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In This Issue

Facial similarities tend to run in families, and genetically identical twins raised together or apart exhibit striking facial resemblance, suggesting strong genetic control of human facial features. Yet studies have largely failed to identify single gene variants with large effects on facial features. Daniel Crouch et. al (pp. E676–E685) used an analysis of images of identical and nonidentical twins to weight each point on the face by the extent to which it is genetically influenced. Next, the authors used the weights in a principal components analysis of 3D camera images of faces from 1,832 volunteers from the People of the British Isles project, 1,567 participants in the TwinsUK cohort, and 33 East Asian volunteers. Focusing on the upper and lower 10% of extremes of three composite facial phenotypes, which were derived from facial profiles and surface features of the region around the eyes, the authors identified two genetic variants tied to facial profiles in females and one genetic variant tied to surface features around the eyes in both males and females. One variant exhibited linkage with a gene implicated in Usher syndrome, which is marked by vision, hearing, and balance defects, whereas another was located in a gene involved in regulating steroid biosynthesis. The third variant was located in a zinc transporter with a potential role in mucolipidosis type IV, a condition occasionally accompanied by facial dysmorphia, particularly around the eyelids. According to the authors, identification of gene variants with large and specific effects on facial features paves the way toward unraveling the molecular mechanisms by which genes shape the extraordinary variability in human facial appearance. — P.N.