ATXN3 and Spinocerebellar ataxia type 3: In cohort #1 (Fig 1E), SCA3 subjects at the ataxic stage had significantly higher serum pNfH concentrations (110.2 pg/ml [42.9–277.9]) than controls (22.8 pg/ml [13.9–59.1]; U = 1,064, z = 6.72, P < 0.001, r = 0.55, Bonferroni‐corrected), while pNfH concentrations in preataxic SCA3 subjects (33.9 pg/ml [18.0–184.8]) were not significantly increased compared to controls (U = 201, z = 1.61, P = 0.109, r = 0.17).