Cytochrome b -245 is a primary component of the microbicidal oxidase system of phagocytes encoded by the alpha and beta chains CYBA and CYBB/Nox2 (NADPH oxidase 2), respectively (Stasia, 2016), and cytochrome b deficiency is also linked to CGD (Clark, 1999; Stasia et al., 2003; Kutukculer et al., 2019). The gene discussed is CYBB; the disease is chronic granulomatous disease.