Association of IL8 −251A/T, IL12B −1188A/C and TNF-α −238A/G polymorphisms with Tourette syndrome in a family-based association study in a Chinese Han population

Abstract

An earlier study indicated a possible relationship between Tourette syndrome (TS) and the cytokines. To explore this further, we analyzed the association of the polymorphisms, IL8 −251A/T, IL12B −1188A/C and TNF-α −238A/G, in the IL8, IL12B and TNF-α cytokine genes with TS in a Chinese Han population. A total of 108 patients diagnosed with TS and their parents were recruited for the study. The genetic contributions of the IL8 −251A/T, IL12B −1188A/C, and TNF-α −238A/G polymorphisms were evaluated using polymerase chain reaction and restriction enzyme digestion (PCR-RFLP) and haplotype relative risk (HRR) and transmission disequilibrium test (TDT) statistics. Our results revealed no significant associations between the IL8 −251A/T, IL12B −1188A/C and TNF-α −238A/G polymorphisms and TS (for IL8 −251A/T, TDT = 0.418, df = 1, P = 0.518; HRR = 2.17, X 2 = 3.000, P = 0.083, 95%CI: 0.900–5.230; for IL12B −1188A/C, TDT = 1.131, df = 1, P = 0.288; HRR = 1.27, X 2 = 0.35, P = 0.549, 95%CI: 0.580–2.790; for TNF-α −238A/G, TDT = 2.793, df = 1, P = 0.095; HRR = 0.27, X 2 = 2.90, P = 0.089, 95%CI: 0.061–1.217). This result was confirmed using haplotype-based haplotype relative risk (HHRR) which allows the two alleles in each genotype to be considered separately. Our data suggests that the IL-8 −251A/T, IL-12B −1188A/C and TNF-α −238A/G polymorphisms may not be associated with susceptibility to TS in the Chinese Han population studied. However, these results need to be replicated using larger datasets collected from different populations.