While the length of the nose is often a focus for beauty standards—some cultures preferring a long nose, and others a short—there is also nasal width. Nasal width refers to the maximum width of the nose, and it is measured as the distance between the left and right nostrils. There is a great deal of evidence that genes influence facial appearance. This is perhaps most apparent when we look at our own families since we are more likely to share facial features in common with our close relatives than with unrelated individuals.
Figure. The distance measured as nasal width in this study.
To date, only a few studies have explicitly tested for associations between aspects of normal human facial morphology and common genetic variants. Among these, two genome-wide association studies (GWAS) have been carried out on healthy individuals of European ancestry using 3D facial imaging and a combination of traditional and more advanced morphometric methods to derive phenotypes. A handful of intriguing genome-wide significant signals were reported between these two studies, although they were largely non-overlapping. Although these GWASs and candidate gene studies have detected a handful of plausible genes associated with variation in facial features, it is clear that these efforts are just scratching the surface.
Therefore, to discover additional candidate genes associated with face shape researchers performed GWA analyses on a set of 20 craniofacial measurements commonly used in clinical assessment.In this study, 3118 healthy individuals of European ancestry belonging to two independent samples from Pittsburgh and Denver in the United States participated. In both samples, subjects were excluded if they had a personal history of racial trauma, plastic surgery, implant, and birth defects. Participants’ 3D facial surfaces were captured using digital stereophotogrammetry, a standard imaging method to measure the surface contours of the human body. In total, seven associations in five traits showed statistical significance. The mean nasal width in the Pittsburgh and the Denver sample was 33.6mm (SE=0.07) and 29.55 mm (SE=0.09) respectively. One SNP at 20p11.22 near the Paired Box 1 (PAX1) gene showed a significant influence on nasal width. Study found that mutations in the PAX1 gene cause specific nasal features such as a sunken nasal root and excessive narrowing. There were also suggestive significant associations between several SNPs at chromosome 20 with nasal width in the meta-analysis of the two cohorts.
These results provide further evidence that common variants in regions that scientists know influence facial structure contribute to normal variation in human facial features. However, researchers mentioned that it is still not clear which variant might be functional and which genes they regulate. Thus, references to implicated genes should always be treated with appropriate caution. Read more about the study here:
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