C9orf72 and amyotrophic lateral sclerosis: Of note, variations in epigenetic marks and modifier enzymes, and alterations in the methylation status of some ALS-related genes promoters were also determined, including hypomethylation of OPTN, hypermethylation of C9orf72 expansion CpG islands in the blood of FTD/ALS patients, whereas mutant SOD1, FUS and TDP43 contribute to global epigenome alteration by inducing alterations in histone post-translational modifications and DNA methylation (Masala et al., 2018).