Bodmer, W. F. | bioRxiv Science

bioRxiv2018

Genetic patterning in Central Eurasia: population history and pigmentation

Central-western Asia has often been underrepresented in population genetic studies, but it is important for the clarification of the peopling of Eurasia and the relationship between its western and eastern extremities. We genotyped individuals from over 40 population groups, mostly central Eurasian, for mitochondrial HVR1, CCR5del32 and five functional MC1R variants (p.Val60Leu, p.Val92Met, p.Arg151Cys, p.Arg160Trp, p.Arg163Gln), and collected published genotype data for comparison. Mitochondrial profiles confirm both the higher heterozygosity in Central Asia than in surrounding areas, and the broadly northern European distribution of CCR5del32. The MC1R variants profile alone is a good determinant of the longitudinal position of a population group, and combined FST values divide Eurasia into seven broad geographic divisions. We can conclude that Central Asia shares genetic features with both eastern and western Eurasia, compatible with both a scenario where the former acted as a source for the latter twos genetic diversity, or one where Central Asia is a hybrid zone where eastern and western peoples met. Furthermore, the overall high FST values for functional MC1R variants combined with presumed selection pressures on skin pigmentation in low-UV areas lead us to conclude that different variants were selected for in east and west Eurasia, an example of convergent evolution.

genetics↗

bioRxiv2017

The genetics of the human face: identification of large effect single gene variants

In order to discover specific variants with relatively large effects on the human face we have devised an approach to identifying facial features with high heritability. This is based on using twin data to estimate the additive genetic value of each point on a face, as provided by a 3D camera system. In addition, we have used the ethnic difference between East Asian and European faces as a further source of face genetic variation. We use principal components analysis to provide a fine definition of the surface features of human faces around the eyes and of the profile, and chose upper and lower 10% extremes of the most heritable PCs for looking for genetic associations. Using this strategy for the analysis of 3D images of 1832 unique volunteers from the well characterised People of the British Isles study [1, 2] and 1567 unique twin images from the TwinsUK cohort (www.twinsuk.ac.uk), together with genetic data for 500,000 SNPs, we have identified three specific genetic variants with notable effects on facial profiles and eyes.\n\nSignificance statementThe human face is extraordinarily variable and the extreme similarity of the faces of identical twins indicates that most of this variability is genetically determined. This level of genetic variability has probably arisen through natural selection, for example, for recognition of membership of a group or as a consequence of differential mate selection with respect to facial features. We have devised an approach to identifying specific genetic effects on particular facial features. This should enable the understanding, eventually at the molecular level, of the nature of this extraordinary genetic variability, which is such an important feature of our everyday human interactions.\n\nAuthor ContributionsWFB conceived the project. BW and TD organised collection of PoBI data and KH, DJMC, DM, AB and WFB assisted in data collection. TDS, PH and AN collected TwinsUK data. WPK and WJC conducted image registration analysis under supervision of JK. DJMC analysed registered image data and genetic data under supervision of WFB. WFB and DJMC wrote the manuscript, with WJC and WPK contributing additional technical material. WFB and BW supervised the project.

genetics↗