NCF4 and immunodeficiency disease: Chronic granulomatous disease is an immunodeficiency disease caused by defects in any of the five structural components of the NOX enzyme, i.e., X-linked recessive mutations in Cybb (gp91phox), or autosomal recessive mutations in Cyba (p22phox), Ncf1 (p47phox), Ncf2 (p67phox), or Ncf4 (p40phox) (Kuhns et al., 2010; Arnold and Heimall, 2017; van de Geer et al., 2018).