed to have deuteranomaly and another 3.6% may be deuteranomalous depending on the location of the extra L gene(s) in arrays with > 3 genes.

Keywords: 471 color vision • 539 genetics  

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