Significant Contributions of Interleukin-13 Genotypes to Asthma Severity

Asthma is a complex inflammatory airway disease influenced by genetic and environmental factors. Interleukin-13 (IL-13), particularly its promoter polymorphism rs1800925 and coding variant rs20541, have been implicated in asthma pathogenesis. This study investigated their associations with asthma susceptibility and severity in a Taiwanese population. A total of 198 adult patients with asthma and 453 controls without asthma were genotyped for IL-13 rs1800925 and rs20541 using PCR-based assays. Associations with disease risk, age, sex, and asthma severity were analyzed using logistic regression models. Genotype frequencies of IL-13 rs1800925 and rs20541 conformed to Hardy-Weinberg equilibrium in controls (p =0.1209 and 0.6860). No significant association was found between asthma risk and rs1800925 CT versus CC: odds ratio (OR)=1.16, 95% confidence interval (CI)=0.80-1.65, p=0.4793; TT versus CC: OR=1.31, 95%CI=0.70-2.45, p=0.5043 or rs20541 (AG versus GG: OR=0.93, 95%CI=0.66-1.33, p=0.7652; AA versus GG: OR=0.84, 95%CI=0.46-1.51, p=0.6577). However, stratified analysis revealed that among individuals aged 25-40, the rs1800925 TT genotype was associated with increased asthma risk (OR=2.16, 95%CI=1.02-4.56, p=0.0637). Notably, rs1800925 CT and TT genotypes were significantly associated with severe asthma symptoms (CT versus CC: OR=2.11, p=0.0287; TT versus CC: OR=4.83, p=0.0057), with carriers of CT+TT genotypes having higher odds of severe asthma (OR=2.46, 95%CI=1.36-4.45, p=0.0041). While IL-13 rs1800925 and rs20541 polymorphisms were not significantly associated with overall asthma susceptibility, the rs1800925 TT genotype may confer increased risk in younger adults and is significantly linked to more severe asthma severity. IL-13 rs1800925 may serve as a potential genetic biomarker for asthma severity prediction and management in Taiwanese populations.