SACS and Autosomal recessive spastic ataxia of Charlevoix-Saguenay: ARSACS is associated with loss-of-function variants in the SACS gene [5], leading to depletion of sacsin, a ∼520 kDa large multidomain protein widely expressed in layer 5 corticospinal neurons, anterior commissure, anterodorsal nuclei of thalami, Purkinje cells and brainstem nuclei [6, 7].