Genetic association of the P-glycoprotein gene ABCB1 polymorphisms with the risk for steroid-induced osteonecrosis of the femoral head in Chinese population.

Steroid administration, which is commonly performed for the treatment of autoimmune inflammatory diseases, cancers or organ transplantation, has been a leading cause of nontraumatic osteonecrosis of the femoral head (ONFH). Single nucleotide polymorphisms (SNPs) of the adenosine triphosphate-binding cassette B1 (ABCB1) gene have been demonstrated to be related to steroid-induced ONFH in small sample sizes of Japanese kidney failure and Chinese systemic lupus erythematosus patients. However, there are obvious controversial results in the relationship of ABCB1 gene polymorphisms with steroid-induced ONFH. The aim of this study was to validate the genetic association of ABCB1 polymorphisms with the risk for steroid-induced ONFH in a large cohort of Chinese population. A case-control study was conducted, which included 94 and 106 unrelated patients after steroid administration recruited from 14 provinces in China, respectively. Two SNPs (rs1045642 and rs2032582) within ABCB1 were genotyped using Sequenom MassARRAY system. Multivariate analyses based on clinical information were performed to determine the associations between the SNPs and risk of steroid-induced ONFH. rs1045642 SNP was significantly associated with steroid-induced ONFH group in codominant (P=0.02), recessive (P=0.006) and overdominant (P=0.03) models. However, there were no differences found in genotype frequencies of rs2032582 SNP between controls and patients with steroid-induced ONFH (all P>0.05). These findings suggested that rs1045642 SNP of ABCB1 may be associated with the risk of steroid-induced ONFH. Thus, it is useful to analyze this polymorphism for identifying high-risk individuals before the administration of steroids.