A new subset of deutan colour vision defect associated with an L/M visual pigment gene array of normal order and -71C substitution in the Japanese population

In 524 Japanese individuals with deutan colour vision defect, 76 had a normal-order pigment gene array, where the L gene is at the first position and the M gene(s) is located downstream. Of these 76 individuals, 69 had a –71A>C substitution in the M gene without any other mutation. Because the expression of L/M genes is up-regulated by thyroid hormone (T3) in human retinoblastoma WERI cells, we examined the effects of T3 on promoter activity; T3 increased the activity of the –71A promoter 2-fold, but it had no effect on the –71C promoter. Similarly, the –71C promoter was much less activated by T3 than the –71A promoter in HEK293 cells expressing thyroid hormone receptor isoform β2. Such a weak response of the –71C promoter to T3 may cause a decrease in the number of M cones and/or the density of M pigment during the differentiation of M cones. The average Rayleigh match midpoint was 18.9 ± 4.1 in 162 ordinary deuteranomaly individuals, but was 37.3 ± 9.1 in 63 deuteranomaly individuals with –71C. The –71A>C substitution was found to be specific to eastern Asia. These results suggest that there may be a new subset of deuteranomaly associated with –71C in the Japanese (and probably eastern Asian) population(s).
Source: Journal of Biochemistry - Category: Biochemistry Authors: Tags: Regular Papers Source Type: research