Bone mineral density and five prominent candidate genes in Chinese men: associations, interaction effects and their implications.

OBJECTIVES

Osteoporosis constitutes a serious health problem in old people. Bone mineral density (BMD) is determined by multiple genetic and environmental factors. The genetic control of BMD and osteoporosis is better understood in women, but much less in men. The present study evaluated the relationship of COL1A2, BGP, IL-6, AHSG and PTH genes defined by MspI, HindIII, BsrBI, SacI and BstBI restriction enzymes, respectively, with BMD in Chinese males.

METHODS

A total of 258 unrelated healthy Chinese men aged 50-80 years were recruited. BMD at spine (L1-4) and femoral neck were measured by a Hologic 2000+ densitometer and adjusted by significant covariates of age, height and weight. All the subjects were genotyped at the upper five polymorphic sites by PCR-RFLP procedure.

RESULTS

We revealed significant association of the AHSG gene with the spine BMD (P = 0.006), even after adjusting for multiple testing in our study. Carriers of 1*1 and 2*2 genotypes of AHSG gene had, respectively, approximately 5.1 and 8.1% higher spine BMD than those of 1*2 genotype. For the other four genes, no evidence of association was found (P > 0.10). No significant evidence of gene-by-gene interaction was found by two-way factorial ANOVA on the BMD variation.

CONCLUSIONS

The results suggest that the AHSG gene is associated with the spine BMD in Chinese men. The present study represents the first effort to simultaneously investigate the effects of single gene locus as well as gene-by-gene interactions of multiple genes on BMD variation in Chinese men.