FIGURE 5.

Selected aspects of vitamin D metabolism designed to explore putative metabolic consequences of gene variants potentially relevant to skin pigmentation phenotype and the evolutionary model. Details are fully elaborated upon in the text, but might be particularly relevant for GC, DHCR7 and CYP11A1 gene variants. In some cases, they may have evolved to provide adaptive plasticity to differing skin phototypes i.e. DHCR7 rs11603330 and rs3794060. This secondary adaptive metabolic/genetic phenotype supports the primary pigmentation phenotype. The collective effect is a higher survival index tailored to specific environments (UVR regimes)