Trinucleotide CAG expansions of the ataxin‐2 protein, encoded by the ATXN2 gene, increase the susceptibility to amyotrophic lateral sclerosis; in contrast, prolonged expansion leads to spinocerebellar ataxia‐2 (SCA2), an autosomal dominant neurodegenerative disease (Chio et al., 2015; Pulst et al., 1996). The gene discussed is ATXN2; the disease is amyotrophic lateral sclerosis.