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

Vision Res. 2010 Sep 15;50(19):1989-99. doi: 10.1016/j.visres.2010.07.009. Epub 2010 Jul 16.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Color Vision Defects / genetics*
  • Color Vision Defects / pathology*
  • Cone Opsins / genetics*
  • Electroretinography
  • Female
  • Gene Deletion
  • Humans
  • Phenotype
  • Polymerase Chain Reaction
  • Retinal Cone Photoreceptor Cells / pathology*
  • Sequence Analysis, DNA


  • Cone Opsins