Association between an intronic apolipoprotein E polymorphism and bone mineral density in Singaporean Chinese females

Introduction: Apolipoprotein E (ApoE) is implicated in the pathogenesis of osteoporosis.

Objective: To investigate possible association of the non-classical APOE gene +113C/G (rs440446) intron 1 enhancer polymorphism with bone mineral density (BMD) in a homogeneous Chinese population in Singapore.

Methods: A total of 655 volunteers, males and females, aged between 31 and 72 years, from the public participated. BMD was measured using dual-energy X-ray absorptiometry and APOE +113C/G (rs440446) genotypes were determined by Sequenom MassARRAY system. To adjust for potential confounders, anthropometric, demographic, and lifestyle determinants were obtained, and serum lipids and E(2) were measured.

Results: The +113C/G (rs440446) polymorphism within the APOE gene was associated with BMD in Chinese Singaporean females only. Females with the heterozygous CG genotype were significantly associated with reduced total, lumbar spine, and femoral neck of hip BMD, after multilevel adjustment of confounders. The association was stronger in the spine than in the hip. When females were stratified according to WHO classification for osteoporosis, those with CG and GG genotypes had increased risk (OR 3.50 and 2.22, respectively) of developing osteopenia/osteoporosis in the lumbar spine. Serum lipids did not explain the influence of APOE +113 C/G (rs440446) on BMD.

Conclusion: This study demonstrated an association between APOE +113C/G (rs440446) polymorphism with measures of BMD in Singaporean Chinese females.