ATXN2 and amyotrophic lateral sclerosis: A high frequency of 27Q repeats was noticed in ALS patients, Parkinson's disease (PD) patients, and controls in Europe and North America (Figure 2a), but not in Chinese ALS patients or healthy controls (Figure 2b), where the peak of 27 CAG repeats in the ATXN2 gene was essentially absent [58], [59].