IGHE and allergic disease: The most commonly accepted and well‐defined endotype of allergic diseases is one encompassed by eosinophilic inflammation resulting from type 2 (T2) cells including CD4+ T helper 2 (Th2) cells, group 2 innate lymphoid cells (ILC2s), type 2 cytotoxic T (Tc2) cells and mast cells as well as T2 inflammatory mediators such as interleukin (IL) ‐4, IL‐5, IL‐13 and immunoglobulin E (IgE).26