Objective: To describe the prevalence and clinical characteristics of Autosomal Dominant (AD) Spinocerebellar Ataxias (SCA) in a Canadian cohort of patients in Ontario.

Background: SCAs are a group of AD progressive neurodegenerative disorders. SCAs typically have onset in adulthood and are seen in a variety of ethnic backgrounds. The only previous Canadian study of SCAs was from Alberta Canada and included 69 patients with the most prevalent SCAs being SCA3 (23.8%), SCA2 (14.3%), and SCA 6(9.5%) (1).  Our goal was to determine the prevalence of AD SCAs in individuals > 18 years old, at our centre and describe their demographics and clinical characteristics.

Method: A retrospective chart review of patients from the Movement Disorders clinic at Toronto Western Hospital, which has a large catchment area, seeing referrals from throughout Ontario. Patients with AD SCA (age of onset > 18), who were seen between Jan 1st 2000 and Jan 1st 2021 were included.

Results: We analyzed the clinical characteristics and genetic backgrounds of 111 patients with AD SCAs, which is one of the largest cohorts reported from a single center. We found that the most common SCAs in our cohort are SCA 3 (50.4%), SCA1(14.5%), SCA2 (12.6%) and SCA6 (5.4%). Other less common SCAs found include: SCA7,14,15 and 35 (1.8% each). We had single cases with SCA5,10,12,21,28,31, and 40. The majority of our patients were of Caucasian (33.6%), Asian (30.9%), and Portuguese (26.3%) origins. The mean age of presentation in all patients was 39.8 years. The mean disease duration of the cohort described was 13 years. Majority of our cohort patients presented with gait abnormalities as their initial complaint (75%). The most common associated movement disorders were dystonia (31.8% – SCA3 (54.2%) and SCA2 (14.2%)) and parkinsonism (23% – SCA3 (68%), SCA1(8%), and SCA2(8%)). Chorea and myoclonus were rare.

Conclusion: We report the prevalence and clinical characteristics of a large cohort with AD SCAs from a single center in Toronto, Canada. The most prevalent SCA in our cohort of 111 patients, is SCA3 partially reflecting the large Portuguese community within Ontario. Other common SCAs included SCA1 and SCA2. The prevalence of SCA1 in our population is higher than in the previously reported Canadian cohort from Alberta. We suspect that this finding reflects the ethnic heterogeneity of Canada which varies from province to province.

References: (1) Kraft S, Furtado S, Ranawaya R, Parboosingh J, Bleoo S, McElligott K, Bridge P, Spacey S, Das S, Suchowersky O. Adult onset spinocerebellar ataxia in a Canadian movement disorders clinic. Canadian journal of neurological sciences. 2005

« Back to MDS Virtual Congress 2021

MDS Abstracts - https://www.mdsabstracts.org/abstract/prevalence-and-clinical-characteristics-of-autosomal-dominant-spinocerebellar-ataxia-in-a-large-canadian-cohort-from-ontario/