ATXN2 and amyotrophic lateral sclerosis: Remarkably, human homologs of these yeast modifier genes have confirmed, and identified new human risk factors for Alzheimer’s (PICALM, XPO1, ADSSL1 and RABGEF1) [38–40], Parkinson’s (PARK9) [38,41]) and ALS (ATXN2) [42–46].