Examples are a variant of immune dysregulation polyendocrinopathy X-linked syndrome due to a mutation in the forkhead box P3 gene (FOXP3) in which most patients are characterized by the clinical triad of intractable diarrhoea, insulin-dependent diabetes and eczematous dermatitis but some of them, show severe food allergy and hyper-IgE autosomal dominant syndrome with dedicator of cytokinesis 8 (DOCK8) gene mutation. Here, DOCK8 is linked to type 1 diabetes mellitus.