SACS and Charlevoix-Saguenay spastic ataxia: In autosomal‐recessive spastic ataxia of Charlevoix Saguenay (ARSACS, because of biallelic mutations in SACS), abnormally elevated calcium‐rises in primary Sacs−/− PNs were described as the result of defective mitochondria and ER transport to the dendrites, because of intermediate filament cytoskeleton alterations (see Fig 3).116