The results indicated that allele A of LTA4H A-9188>G (rs2660845), allele G of TNFα G-308>A (rs1800629) and allele A of IL-4Rα A1727>G (rs1801275) were all significantly associated with difficult asthma in paediatric patients after adjusting for multiple testing (p<0.001, p = 0.019 and p = 0.037, respectively). This evidence concerns the gene TNF and asthma.