Conversely, ROS may facilitate neurotoxic protein aggregation, such as amyloid-β (in AD), α-synuclein (in PD) and SOD1 (in ALS), as well as mitochondrial impairment, producing a vicious cycle among oxidative stress, mitochondrial dysfunction and protein aggregation [8,9]. The gene discussed is SOD1; the disease is amyotrophic lateral sclerosis.