Significantly, our data identified that maximal IL1RL1 signalling occurs in cells carrying both asthma IL1RL1 risk variants in the extracellular and TIR domains, that is, the protein sequence that contains Ala78 and Ala433‐Glu501‐Thr549‐Leu551 together. This evidence concerns the gene IL1RL1 and asthma.