Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS)
Summary
ARSACS is a progressive neurological condition affecting the cerebellum and spinal cord. Sacsin is a very large protein involved in mitochondrial dynamics and protein quality control in neurons. Deficiency causes degeneration of cerebellar and spinal motor neurons.
Practical takeaway
Particularly relevant if your partner is of French Canadian descent (especially from the Charlevoix or Saguenay-Lac-Saint-Jean region). A carrier test can determine partner status. Realised does not calculate reproductive risk or advise on reproductive decisions.
Evidence detail
What Carrier Status Means For You
You are not affected. One working copy of SACS is sufficient. Standard 25/50/25 recessive inheritance applies.
Population Context
ARSACS has one of the highest carrier frequencies of any neurological condition, but this is concentrated in the Charlevoix-Saguenay region of Quebec (~1 in 22). The condition was first described there in 1978. Cases have since been identified worldwide involving different SACS variants, but at much lower frequencies.
Limitations
23andMe tests 1 SACS variant (the French Canadian founder). For non-French-Canadian individuals, coverage is minimal. Over 200 pathogenic SACS variants have been identified.