The IL18 gene and Hashimoto thyroiditis in children

Interleukin 18 (IL18) stimulates interferon-γ production in Th1 cells which are prominent in the thyroid of Hashimoto thyroiditis (HT). We investigated the association between the IL18 gene and HT. There were 116 children with HT and 1272 controls. rs187238 and rs1946518 in the promoter region of the IL18 gene were genotyped. Differences in genotype, allele, carrier, and haplotype distributions between patients and controls were compared. A Pc value <0.05 was considered significant. The frequency of the C/G genotype of rs187238 was significantly higher in patients and conferred a risk of HT (OR, 1.96; 95% CI, 1.30–2.95; Pc, 0.0021). So did the frequencies of allele C (OR, 1.73; 95% CI, 1.22–2.44; Pc, 0.0035) and carrier C (OR, 1.96; 95% CI, 1.31–2.92; Pc, 0.0017), however the frequency of the G/G genotype was significantly lower in patients than in controls (OR, 0.51; 95% CI, 0.34–0.76; Pc, 0.0034). There was no association between HT and rs1946518. The CT haplotype was significantly more frequent in patients than in controls and conferred a risk of HT (OR, 1.76; 95% CI, 1.24–2.49; Pc, 0.0049). We concluded that the IL18 gene was associated with HT in children. The rs187238C allele and CT haplotype conferred a risk of HT.