Researchers have shed light on the molecular events underlying a genetic movement and neurodegenerative disorder known as ARSACS – Charlevoix-Saguenay’s autosomal recessive spastic ataxia, named after two valleys in Quebec where the first cases were discovered. The findings of the study have been published in Cell Reports. Children with ARSACS typically present with walking difficulties in the second year of life and an increasing number of neurological problems thereafter. In the cerebellum — an area of the brain that coordinates movement and balance — neurons called Purkinje cells die in individuals with ARSACS. Most patients are wheelchair-bound between the ages of 30 and 40 and have a shortened lifespan averaging their mid-50s. The condition is caused by the mutation and functional loss of a gene called SACS that codes for a very large protein called sacsin, which difficult to study directly, in part because of its unwieldy size. Relatively little is known about its normal functions and how its absence leads to disease. The collaborating researchers conducted the most comprehensive analysis of what happens in cells when sacsin is missing.