Rare defects in serine/threonine-protein kinase 4 (STK4), which is upstream of DOCK8, have also demonstrated combined immunodeficiencies with many of the expanded features of WAS and DOCK8 deficiency including poor viral control, malignancy, autoimmunity, severe atopic dermatitis, eosinophilia, and elevated IgE (53, 54). Here, STK4 is linked to immune system disorder.