Interleukin-4 (C590T) Gene Polymorphism in Association with Asthma Severity

Abstract

Mona Al-Ahmad,1,2,* Asmaa Ali,2– 4,* Mohammad Z Haider5 1Department of Microbiology, College of Medicine, Kuwait University, Kuwait City, Kuwait; 2Department of Allergy, Al-Rashed Allergy Center, Ministry of Health, Kuwait City, Kuwait; 3Department of Laboratory Medicine, School of Medicine, Jiangsu University, Zhenjiang, People’s Republic of China; 4Department of Pulmonary Medicine, Abbassia Chest Hospital, Ministry of Health, Cairo, Egypt; 5Department of Pediatrics, College of Medicine, Kuwait University, Kuwait City, Kuwait*These authors contributed equally to this workCorrespondence: Mona Al-Ahmad, Department of Microbiology, College of Medicine, Kuwait University, Kuwait City, Kuwait, Tel [phone], Fax [phone], Email [email protected]: A significant link between T allele of the IL-4 (C590T) gene and developing asthma in some populations was reported. However, no study discussed the link between IL-4 (C590T) gene polymorphism and asthma severity groups (mild and severe). This study investigated the link between IL-4 gene variation and asthma severity.Methods: The study included 215 asthmatic patients, of which 102 had mild asthma, and 126 participants were healthy controls. A previously published polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to identify various IL-4 (C590T) gene polymorphism genotypes.Results: The T allele frequency was higher in mild asthma (p=0.002) but not in severe asthma (p=0.12) compared to controls. In mild asthma, the CT genotype and (CT+TT versus CC) increased the likelihood of asthma threefold (p< 0.001, 0.001). However, no significant association with severe asthma was found in either genetic model. Stratification analysis showed that the C allele and CC genotype increased the risk of severe asthma (p=0.01). The recessive genetic model indicated a decrease in the risk of severe asthma (OR=0.5, p=0.01) in the non-adjusted regression analysis. Adjusting for age, sex, and other risk factors revealed that the IL-4 gene polymorphism did not influence the risk of severe asthma (OR=0.92, p=0.80); however, being an elderly female with a history of childhood-onset disease and associated nasal polyp (NP) increased the likelihood of severe asthma, OR=1.08, 2.01, 2.36, 8.42; p< 0.001, 0.05, 0.05, < 0.001, respectively.Conclusion: The T allele and CT genotype in the co-dominant genetic model and the (CT+TT) genotype in the recessive model were found to have a higher likelihood of developing mild asthma but not severe asthma; severe asthma was found to be higher in elderly females with a history of childhood-onset disease and associated nasal polyps.Keywords: IL-4 (C590T) gene polymorphism, mild and severe asthma, nasal polyp

Keywords

• il-4 (c590t) gene polymorphism
• mild and severe asthma
• nasal polyp