Genetics of human body size and shape: evidence for an oligogenic control of adiposity

In a previous study by the authors in each of the pedigree samples from Kir ghizstan, Turkmenia and Chuvashia, four principal factors supposedly contro lled by four non-overlapping gene subsets were found. About 90% of total va riation of adiposity as assessed by 22 measurements of skinfolds, circumfer ences and indices were covered by these factors. This study provides result s of segregation analysis of each of these four factors. By the usual trans mission probability tests, major gene (MG) control was accepted in all 12 a nalyses-four traits in three populations. Some of the most parsimonious MG models included non-MG effects, such as correlation of residuals between sp ouses, between parent and offspring and between sibs. The Kirghizian sample s showed a significant assortative mating effect as measured by the correla tion between genotypic values at putative MG in spouses. The proportion of the trait variance attributable to the MG effect varied from 0.296 (factor F4 in the Chuvashia sample) to 0.596 (the same factor in the Kirghizian sam ple). It is assumed that four independent large-effect genes can be recogni zed in the genetic control of adiposity determining, respectively, individu al predisposition to accumulate subcutaneous fat, its distribution between the body trunk and extremities, predisposition to accumulate inner fat and its distribution between the upper and lower body parts. In each population , unification of the four most parsimonious MG models forms oligogenic mode ls explaining from 0.364 (Chuvashia) to 0.540 (Kirghizstan) of total adipos ity.