Thursday, September 25, 2008

Genes and facial features   posted by Razib @ 9/25/2008 02:49:00 PM

Dienekes posted a bunch of abstracts from a meeting of the American Society of Human Genetics. This one jumped out at me:
Seven selection-nominated candidate genes (COL11A1, LMNA, FGFR1, FGFR2, TRPS, BRAF, FLNA) known to be involved in Mendelian craniofacial dysmorphologies and to have high allele frequency differences between West African and European populations were tested for admixture linkage to normal facial feature traits. The sample consists of 254 subjects (n=131 African Americans, n=123 Brazilians) of West African and European genetic ancestry. Each individual was genotyped at 176 ancestry informative markers (AIMs), which allowed for proportional estimation of genetic ancestry from four parental populations and adjustments for admixture stratification.

3D images of faces were acquired using the 3dMDface imaging system. 3D coordinate data were collected from 22 landmarks placed on each image using the 3dMDPatient software. The 231 possible pairwise landmark distances were scaled to the geometric mean and then analyzed using Euclidean Distance Matrix Analysis.

We used both ANOVA and ADMIXMAP to control for admixture stratification and to test for associations between the 231 pairwise landmark distances and 183 AIMs, using sex, height and BMI as covariates. We used a four-population model (West African, European, East Asian, and Native American).

There is a strong concordance between the ANOVA and ADMIXMAP results. Many landmark distances, particularly on the mouth and nose, were significantly associated with genetic ancestry. Additionally, three of the candidate genes show no effects on pairwise landmark distances while four show distinct patterns of association. For example, FGFR2 is associated primarily with the length of the face. These results represent the first identification of the first genes affecting normal variation in facial features.

A definite new twist possible on DNA forensics.