HomeGeneticsConditionAutosomal recessive spastic ataxia of Charlevoix-Saguenay
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Autosomal recessive spastic ataxia of Charlevoix-Saguenay
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Autosomal recessive spastic ataxia of Charlevoix-Saguenay

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an inherited condition affecting muscle movement, characterized by spasticity, balance issues, and peripheral neuropathy.

Overview and Symptoms

Autosomal recessive spastic ataxia of Charlevoix-Saguenay, more commonly known as ARSACS, is a condition affecting muscle movement. People with ARSACS typically have abnormal tensing of the muscles (spasticity), problems with balance and coordination (ataxia), and reduced sensation and weakness in the arms and legs (peripheral neuropathy).

Additional muscle problems that can occur in ARSACS include muscle wasting (amyotrophy), involuntary eye movements (nystagmus), and difficulty swallowing (dysphagia) and speaking (dysarthria). Other features of ARSACS involve high-arched feet, a spine that curves to the side (scoliosis), yellow streaks of fatty tissue in the light-sensitive tissue at the back of the eye (hypermyelination of the retina), bladder problems, intellectual disability, hearing loss, and recurrent seizures (epilepsy).

An unsteady walking style (gait) is the first symptom of ARSACS. Walking problems usually begin between the ages of 12 months and 18 months, as toddlers are learning to walk. These movement problems worsen over time, with increased spasticity and ataxia of the arms and legs. In some cases spasticity goes away, but this apparent improvement is thought to be due to the wasting away (atrophy) of nerves in the arms and legs. Most affected individuals require wheelchair assistance by the time they are in their thirties or forties.

While this condition was named after the area in which it was first seen, the Charlevoix-Saguenay region of Quebec, Canada, ARSACS has been identified in individuals worldwide.

Frequency

The incidence of ARSACS in the Charlevoix-Saguenay region is estimated to be 1 in 1,500 to 2,000 individuals. Outside of Quebec, the incidence of ARSACS is unknown. About 200 individuals with ARSACS have been described in the scientific literature.

Causes

Mutations in the SACS gene cause ARSACS. The SACS gene provides instructions for producing a protein called sacsin. Sacsin is primarily found in cells in the brain, skin, and muscles used for movement, but the specific function of the protein is unknown. Research suggests that sacsin plays a role in organizing proteins into bundles called intermediate filaments. Intermediate filaments provide support and strength to cells. In nerve cells, specialized intermediate filaments called neurofilaments comprise the structural framework that establishes the size and shape of nerve cell extensions called axons, which are essential for transmission of nerve impulses to other neurons and to muscle cells.

Mutations in the SACS gene cause the production of an unstable sacsin protein that does not function normally. It is unclear how the abnormal sacsin protein affects the brain and skeletal muscles, but it likely impairs normal organization of intermediate filaments in cells, particularly neurofilaments, and disrupts neuron function. This decreased neuronal signaling may result in the signs and symptoms of ARSACS.

Learn more about the gene associated with Autosomal recessive spastic ataxia of Charlevoix-Saguenay

  • SACS

Inheritance

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Other Names for This Condition

  • ARSACS
  • Charlevoix-Saguenay spastic ataxia
  • Spastic ataxia of Charlevoix-Saguenay
  • Spastic ataxia, Charlevoix-Saguenay type

Additional Information & Resources

  • Genetic Testing Registry: Charlevoix-Saguenay spastic ataxia
  • Genetic and Rare Diseases Information Center: Autosomal recessive spastic ataxia of Charlevoix-Saguenay
  • National Organization for Rare Disorders (NORD)
  • Clinical Trials
  • Catalog of Genes and Diseases from OMIM: SPASTIC ATAXIA, CHARLEVOIX-SAGUENAY TYPE; SACS
  • Scientific Articles on PubMed

Frequently Asked Questions

The first symptom of ARSACS is typically an unsteady walking style (gait), which usually becomes apparent between 12 and 18 months of age as toddlers learn to walk. Parents might notice frequent falls, clumsiness, or a wide-based gait. As the condition progresses, abnormal muscle tensing (spasticity) and problems with balance and coordination (ataxia) in the arms and legs become more noticeable.
Management of ARSACS focuses on supportive therapies to improve quality of life. Physical therapy is crucial to maintain muscle strength, flexibility, and balance, and to manage spasticity. Occupational therapy helps with daily living activities, and speech therapy can address difficulties with swallowing (dysphagia) and speaking (dysarthria). Medications may be used to help reduce spasticity.
s ARSACS progresses, individuals often require increasing support. Assistive devices such as walkers, canes, and eventually wheelchairs become necessary, typically by their thirties or forties, to maintain mobility. Home modifications, adaptive equipment for daily tasks, and ongoing medical monitoring for associated issues like bladder problems, hearing loss, or seizures are also important. A multidisciplinary care team provides comprehensive support.
utosomal recessive inheritance means that an individual must inherit two copies of the altered gene (one from each parent) to develop ARSACS. Parents who each carry one copy of the altered gene are typically unaffected but have a 25% chance with each pregnancy of having a child with ARSACS. Genetic testing can confirm a diagnosis, identify carriers, and provide crucial information for family planning and genetic counseling to assess risks for future children.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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