Genetic variants of vitamin D, estrogen α, parathyroid and collagen type I alpha receptor gene and its influence on circulating serum osteocalcin in postmenopausal osteoporosis: A cohort study

Osteocalcin is an abundant, highly conserved bone specific protein and the serum levels of OC have been used as a biochemical marker of bone turnover. The genetic variation of certain candidate genes impacts osteocalcin levels in the postmenopausal period and may predispose some women to high bone turnover. To identify the genes influencing variation in serum OC levels, we investigated the polymorphisms of Vitamin D, Estrogen α, Parathyroid and Collagen Type I alpha Receptor genes and its association with bone turnover evaluated by serum osteocalcin in postmenopausal women from south India. The polymerase chain reaction-restriction fragment length polymorphism strategy was used to detect the polymorphisms at all the four gene receptors (i.e., for VDR, ERα, PTH and COLIA1) in 300 postmenopausal women from South India. Serum osteocalcin levels were measured by immunoassay (ELISA).The serum osteocalcin levels for the Apa I polymorphisms showed varied results, in which, subjects in the control group with “GG” genotype and the osteopenic group with “TT” genotype of the ApaI polymorphism had a significantly higher serum osteocalcin concentration (p < 0.05). The BstBI-AA group in controls had a significantly higher level of serum osteocalcin, this suggests a higher state of bone turnover in the AA genotype. The outcome of this study proposes the probability of a small impact of the VDR- ApaI (GG) genotype, the VDR-TaqI (TT) genotype and the (AA) genotype of the PTH-BstBI polymorphism indicating a higher rate of bone turnover in the healthy postmenopausal women.