Clinical Guidance
ARSACS (autosomal recessive spastic ataxia of Charlevoix-Saguenay) defines a spastic ataxia first described in 1978 among a cohort of about 325 French-Canadian individuals from 200 families born in the Saguenay-Lac-St-Jean area of northeastern Quebec . The disorder has since been identified in other areas of the world . Most individuals display a slowly progressive course of unsteadiness, often with onset before age ten years (usually of late-infantile onset) and associated with spasticity during childhood and neuropathy during teenage years. In addition to the classic triad of symptoms of progressive cerebellar ataxia, peripheral neuropathy, and lower-limb spasticity, some individuals with ARSACS have features such as hearing loss, intellectual disability, and myoclonic epilepsy [, , , , , ]. Furthermore, absence of one of the three defining clinical features has been described in several individuals [, , , , , ]. Both intra- and interfamilial phenotypic variability has been observed in ARSACS. To date, more than 190 individuals have been identified with biallelic pathogenic variants in SACS [, , , , , ] (LOVD3 Database). The following table of the phenotypic features associated with this condition is based on the table in the publication of . Note: Not all features were measured in the different groups of affected individuals; some relative frequencies are less representative due to a lower total number of individuals measured. Table 2. Features of ARSACS
