Assignment of genes coding for brown eye colour (BEY2) and brown hair colour (HCL3) on chromosome 15q.
ABSTRACT 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.
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ABSTRACT: Original Article Objective: We determined the prevalence and pattern of human color traits in young adults in Eastern Nigeria and assessed whether there were gender differences and inter-relationships in the prevalence of these color traits. Methods: Three hundred young adults aged 18-40 yrs, participated in the study. The iris color was categorized into four; light brown, dark brown, dark, and blue-grey colors. The skin color was categorized into three colors; fair, brown and black. Three hair colors-black, brown and blond were identified amongst the study population. Results: The present data indicated that dark brown iris color (69%), brown skin color (50.3%) and black hair color (56.7%) were the most prevalent color traits in the study population. Data indicated gender differences (P<0.01 or P<0.001) in the distribution of the three color traits. In both genders, data indicated significant interactions (P<0.05; P<0.01; P<0.001) amongst the three color traits, suggesting that these color traits are highly inter-correlated. Conclusion: The most prevalent human color traits among young adults in the Eastern Nigeria were dark brown iris, brown skin and black hair colors. There were gender differences and inter-correlations amongst the three human color traits.
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ABSTRACT: The role of epistatic effects in the determination of complex traits is often underlined but its significance in the prediction of pigmentation phenotypes has not been evaluated so far. The prediction of pigmentation from genetic data can be useful in forensic science to describe the physical appearance of an unknown offender, victim, or missing person who cannot be identified via conventional DNA profiling. Available forensic DNA prediction systems enable the reliable prediction of several eye and hair colour categories. However, there is still space for improvement. Here we verified the association of 38 candidate DNA polymorphisms from 13 genes and explored the extent to which interactions between them may be involved in human pigmentation and their impact on forensic DNA prediction in particular. The model-building set included 718 Polish samples and the model-verification set included 307 independent Polish samples and additional 72 samples from Japan. In total, 29 significant SNP-SNP interactions were found with 5 of them showing an effect on phenotype prediction. For predicting green eye colour, interactions between HERC2 rs12913832 and OCA2 rs1800407 as well as TYRP1 rs1408799 raised the prediction accuracy expressed by AUC from 0.667 to 0.697 and increased the prediction sensitivity by >3%. Interaction between MC1R ‘R’ variants and VDR rs731236 increased the sensitivity for light skin by >1% and by almost 3% for dark skin colour prediction. Interactions between VDR rs1544410 and TYR rs1042602 as well as between MC1R ‘R’ variants and HERC2 rs12913832 provided an increase in red/non-red hair prediction accuracy from an AUC of 0.902 to 0.930. Our results thus underline epistasis as a common phenomenon in human pigmentation genetics and demonstrate that considering SNP-SNP interactions in forensic DNA phenotyping has little impact on eye, hair and skin colour prediction.Forensic Science International: Genetics 07/2014; DOI:10.1016/j.fsigen.2014.01.012 · 3.20 Impact Factor
- Piel 02/2011; 26(2):66-79. DOI:10.1016/j.piel.2010.09.020