Statistical genetic analysis of plasma levels of vitamin D: familial study

The present study attempted to evaluate the relative importance of familial /genetic factors in interindividual variation of plasma concentrations of v itamin D (calcidiol). Ninety-five nuclear pedigrees (187 males and 168 fema les, aged 18-91 and 18-86 years old respectively), from the Chuvasha Autono my, Russia, were assessed for calcidiol and sex hormones. Age-adjusted 25-h ydroxy-vitamin D (25OHD) measures showed very high pair-wise correlations b etween all members of families, which suggest that there may be a genetic f actor transmitted within the families. To test this assumption, complex seg regation analysis of non-adjusted 25OHD data was undertaken, in which genot ype-sex specific dependence of the trait on age was incorporated. The analy sis showed that some 44% of the 250HD variance was attributable to all gene tic and non-genetic factors incorporated into the model. About 22% of the v ariation was accounted for by a putative major gene effect.