In particular, the GSR T>C and IL5 C-703T genes in men and the CYBA 640A>G, PON2 C311S, and GPX4 C718T loci in women had the highest degree of synergy in their interactions to determine the susceptibility to allergic asthma, whereas the highest degree of synergy in gene-gene interactions in nonallergic asthma in men was found for the CYBA −930A>G, FMO3 E158K, and GPX1 P198L loci. This evidence concerns the gene FMO3 and allergic asthma.