SOD1 and amyotrophic lateral sclerosis: However, it is possible that the increased prevalence of H63D HFE in ALS patients is due less to this variant increasing the risk of disease but is, in fact, due to the increased disease duration found in ALS patients with H63D HFE [57,63,118], although one study only found this trend in ALS patients also carrying superoxide dismutase [Cu-Zn] (SOD1) mutations (one of the most common genetic mutations in ALS patients) [57].