The hypersensitivity reaction classified by the British immunologists, Philip Gell and Robin Coombs, as the type 1 reaction (now also named the IgE-mediated allergic reaction, but notably IgE had still not been discovered and named in 1963, when Gell and Coombs first suggested their classification of this humoral form of hypersensitivity), still provides the basic theoretical framework for our discussion of anaphylaxis. The gene discussed is IGHE; the disease is allergic disease.