Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay

Gene : SACS

What is Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay?

Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS) is an inherited disorder that affects muscle movement. The first symptom of ARSACS is an unsteady gait that usually appears between the age of 12 months and 18 months, as toddlers are learning to walk. The signs and symptoms worsen over the years, with increased abnormal tensing of the muscles, difficulty coordinating movements, muscle wasting, involuntary eye movements, and speech difficulties. Other problems may include deformities of the fingers and feet, pain in the hands and feet, abnormal foot reflexes, loss of the sensation of touch, yellow streaks of fatty tissue in the light-sensitive tissue at the back of the eye, and possible heart defect. Muscles continue to deteriorate to the point that most affected individuals require a wheelchair by the time they are adults. Affected individuals have a mental capacity that is at the lower end of the expected range for their age and are able to perform daily tasks throughout their lifetime. There is no cure for ARSACS; however medical surveillance and care may help to improve some symptoms and overall condition of life. ARSACS is caused by pathogenic variants in the SACS gene.

How is Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay inherited?

ARSACS is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for ARSACS. However, the risk to have a child affected with ARSACS is increased. Testing of reproductive partners is recommended for carriers of ARSACS.

How common is Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay?

ARSACS was initially described in the Charlevoix-Saguenay region of Quebec where it affects 1 in 1,932 newborns. Outside of Quebec, ARSACS is rare, and how often it occurs is unknown.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems


Carrier Rates
Detection Rate
Carrier Frequency
General Population > 99% 1 in 500

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