Tumor Necrosis Factor-α (-308G>A) Gene Polymorphism and Its Association with Asthma and Atopy Status

Asthma is one of the most prevalent chronic lung diseases that afflict genetically predisposed individuals. Certain cytokine gene polymorphisms have been associated with asthma. Tumor necrosis factor-alpha (TNF-α) is a potent inflammatory cytokine that can modulate nonspecific inflammation to influence asthma. This study aimed to define the relationship between the TNF gene polymorphism at position -308 and asthma susceptibility, as well as atopic and non-atopic asthma. Using polymerase chain reaction with sequence-specific primers, we investigated genotype frequencies and alleles of a polymorphic gene coding for TNF-α in 86 pediatric patients with asthma and 470 healthy controls of the same race. Seventy-four patients underwent a skin prick test. The homozygous AA variant (-308, rs1800629) was the most common genotype among patients, accounting for 63.3% of all cases. In contrast, homozygous GG (-308) was significantly less prevalent in the patient group compared to the control group. TNF A (-308) allele frequency was 85.5% among asthma patients and 16.6% among healthy controls. The genotype and allele frequencies of TNF (-308 A>G, rs1800629) did not differ between atopic and non-atopic asthma. In conclusion, TNF (-308) AA and AG genotypes are associated with asthma susceptibility in Iranian children, although there was no significant difference in polymorphism between atopic and non-atopic asthma and no difference in asthma severity groups.