SOD1 and amyotrophic lateral sclerosis: More recently, we investigated blood DNA samples from 114 individuals, including ALS patients, presymptomatic carriers of ALS-causative mutations, and noncarrier family members, and observed a significantly decreased methylation of the mtDNA D-loop region in carriers of ALS-linked SOD1 mutations (either ALS patients or presymtomatic carriers) with respect to noncarriers of ALS-gene mutations or to carriers of mutations in other ALS-causative genes (FUS, TARDBP, C9orf72).