Project: Research project

Project Details


Red or green color vision deficiency ("color blindness") is one of the most
common genetic variants in the population, affecting up to 10% of males.
Recent studies about the molecular genetics of color vision deficiency,
suggest that this arises from deletion of the visual pigment genes on the X
chromosome or from the presence of fusion genes which code for visual
pigments having anomalous wavelengths of absorption. Coupled with the
finding that copy number of the green visual pigment gene is polymorphic in
the population, these observations would suggest that the visual pigment
loci on the X chromosome are a target for recurrent unequal recombination.
To study the molecular basis of this genetic variation, we propose to
examine the organization of the visual pigment loci in males with normal
color vision (trichromats) as well as those who have color vision
deficiency. Color vision will be rigorously tested by use of an analytical
anomaloscope. Gene mapping studies will be performed by conventional
Southern blotting and by field inversion gel electrophoresis. Genes that
have been quantified by densitometry of autoradiograms, will have the copy
number confirmed by measuring the size of the NotI restriction fragment
that contains the entire visual pigment gene complex. The intergenic
regions between red and green and between green and green visual pigment
genes will be cloned and mapped to determine where they have diverged. We
will use these DNA flanking sequences to map the genomes of the other
subjects with normal color vision and with gene copy numbers of R:G 1:1 and
1:2 to establish the degree of genetic variability that may exist in these
individuals and to identify the sites of recombination that gave rise to
the gene copy number polymorphisms. We will establish the gene organization
of individuals with visual pigment deficiency and will map potential sites
of recombination in individuals with color vision deficiency. These sites
will be sequenced to determine whether they have common structural features
among themselves or with other "hot spots" of recombination previously
identified in the genome. We anticipate that these studies will yield
insight into how unequal recombination contributes to the development of
genetic defects.
Effective start/end date6/1/905/31/96


  • Genetics
  • Molecular Biology


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