Combination Analysis of NR3C1, MTHFR and IGFBP3 Gene Polymorphisms and DNA Methylation With Steroid-induced Osteonecrosis of the Femoral Head Risk in Chinese Han Population 

Abstract

Background: Although the precise etiology of osteonecrosis of the femoral head (ONFH) has yet to be fully elucidated, it is known that nuclear receptor subfamily3, group C, member 1 (NR3C1), 5, 10-methylenetetrahydrofolate reductase (MTHFR) and insulin-like growth factor-binding protein 3 (IGFBP3) are related to the pathophysiology of steroid-induced osteonecrosis of the femoral head (SONFH). The expression of NR3C1, MTHFR and IGFBP3 are regulated by epigenetics and genetic profiles. Objective: The primary objective of this study was to investigated the association between NR3C1, MTHFR and IGFBP3 gene polymorphisms and DNA methylation status and SONFH.Methods: This case-control study included 79 patients with SONFH and 114 patients who took steroids but did not develop SONFH. We evaluated 5 single-nucleotide polymorphisms (SNPs) out of 3 genes in Chinese Han population. These SNPs were genotyped by improved multiplex ligation detection reaction (iMLDR). Methyltarget was used to test the methylation level of positive sites, the interaction between SNPs and DNA methylation level was analyzed using eQTLD technique.Results: We identified rs3110697 in the IGFBP3 gene that was potentially associated with a reduced risk of SONFH in the genotype (P=0.008; odds ratio [OR]: 0.741; 95% confidence intervals [CI]: 0.456–1.205) and in the recessive model (P=0.003; OR: NA; 95% CI: NA–NA). Furthermore, CpG sites with significant differences in methylation levels were screened as follows: IGFBP3_2-143, MTHFR_1-36, MTHFR_1-77, MTHFR_1-139, MTHFR_2-42, NR3C1_2-163, NR3C1_4-47, and the differences were statistically significant compared with the control group (p<0.05). A total of 10 pairs of linear regression tests of SNP and methylation sites were statistically significant (p<0.05).Conclusions: SONFH is a polygenic disorder in which a wide range of interactions between SNPs and DNA methylation levels may dominate the course of the disease.