Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is an inherited disorder that impacts the body’s sacsin protein production, typically found in the brain, skin, and muscles.
The initial sign, an unsteady gait, emerges around 12 to 18 months of age, coinciding with toddlers’ early walking attempts. Speech difficulties ensue due to weakened neck and facial muscles. Over time, ARSACS progresses, leading to muscle tension, spasms, poor movement coordination, involuntary eye motions, and muscle degeneration. Additional effects encompass sensory loss in limbs, incontinence, hand and foot deformities, retinal fat accumulation affecting vision, and sporadic heart valve leaks. Though most individuals retain normal intelligence and independent living well into adulthood, the capacity to walk eventually diminishes.
ARSACS is caused by pathogenic (disease-causing) variants in the SACS gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a 1 in 483 chance to be a carrier.
Other names for this condition are Charlevoix-Saguenay spastic ataxia and spastic ataxia of Charlevoix-Saguenay.
Resources:
Ataxia Charlevoix-Saguenay Foundation
Revised August 2023
