WAS and inborn error of immunity: Wiskott-Aldrich syndrome is a rare, X-linked, primary immunodeficiency characterised by microthrombocytopenia, recurrent infections, eczema, and increased risk for autoimmunity and lymphoid malignant diseases.1, 2 The disease is due to mutations in the WAS gene, which encodes the Wiskott-Aldrich syndrome protein (referred to as WASP)—an intracellular key regulator of actin polymerisation.2, 3 WASP-deficient immune cells have compromised immunological synapsis formation, cell migration, and cytotoxicity.1