Based on the mechanism involved, CMA can be further classified into (a) IgE-mediated, which is caused by antibodies against milk proteins belonging to IgE, (b) non-IgE (or cell-mediated), where the cellular immune system, and especially T-cells, are responsible for the allergic reaction, and (c) mixed type when both IgE and immune cells are involved [18]. This evidence concerns the gene IGHE and allergic disease.