Abstract

Genes encoding cone pigments sensitive to middle-to-long wavelengths lie in a head-to-tail tandem array on the X-chromosome. Although two X-encoded genes, one for long-wavelength-sensitive pigments and one for middle-wavelength-sensitive pigments, are sufficient to serve trichromatic color vision, most people have more than two such genes. The arrangement, location, and degree of homology of the pigment genes promote recombination within the tandem arrays. Such recombination events produce pigment-gene complements that differ in the number and sequences of individual genes and in the interrelationships between genes. The accumulation of recombination-generated changes over the span of evolutionary time has culminated in a large number of X-encoded photopigment gene complements in the human population. It is, thus, not surprising that there are widespread variations in human color vision.

© 1990 Optical Society of America