Lack of association between interleukin 13, interleukin 4 receptor alpha, andMS4A2 gene polymorphisms and asthma in adult Saudis

Objectives: Several genes, including interleukin-13 (IL13), MS4A2, and IL 4 receptor alpha (IL4Rα), have been shown to associate with the inflammatory process in asthma. We investigated the possible association between asthma and five single-nucleotide polymorphisms (SNPs) in the IL13, IL4Rα, and MS4A2 gene in comparison with the level of the IL-13 protein in the Saudi asthmatics and controls. Subjects and Methods: The study group included 50 adult asthmatic patients and 50 normal healthy controls. Blood was extracted, and DNA was prepared. Genotyping was performed on DNA using direct sequencing for four SNPs (rs20541, rs1800925, rs1801275, and rs569108), and real-time polymerase chain reaction allelic discrimination to study rs1805010 polymorphism. Levels of IL-13 were measured in plasma using (enzyme-linked immunosorbent. Genotype and allele frequencies were calculated for each SNP. Results: The results showed that GG genotype of rs1801275 in the IL4Rα gene was more common in the asthmatic patients compared to the control group, though the results did not show any statistical significance (P < 0.08). Conclusions: No significant association was observed for any of the other SNPs examined. Of all the SNPs analyzed, only rs1801275, an A > G transition nonsynonymous mutation, resulting in the substitution of glutamine by arginine showed an association, but it was statistically not significant. Interestingly, presence of the mutant allele of both SNPs of IL-13 gene significantly elevated IL-13 level. Comparison of the Saudi results with those of other populations, showed several significant differences. We conclude that further more detailed studies are necessary in Saudis to identify the contribution of SNPs in cytokine genes in asthma development.