Single-nucleotide polymorphisms (SNPs) in genes encoding for susceptibility factors may influence gene expression, protein function, and disease predisposition.[15,16] More and more studies suggested that SNPs in interleukins genes, such as IL4 (−590T/C, −1098T/G), IL6 (−174G/C), IL10 (−592C/A, −819C/T, and −1082G/A), and IL18 (−137G/C, −607C/A), were correlated with development OLP or the severity of OLP.[17–20] However, these results were mixed, inconclusive, and even inconsistent. The gene discussed is IL18; the disease is oral lichen planus.