Associations Between Body Mass Index, WNT16 rs2908004 and Osteoporosis: Findings from Taiwan Biobank

PURPOSE: Osteoporosis is a degenerative disease that affects women and men of all races. We studied the association between body mass index (BMI), rs2908004 polymorphism of the WNT16 gene, and osteoporosis using data from Taiwan Biobank (TWB). PATIENTS AND METHODS: We analyzed data from 10,942 subjects aged 30 to 70. We defined osteoporosis based on a mean T-score of −2.5 and below in the hip. Body mass index was classified following the guidelines of the Health Promotion Administration. Imputation was carried out using the IMPUTE2 (v2.3.1) program. Multiple logistic regression was used for analysis. The odds ratios (ORs) and 95% confidence interval (CI) for osteoporosis were determined. RESULTS: In the multivariate regression model, variant rs2908004 had a significant association with osteoporosis. That is, the rs2908004-GA+AA genotype was associated with lower osteoporosis risk than the GG genotype (OR, 0.651; 95% CI = 0.544 to 0.780). Compared to normal-weight, underweight was significantly associated with a higher risk of osteoporosis (OR, 6.517; 95% CI = 4.624 to 9.186) while overweight and obesity were protective (OR, 0.176; 95% CI = 0.140 to 0.221 and 0.057; 95% CI = 0.039 to 0.083, respectively). There was an interaction between rs2908004 and BMI (p = 0.0148). Subgroup analyses (using rs2908004-GG/normal-weight as the reference group) indicated ORs of 7.66 (95% CI = 5.153 to 11.394) in the rs2908004-GG/underweight group and 3.002 (95% CI = 1.509 to 5.974) in the rs2908004-GA+AA/underweight group (95% CI = 1.509 to 5.974). Odds ratios were substantially lower in rs2908004-GG/obese, rs2908004-GG/overweight, GA+AA/normal-weight, rs2908004-GA+AA/overweight, and rs2908004-GA+AA/obese groups, respectively. CONCLUSION: According to our study, underweight was associated with an increased risk of osteoporosis irrespective of WNT16 rs2908004 genotypes, while overweight and obesity were associated with a lower risk.