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New hope in the face of a devastating disease

Descendants of French-Canadian families who settled in the Charlevoix-Saguenay region of New France back in the 17th century have reason to be optimistic about the findings of a team led by researchers at the Montreal Neurological Institute and Hospital (The Neuro) at McGill.

A devastating neurodegenerative disease known as ARSACS (Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay) first appears in toddlers just as they’re beginning to walk. The researchers have traced it to defects in mitochondria, the “batteries” or energy-producing power plants of cells.

The disorder primarily affects the cerebellum, a centre for movement coordination in the brain, and was first identified in a large group of patients from Quebec’s Charlevoix and Saguenay regions in the late 1970’s. One of every 1,500-2,000 members of this “founder” population is born with the condition, and one in 23 are carriers. Although prevalent here, ARSACS is not unique to Quebec – scientists have found more than 100 separate mutations in places like Japan, Turkey and Western Europe.

ARSACS strikes at an early age. Symptoms, which worsen over time, include poor motor coordination, spastic stiffness, muscle wasting, uncoordinated eye movements and slurred speech. Most patients are wheelchair-bound by their early 40’s and have a reduced life expectancy.

In 2000, scientists identified the gene associated with the disease, called SACS, which produces a massive 4,579-amino-acid protein called sacsin, but until now the protein’s role has been unknown. According to neurologist Dr. Bernard Brais at The Neuro, “This finding is the first important advancement in the 10 years since the identification of the mutated gene because it gives an indication of the underlying cellular mechanism of the disease and is a vital first step towards developing therapeutic strategies for ARSACS.”

The multi-institutional collaborative research was led by Dr. Brais and Dr. Peter McPherson at The Neuro and Dr. Paul Chapple at Queen Mary, University of London. Its findings significantly increase our understanding of the disease, revealing an important common link with other neurodegenerative diseases like Parkinson, Alzheimer, and Huntington disease as well. 

This research was funded by the Fondation de l’Ataxie de Charlevoix-Saguenay, created by parents with children are affected by this orphan disease. The foundation works to increase awareness of the disease and raise funds for research to find a treatment.