Autosomal recessive spastic ataxia of Charlevoix-Saguenay

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS), also known as spastic ataxia Charlevoix-Saguenay type or SACS-related ataxia, is a rare inherited neurodegenerative disorder caused by mutations in the SACS gene on chromosome 13q12.12, which encodes the protein sacsin. The disease was first described in the Charlevoix-Saguenay-Lac-Saint-Jean region of Quebec, Canada, where it has a notably high carrier frequency, but cases have since been identified worldwide across diverse ethnic backgrounds. ARSACS primarily affects the nervous system, with the hallmark clinical triad consisting of early-onset cerebellar ataxia (impaired coordination and balance), lower limb spasticity (stiffness due to pyramidal tract involvement), and peripheral neuropathy (damage to the nerves outside the brain and spinal cord). Symptoms typically begin in early childhood when children start walking, often presenting with an unsteady gait and frequent falls. Over time, patients develop progressive difficulty with walking, speech (dysarthria), and fine motor tasks. Additional features may include hypermyelination of retinal nerve fibers visible on fundoscopic examination, distal muscle wasting, pes cavus (high-arched feet), and urinary urgency. Brain MRI characteristically shows superior cerebellar vermis atrophy and linear hypointensities in the pons. The disease is progressive, and most patients require a wheelchair by the third or fourth decade of life, though the rate of progression varies. There is currently no cure or disease-modifying treatment for ARSACS. Management is supportive and multidisciplinary, including physical therapy to maintain mobility and manage spasticity, occupational therapy, speech therapy for dysarthria, and orthopedic interventions as needed. Antispasticity medications such as baclofen may be used to alleviate muscle stiffness. Regular monitoring by neurologists, ophthalmologists, and rehabilitation specialists is recommended.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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