The OPN1SW gene (on chromosome 7) and the OPN1LW and OPN1MW genes (on the X chromosome) encode the three opsin pigments found in cone cells of the retina. Mutations in either the OPN1LW or OPN1MW gene can cause red-green color vision defects. Blue-yellow color vision defects are more likely to be the result of mutations in the OPN1SW gene.GHR
Note that in addition to point mutations, larger chromosomal rearrangements as well as insertions & deletions involving opsin-encoding genes may lead to colorblindness.
SNPs known to be be associated with colorblindness include: