[Association of bone mineral density with gene polymorphisms and environmental factors in Chinese postmenopausal women]

Abstract

Objective: To investigate the relationship between bone mineral density (BMD) and polymorphisms of the eatrogen receptor (ER) and vitamin D receptor (VDR) in relation to some environmental factors.

Methods: Ninety postmenopausal Chinese rural women of Han population, aged 45 to 65, were voluntarily enrolled in this study. We conducted BMD measurement of the lumber spine and hip by dual energy X-ray absorptiometry (DXEA) and performed a questionnaire survey of diet intake and outside activity. The polymorphisms of ER gene and VDR gene were determined using polymerase chain reaction restriction fragment length polymorphism ( PCR-RFLP).

Results: There is no significant influence of ER Px haplotype on BMD in Chinese women. VDR Bsm I polymorphisms was associated with BMD at the lumbar spine and the BMD in the Bb genotype was lower than in the bb genotype (P < 0.05), but the significant difference was weakened after adjusting for confounding factors such as age height weight activity diet and menopause age. Women with the ER Px haplotype and VDR B allele genotype had lowest BMD at lumber (P < 0.05), but the difference of BMD became not significant after adjusting for confounding factors such as age height weight activity diet and menopause age. Diet calcium, protein, carbohydrate and energy simply related to BMD. Stepwise multiple regression analysis showed that age and body weight were strong predictor of BMD in postmenopausal women. Other significant predictors were menopausal age and carbohydrate at lumber spine and menopausal age at femur neck.

Conclusion: BMD was not associated with ER genotype but with VDR Bsm I polymorphism. Environmental factors influence the relationship between gene polymorphism and BMD.