DOCK8 deficiency causes combined immunodeficiency (CID) with complex pathological features: impaired immune cell chemotaxis and synapse formation at cellular level; disrupted WASp–Arp2/3‐mediated actin reorganization at molecular level; and Treg dysfunction, Th2 bias, and skin barrier defects at systemic level, clinically manifesting as eczema, recurrent infections, and severe allergies [192, 193]. This evidence concerns the gene WAS and combined immunodeficiency.