Contributed by Walter F. Bodmer, October 25, 2017 (sent for review May 18, 2017; reviewed by Marcus W. Feldman and Benjamin M. Neale)
The human face is extraordinarily variable, and the extreme similarity of the faces of identical twins indicates that most of this variability is genetically determined. We have devised an approach to increase the chance of identifying specific large genetic effects on particular facial features, by choosing features with high heritability and selecting individuals with relatively extreme facial phenotypes for comparison with a control population. This has yielded three specific and replicated genetic variants, two for features of facial profiles, and one for the region around the eyes. Further application of these methods 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.
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 (PCs) 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 1,832 unique volunteers from the well-characterized People of the British Isles study and 1,567 unique twin images from the TwinsUK cohort, together with genetic data for 500,000 SNPs, we have identified three specific genetic variants with notable effects on facial profiles and eyes.
↵1D.J.M.C. and B.W. contributed equally to this work.
↵2Deceased May 12, 2017.
Author contributions: W.F.B. conceived the project; B.W. and T.D. organized collection of PoBI data; D.J.M.C., K.H., D.M., A.B., and W.F.B. assisted in data collection; P.H., A.N., and T.D.S. collected TwinsUK data; W.P.K. and W.J.C. conducted image registration analysis under supervision of J.K.; D.J.M.C. analyzed registered image data and genetic data under supervision of W.F.B.; D.J.M.C. and W.F.B. wrote the manuscript, with W.P.K. and W.J.C. contributing additional technical material; and B.W. and W.F.B. supervised the project.
Reviewers: M.W.F., Stanford University; and B.M.N., Broad Institute.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1708207114/-/DCSupplemental.
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