Loss of function mutations in RIPK4 have been identified in patients with a popliteal-pterygium syndrome (Bartsocas-Papas syndrome) characterised by numerous craniofacial, musculoskeletal, genitourinary, gastrointestinal, cardiac and neurodevelopmental defects, resembling IKKα deficiency (68, 146, 147). The gene discussed is RIPK4; the disease is Bartsocas-Papas syndrome 1.