Association study involving polymorphisms in IL-6, IL-1RA, and CTLA4 genes and rheumatic heart disease in New Zealand population of Maori and Pacific ancestry

Introduction: Rheumatic fever (RF) incidence among New Zealand (NZ) individuals of Polynesian (Maori and Pacific) ancestry remains among the highest in the world. Polymorphisms in the IL-6, IL1RN, and CTLA4 genes have been associated with RF, and their products are modulated by new medications. Confirmation of these previous associations could help guide clinical approaches. We aimed to test IL-6, IL-1RA (IL1RN), and CTLA4 functional SNPs in 204 rheumatic heart disease (RHD) patients and 116 controls of Maori and Pacific ancestry. Material and method: Self-reported ancestry of the eight great-grandparents defined ancestry of participants. Severity of carditis was classified according to the 2012 World Heart Federation guideline for the echocardiographic diagnosis of RHD. The IL-6 promoter rs1800797, IL1RN rs447713 and CTLA4 rs3087243 SNP5 were genotyped by Taciman. Correlations were assessed by logistic regression analysis adjusting for gender and ancestry. Results: The IL-6 rs1800797 variant was significantly associated with RHD with carriers of the GG genotype 6.09 (CI 1.23; 30.23) times more likely to develop RHD than the carriers of the AA genotype (P = 0.027). No significant associations with RHD were found for the IL1RN rs447713 and CTLA4 rs3087243 SNP5. Patients carrying the G allele (GG plus AG genotype) for the IL1RN rs447713 SNP had 2.36 times (CI 1.00; 5.56) more severe carditis than those without this allele (the AA genotype) (P = 0.049). Conclusion: The IL-6 promoter rs1800797 (-597G/A) SNP may influence susceptibility to RHD of people of Maori and Pacific ancestry living in NZ. The IL1RN rs447713 SNP may influence the severity of carditis in this population. (C) 2016 Elsevier Ltd. All rights reserved.