Interleukin-4 and Interleukin-4 Receptor Alpha Gene Polymorphisms in Recurrent Aphthous Stomatitis

Background: Recurrent aphthous stomatitis (RAS) is a common oral condition with a major impact on the quality of life. The condition is thought to be due to the overexpression of T helper-1(Th1)-related cytokines. Since interleukin-4 (IL-4) and its receptor (IL-4Rα) are antagonistic to Th-1 pathways, polymorphisms in their genes may also be involved in the pathogenesis of aphthous stomatitis. Methods: Sixty-four patients diagnosed with minor RAS and 141 (age- and sex-matched) healthy controls were assessed for 3 single-nucleotide polymorphisms (SNPs) within the promoter region of the IL-4 gene (−1098G/T, −590C/T, and −33C/T), and 1 SNP in IL-4Rα gene (+1902 A/G). Results: No significant differences were detected between the patient and the control group regarding IL-4 allele frequencies. However, the patient group demonstrated a higher frequency of IL-4 −590 CC genotype and a lower rate of IL-4 −590 TC genotype. The TCT, GTT, GCT, and GTC haplotypes of the IL-4 gene (−1098, −590, −33) were significantly more frequent in the patients and the GCC, and TTT haplotypes were more common in healthy controls. No significant differences were found in IL-4Rα gene polymorphism between the 2 groups. Conclusions: Certain polymorphisms of IL4 gene could predispose individuals to RAS.