FMO5 and chronic kidney disease: The genetic deletion or overexpression of NOX4, a major NADPH oxidase isoform in the kidney, does not affect the pathogenesis of CKD in vivo (Rajaram et al., 2019; Thallas-Bonke et al., 2020), indicating that other sources of ROS or additional yet unknown mechanism(s) are involved in the pathogenesis of renal dysfunction.