ATXN2 and amyotrophic lateral sclerosis: There are a small number of reports where full-length ≥34 CAG-repeat ATXN2 expansions are associated with familial ALS, or the related disorder frontotemporal dementia (FTD) [7, 8], but the current consensus is that ATXN2 CAG-repeat expansions are not routinely associated with familial ALS, and full-length expansions are not routinely associated with ALS in general [9].