OPSIN-LCR

This genomic region represents a locus control region (LCR) that controls cone cell-specific and mutually exclusive expression of the red and green cone pigment genes. These genes, which are present in an array on chromosome X, include one red pigment gene (opsin 1, long-wave-sensitive; OPN1LW) and one or more green pigment genes (opsin 1, medium-wave-sensitive; OPN1MW, OPN1MW2 and OPN1MW3 in the reference genome assembly). The LCR core region, which is located approximately 3.1-3.7 kb upstream of the OPN1LW gene, binds to transcription factors associated with retinal development, and it forms looping interactions with the cone pigment gene promoters. It is thought that mutually exclusive expression in individual cone cells is achieved by LCR interaction with only one gene promoter, and that genes in the cone pigment array may be preferentially selected based on distance from the LCR and/or local chromatin domain conformation. This LCR has been used to drive expression of heterologous genes in cone cells, and it has a potential use for gene therapy of achromatopsia and other retinal diseases. Mutations in this LCR result in X-linked blue cone monochromacy (BCM), and loss of the LCR results in a disrupted cone mosaic organization. [provided by RefSeq, Apr 2016]