Interestingly, epigenetic differences in discordant monozygotic twins have been reported for amyotrophic lateral sclerosis, a devastating late-onset neurodegenerative condition in which the ATXN2 gene can be also implicated, but not differential methylation within its specific promoter was observed among the discordant twins [29]. This evidence concerns the gene ATXN2 and amyotrophic lateral sclerosis.