Association of eNOS polymorphisms with susceptibility to osteonecrosis of the femur head : A meta-analysis.

OBJECTIVE: The aim of the present study was to determine whether polymorphisms of the endothelial nitric oxide synthase (eNOS) gene are associated with susceptibility to osteonecrosis of the femoral head (ONFH).

METHODS: We conducted a meta-analysis to assess the association between the 4b/a, G894T, and T786C polymorphisms of eNOS and the susceptibility to ONFH.

RESULTS: A total of five studies, which included 566 cases and 833 controls, were included in the meta-analysis. Meta-analysis revealed a significant association between allele a of the 4b/a polymorphism and ONFH in all study subjects (odds ratio, OR 3.237; 95 % confidence interval, CI 2.036-5.148; P = 6.9 × 10(-7)); stratification by ethnicity indicated an association between this allele and ONFH in Caucasians and Asians (OR 2.985; 95 % CI 1.592-5.597; P = 0.001 and OR 3.567; 95 % CI 1.793-7.095; P = 2.9 × 10(-4), respectively). Meta-analysis stratified by ONFH type showed a significant association between allele a of the 4b/a polymorphism and idiopathic and secondary ONFH (OR 3.411; 95 % CI 2.049-5.679; P = 2.4 × 10(-6) and OR 3.163; 95 % CI 1.781-5.619, P = 8.6 × 10 (-5), respectively). However, the meta-analysis did not show any allelic association between the G894T and T786C polymorphisms and ONFH (OR 1.718; 95 % CI 0.796-3.707; P = 0.168 and OR 1.027; 95 % CI 0.191-5.517; P = 0.976, respectively).

CONCLUSION: Our meta-analysis of published studies shows that the 4b/a polymorphism is associated with the development of idiopathic and secondary ONFH in Caucasians and Asians.