Photopigment genes, cones, and color update: disrupting the splicing code causes a diverse array of vision disorders.

The human long- and middle-wavelength sensitive cone opsin genes exhibit an extraordinary degree of haplotype diversity that results from recombination mechanisms that have intermixed the genes. As a first step in expression, genes-including the protein coding exons and intervening introns-are transcribed. Next, transcripts are spliced to remove the introns and join the exons to generate a mature message that codes for the protein. Important information necessary for splicing is contained within exons, and is overlaid by the protein code. Intermixing the long- and middle-wavelength sensitive cone opsin genes has disrupted the splicing code, leading to exclusion of some exons from the mature message and is associated with several vision disorders including nearsightedness, cone dystrophy, and color vision deficiencies.