To investigate the association of genetic polymorphisms of endothelial nitric oxide synthase (eNOS) gene with endothelial dysfunction associated osteoporosis in postmenopausal women of Punjab, India.
The study involved 456 postmenopausal women having endothelial dysfunction categorized according to women with (n = 236) and without osteoporosis (n = 220). Bone mineral density (BMD) and reactive hyperemia index (RHI) were evaluated together with six single-nucleotide polymorphisms (SNPs) within the eNOS gene (rs2070744, rs1799983, rs1800780, rs3918181, rs891512, and rs1808593).
A moderate association between RHI and BMD at femoral neck (r2 = 0.213, P = 0.002) and lumbar spine (r2 = 0.267, P < 0.001) was observed. Minor alleles C and T of SNPs rs2070744 and rs1799983 were associated with chances of osteoporosis in both co-dominant (odds ratio [OR] 2.13, P = 0.017; OR 2.77, P = 0.009) and dominant (OR 2.10, P = 0.011; OR 2.45, P = 0.007) modes, whereas minor allele A of SNP rs891512 showed marginal probability in dominant model (OR 1.68, P = 0.047). A susceptibility haplotype (CTAAAT) was observed within the eNOS gene which conferred 2.32 times higher chances of osteoporosis (OR 2.32, 95% confidence interval 1.18-4.54, P = 0.021) after adjusting for the effect of confounders. Genetic model analysis revealed that each copy of susceptibility haplotype increased the possibility of osteoporosis by a factor of 2.11 ± 0.63 (P < 0.001). RHI was significantly associated with susceptibility haplotype CTAAAT in a dose-dependent manner, whereby the severity of endothelial dysfunction increased significantly in women having two copies over women having one copy or no copy (β = 2.13, P < 0.001) of susceptibility haplotype.
A susceptibility haplotype CTAAAT within the eNOS gene is associated with double the possibility of endothelial dysfunction affiliated osteoporosis in postmenopausal women of Punjab, India.