Objective: To investigate the association of Apa I polymorphism in vitamin D receptor (VDR) gene with bone mass in men.
Methods: The VDR Apa I genotype was determined by PCR-restriction fragment length polymorphism (RFLP) in 388 unrelated healthy men aged 46-80 years of Han nationality in Shanghai city. Bone mineral density (BMD) and bone mineral content (BMC) at lumber spine 1-4 (L1-4) and at any sites of proximal femur including to femoral neck (Neck), trochanter (Troch) and Ward's striangle (Ward's) were measured by duel-energy X-ray absorptiometry.
Results: Frequencies distribution of VDR Apa I genotype were aa for 48.1%, Aa for 44.2% and AA 7.7%. The allele frequencies of Apa I polymorphism were in Hardy-Weinberg equilibrium. No significant association was found between Apa I genotype and BMD or BMC in group of all population or in subgroup of men below 60 years. In men above 60 years, the significant association was found between VDR Apa I genotype and BMD or BMC at L1-4, Neck and Ward's (P < 0.05, P < 0.01) and compared with Aa and aa genotype, AA genotype had significantly higher mean BMD and BMC at L1-4, Neck and Ward's (P < 0.05, P < 0.01). But Apa I genotype is not associated with BMD and BMC at Troch.
Conclusions: Apa I polymorphism is associated with bone mass in men above 60 years, and AA genotype has higher bone mass. Apa I polymorphism in VDR gene possibly influence loss of trabecular and cortical bone mass in old men.