SACS and Autosomal recessive spastic ataxia of Charlevoix-Saguenay: Autosomal-recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is caused by loss-of-function mutation in the <i>SACS</i> gene, which encodes sacsin, a putative HSP70-HSP90 co-chaperone.