The association of eNOS gene polymorphism with avascular necrosis of femoral head.

OBJECTIVES Necrosis of femoral head is a severe pathological state with multiple etiologies. This study investigated the association of the 27-bp repeat polymorphism in intron 4 and G894T polymorphism in exon 7 of the endothelial nitric oxide synthase (eNOS) gene with the pathogenesis of avascular necrosis of femoral head (ANFH). METHODS A total of 125 non-traumatic ANFH patients and 126 healthy controls were recruited for this study. The 27-bp repeat polymorphisms in intron 4 were analyzed by polymerase chain reaction (PCR) and sequencing. The G894T polymorphisms in exon 7 were analyzed by PCR- restriction fragment length polymorphism (PCR-RFLP) analysis. RESULTS All alleles were observed in non-traumatic ANFH patients and control subjects. Both ANFH patients and idiopathic subgroup of ANFH patients showed higher frequency of the 4a/b genotype than controls (p = 0.001 and p = 0.020, respectively). Significantly higher frequency of G/T genotype was observed in ANFH patients and idiopathic subgroup of ANFH patients compared to controls (p = 0.009 and p = 0.035, respectively). CONCLUSION eNOS gene polymorphisms may be a risk factor for ANFH. The 27-bp repeat polymorphism in intron 4, G894T polymorphism in exon 7, and subsequently reduced eNOS activity may be involved in the etiology of idiopathic ANFH.