Deletion of the X-linked opsin gene array locus control region (LCR) results in disruption of the cone mosaic.
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.
Carroll
Joseph
J
Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI 53226, United States. jcarroll@mcw.edu
Rossi
Ethan A
EA
Porter
Jason
J
Neitz
Jay
J
Roorda
Austin
A
Williams
David R
DR
Neitz
Maureen
M
D003117:Color Vision Defects / Q000235:genetics* / Q000473:pathology*; D055358:Cone Opsins / Q000235:genetics*; D004596:Electroretinography; D005260:Female; D017353:Gene Deletion; D006801:Humans; D010641:Phenotype; D016133:Polymerase Chain Reaction; D017949:Retinal Cone Photoreceptor Cells / Q000473:pathology*; D017422:Sequence Analysis, DNA
D055358:Cone Opsins