Elsevier

Vision Research

Volume 50, Issue 19, 15 September 2010, Pages 1989-1999
Vision Research

Deletion of the X-linked opsin gene array locus control region (LCR) results in disruption of the cone mosaic

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Abstract

Blue cone monochromacy (BCM) is an X-linked condition in which long- (L) and middle- (M) wavelength-sensitive cone function is absent. Due to the X-linked nature of the condition, female carriers are spared from a full manifestation of the associated defects but can show visual symptoms, including abnormal cone electroretinograms. Here we imaged the cone mosaic in four females carrying an L/M array with deletion of the locus control region, resulting in an absence of L/M opsin gene expression (effectively acting as a cone opsin knockout). On average, they had cone mosaics with reduced density and disrupted organization compared to normal trichromats. This suggests that the absence of opsin in a subset of cones results in their early degeneration, with X-inactivation the likely mechanism underlying phenotypic variability in BCM carriers.

Abbreviations

BCM
blue cone monochromacy
ERG
electroretinogram
AO
adaptive optics
AOSLO
adaptive optics scanning laser ophthalmoscope
LCR
locus control region

Keywords

Adaptive optics
Blue cone monochromacy
Color vision
Cones
Opsin
Photopigment

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1

These authors contributed equally to this work.