Genetic association of IL-21 polymorphisms with dilated cardiomyopathy in a Han Chinese population

Background. Autoimmune abnormalities appear to be major predisposing factors for dilated cardiomyopathy (DCM). Interleukin-21 (IL-21) gene polymorphisms have been previously found to be associated with autoimmune diseases. This study aimed to assess the role of IL-21 in DCM in a Han Chinese population. Patients and methods. A total of 364 independent DCM patients and 384 unrelated healthy controls were recruited for this case-control association study. rs2055979 and rs12508721 were genotyped by PCR-RFLP.IL-21 plasma levels in samples from DCM and control individuals were evaluated by ELISA. The association between the SNPs and over-all survival (OS) was evaluated by Kaplan-Meier analysis. Hazard ratios and 95% confidence intervals (CIs) were assessed in a Cox regression analysis with adjustment for sex and age. Results. The Tallele frequencies of both SNPs were higher in DCM patients than in controls (p<0.001). The genotypic frequencies of rs2055979 G>T and rs12508721 C >T were associated with DCM in the codominant, dominant, and recessive models (p<0.05). IL-21 plasma levels in patients were higher than those of the control subjects (p=0.009). The TT genotypes of both SNPs were associated with significantly higher plasma levels (p(rs2055979)=0.03, p(rs12508721)<0.001). Kaplan-Meier analysis showed that the genotypic frequencies of both SNPs were associated with OS in the dominant and the recessive models (p<0.001). The TT genotypes of both SNPs were associated with the worst OS (p<0.001). Conclusion. Our findings suggest that the IL-21 gene plays an important role in susceptibility to DCM as well as in the clinical outcome of this ailment in the Han Chinese population.