The considerable spinocerebellar tract pathology detected in C9orf72 negative ALS-FTD and nfvPPA and the anterior cerebellar lobe atrophy captured in C9POS ALS-FTD unravel one of the substrates of gait impairment and disequilibrium in these cohorts. This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.