Although clinical evidence shows no correlation between APOE and ALS risk [254], APOE*ε2/2 ALS patients exhibit decreased glucose metabolism in extra-motor areas compared with APOE*ε3/3 homozygote patients, implying an increased risk of cognitive impairment associated with APOE*ε2 in ALS patients [255]. The gene discussed is APOE; the disease is amyotrophic lateral sclerosis.