For example, an immunohistochemical study performed on post-mortem sporadic and superoxide dismutase 1 familial ALS human specimens and SOD1 familial ALS mouse models reported that the number of neurons negative for PrX2/glutathione peroxidase-1 (GPxl) increased with ALS disease progression [55]. The gene discussed is GPX1; the disease is amyotrophic lateral sclerosis.