FMO5 and infection: In spite of the fact that the NADPH oxidase is required for the efficient killing of a large spectrum of micro-organisms (Ellson et al. 2006; Zicha et al. 1997), some patients with autosomal recessive chronic granulomatous disease have decreased (but not absent) NADPH oxidase activity, and yet do not always have recurrent infections (Liese et al. 1996).