Genetic analysis of interleukin 18 gene polymorphisms in alopecia areata

Abstract

Background: Alopecia areata (AA), which appears as nonscarring hair shedding on any hair-bearing area, is a common organ-specific autoimmune condition. Cytokines have important roles in the development of AA. Interleukin (IL) 18 is a significant proinflammatory cytokine that was found higher in the patients with AA. We aimed to investigate whether the IL-18 (rs187238 and rs1946518) single nucleotide polymorphisms (SNPs) may be associated with AA and/or clinical outcome of patients with AA in Turkish population. Methods: Genotyping of rs187238 and rs1946518 SNPs were detected using sequence-specific primer-polymerase chain reaction (SSP-PCR) method in 200 patients with AA and 200 control subjects. Results: The genotype distribution of rs1946518 (−607C>A) SNP was found to be statistically significantly different among patients with AA and controls (P =.0008). Distribution of CC+CA genotypes and frequency of −607/allele C of rs1946518 SNP were higher in patients with AA (P =.001, P =.001, respectively). The genotype distribution of rs187238 (−137G>C) SNP was found to be statistically significantly different among patients with AA and control subjects (P =.0014). Distribution of GG genotype and frequency of −137/allele G of rs187238 SNP were higher in patients with AA (P =.0003, P =.001, respectively). Conclusion: The rs1946518 (−607C>A) and rs187238 (−137G>C) polymorphisms were found associated with alopecia areata disease. The study suggests that IL-18 rs187238 and rs1946518 SNPs may be the cause of the AA susceptibility.