Analysis of polymorphism of bone metabolism genes and evaluation of the risk of osteopenia in cosmonauts

The densitometry of cosmonauts after long-term missions shows a reduction of bone mineral density (BMD). On average, the postflight BMD remains within the normal range and the broad variability of individual BMD values is sometimes regarded as local osteopenia. Individual reactions are classified by the similarity of amount and rate of BMD loss. Today, the analysis of functionally significant polymorphism of bone metabolism genes is the most effective tool for diagnosing susceptibility to osteopenia and osteoporosis. The study was aimed at analyzing the polymorphism for genes of vitamin D (VDR) and calcitonin (CALCR) receptors, as well as the collagen-1 alpha1 chain (Col1a1) in candidate cosmonauts and cosmonauts returned from 5- to 7-month missions. The results of the analysis showed that, in the majority of cosmonauts, a rapid BMD loss correlated with the TT genotype for the VDR gene, but not with Tt and tt genotypes, and was associated with the carriage of an incomplete s-allele in the Col1a1 gene. However, in several cases, high BMD loss rates were personified with the carriers of the VDR gene alleles (in homozygous and heterozygote states, tt and Tt) and the heterozygote for the Col1a1 gene (Ss).