ATXN2 and amyotrophic lateral sclerosis: The initial observation that ataxin-2 acts as a modifier protein of TDP-43 overexpression toxicity as a model of ALS risk was consistent from Saccharomyces cerevisiae via Drosophila melanogaster to Homo sapiens[14], and the role of ATXN2 intermediate expansions as ALS risk factor was reproduced in every follow-up study [15], [16], [17], [18], [19], [20], [21], [22], [34], [41], [42].