Assignment of genes coding for brown eye colour (BEY2) and brown hair colour (HCL3) on chromosome 15q.

Brown eye colour (BEY), or total brown iris pigmentation is one of the most common phenotypes of iris colour. Data of eye colour as well as hair colour were obtained for linkage analysis through an enquiry in our family material of 832 families from Copenhagen area. By exclusion mapping with 80 markers in 120 segregating families and 290 markers in 5 segregating families, we obtained some indication of a locus BEY2 for brown eye colour on chromosome 15. For possible confirmation, we selected a total of 45 families from our DNA bank segregating for BEY. All these were tested for chromosome 15 markers in the area between D15S11 and CYP19. We found a strong indication of tight linkage with the DNA polymorphism D15S165 (Z = 24.25; theta M = F = 0.010) and with the flanking markers D15S156 (Z = 14.04; theta M = F = 0.0.029) and D15S144 (Z = 12.99; theta M = F = 0.060). BEY2 is assigned to the region 15q11-15q21 by physically localized markers. A new locus for brown hair colour (HCL3) was localized by indication of linkage to BEY2 in our 45 families segregating for BEY (Z = 9.93; theta M = F = 0.10). The gene (DN10 or P) homologous to the pink-eye-dilution gene (p) in mice could be a candidate gene for BEY2 or for HCL3.