There is strong evidence that NADPH oxidase is upregulated in affected regions during neurodegeneration, e.g., in an experimental model of Parkinson’s disease, activation of macrophages and microglia induced by NADPH oxidase triggered a subsequent production of ROS, thus damaging adjacent neurons, suggesting that the inflammatory process affecting a single region may spread to adjacent regions and hamper otherwise unaffected/healthy neurons [49–51]. The gene discussed is FMO5; the disease is Parkinson disease.