In patients with severe asthma, there is strong association, measured by Spearman rank correlation, between BAL IL‐13 and IL‐ 4 concentrations, r = 0.749, p < 0.001 but weaker association between BAL IL‐13 and IL‐5 concentrations, 0.410, p < 0001. This evidence concerns the gene IL13 and asthma.