Quantitative genetic study of head size related phenotypes in ethnically homogeneous Chuvasha pedigrees

Background: It is well established that genetic factors contribute significantly to the determination of head size and shape traits variability. However, the controversies in views and findings with respect to the more specific aspects of this issue have not yet been resolved. Aim: The primary objective of the study was to examine the patterns of the intergenerational familial transmission of 12 head size related traits in a large ethnically homogeneous sample of Chuvasha pedigrees. Subjects and methods: The research was carried out on 1406 individuals belonging to 357 nuclear and more complex families. Univariate and bivariate family-based analyses were performed to establish the pattern of head traits inheritance. Results: Maximum heritability estimates ranged from 0.52 to 0.72 for traits adjusted for significant covariates. No significant sex differences were observed with respect to the genetic determination of the studied traits. Bivariate analysis of horizontal and vertical head size components suggested the existence of common genetic and environmental factors that explained 33.0% and 23.2% of the total variance of the adjusted traits, respectively. Conclusions: A significant genetic component is involved in inter-individual variation and covariation of various studied craniofacial traits.