Resident/Fellow Research Day
2004
 Phenotypic
Characterization of Blue Cone Monochromacy with Loss of the Locus Control Region
Michael A. Grassi, M.D., Benjamin R. Roos
Edwin M. Stone, M.D., Ph.D., sponsor
Purpose: To describe the phenotype of blue
cone monochromacy associated with a deletion in the locus control region.
Methods: Polymerase chain reaction was used
to characterize the molecular structure of the red pigment gene, the green
pigment gene, and the locus control region (LCR) upstream of the red gene
in a family with blue cone monochromacy. Affected individuals were examined
with the use of extensive color vision testing, funduscopy, dark adaptometry,
perimetry, and electroretinography (ERG).
Results: Analysis revealed a 16kb deletion
extending from the proximal 9kb portion of the LCR through exon 1 and
intron 1 of the red pigment gene. The remaining exons of the red gene
as well as all of the exons of the green gene were present. Affected individuals
had an interesting constellation of findings including: myopia, bilateral
macular atrophy, poor central color vision with preserved peripheral color
appreciation, and an attenuated photopic ERG response.
Conclusion: We report the association between
loss of the LCR in blue cone monochromacy and bilateral macular atrophy
with absent central color vision and preserved peripheral color vision.
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