Association between FOXO3a Gene Polymorphism and Susceptibility to Asthma in South Indian Population

Background: Asthma is an important cause of morbidity worldwide. The FOXO3a gene plays an important role in human immune regulation and homeostasis. Loss of function may lead to chronic inflammation and asthma. Objective: To evaluate the association between Foxo3a gene polymorphism and susceptibility to asthma. Methods: We conducted a case-control study in a tertiary care hospital. Participants answered a questionnaire that collected demographic and clinical information. Asthma was confirmed by pre and post bronchodilator spirometry. Genotyping of the FOXO3a polymorphisms was performed using PCR-RFLP. Results: The study population included 41 cases and 33 controls. Among cases, the heterozygous (CT) genotype frequency was greater compared to wild homozygous (CC) and mutant homozygous (TT) variants. In controls, the wild homozygous (CC) genotype frequency was greater compared to heterozygous and mutant homozygous variants. In the general model, the mutant homozygous (TT) group had significantly higher odds of 7.8 (1.78-34.07) of having asthma compared to the wild homozygous (CC) group. The mutant homozygous (TT) group had greater severity of asthma as compared to the wild homozygous (CC) group. The mutant homozygous group (TT) had much lower lung functions, as compared to the wild homozygous (CC) group in asthmatics. Among nonasthmatic controls, lower lung functions were seen in the mutant (TT) group as compared to the wild (CC) group. Conclusion: We found a significant association between the Foxo3a gene polymorphism and asthma. The T allele, a variant of the Foxo3a gene polymorphism, is associated with a higher risk of asthma, and greater asthma severity. It is also associated with lower lung functions in both asthmatics and apparently healthy control subjects.