Genetic Determination of Head-Size-Related Anthropometric Traits in an Ethnically Homogeneous Sample of 373 Indian Pedigrees of West Bengal

Abstract

The substantial involvement of genetic factors in the determination of head-size and head-shape traits has been firmly established. However, there has been a lack of agreement on a number of specific issues concerning the pattern of inheritance of craniofacial features. In this study we examined some of these issues in a large, ethnically homogeneous sample of Indian pedigrees. The data included 1,263 individuals belonging to 373 nuclear families. Eleven raw head-size traits and two synthetic phenotypes, interpreted as horizontal and vertical head-size components (HOC and VEC, respectively), were used in the analysis. To establish the pattern of inheritance of head traits, we carried out univariate and bivariate analyses. Maximum heritability estimates ranged from 0.41 to 0.83 for the studied head-size phenotypes. The portion of the total residual variance attributable to putative additive genetic factors was 68.3% and 70.3% for HOC and VEC, respectively, and common familial factor effects were found to be nonsignificant. The extent of genetic influences did not differ significantly with respect to sex or between HOC and VEC. The results of bivariate variance decomposition analysis strongly suggest the existence of common genetic factors simultaneously affecting HOC and VEC; 41.8% of the two traits' total residual variance was attributable to the effect of these common genetic factors.

Heritability of face shape in twins: a preliminary study using 3D stereophotogrammetry and geometric morphometrics

“…Principal shape components associated with the degree of horizontal separation between the eyes, the length, breadth and projection of the nose, and the height and projection of the upper lip all demonstrated high heritability. These findings are largely supported by more traditional anthropometric studies that utilize standard linear distances to quantify facial surface structures [18-20,22-35]. There is also substantial overlap between the results of the present study and those of prior 3D facial surface studies on twin pairs.…”

“…Several prior studies report the highest heritability estimates for vertically oriented facial measures [6,9-11,24,54], although there is considerable disagreement on this point [7,14,33-35]. The current findings present a slightly more complex picture.…”

“…While the majority of craniofacial heritability studies are limited to measures of skeletal structure, most often derived from radiographs, a smaller number of studies have focused solely on external soft-tissue features [17-35]. These studies typically use traditional anthropometric methods (i.e., direct measurement with calipers) to quantify the head and face, reporting similar heritability estimates for these surface traits as for the underlying skull.…”

Heritabilities of Facial Measurements and Their Latent Factors in Korean Families

“…In recent years, most studies based on this concept assessed 2 common factors: horizontal components (HOCs) and vertical components (VECs). Several investigations found that the genetic effect was estimated differently between 2 factors [8, 10, 14, 18, 19]. In these studies, however, the extraction of common latent variables in facial complex measurements was only limited to HOCs and VECs.…”