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Título

Spinocerebellar ataxias in the state of Alagoas

Resumo

Spinocerebellar ataxias (SCAs) are a group of autosomal dominant ataxias characterized by dysfunction of the cerebellum and its connections besides additional manifestations, such as pyramidal and extrapyramidal signs, peripheral neuropathy, visual impairment and epilepsy. SCAs have an average worldwide prevalence of 2.7 cases per 100,000 individuals and great ethinc and geographic variability. In Brazil, epidemiological studies are based on data obtained mostly at neurogenetic reference centers in south and southeast regions and some regions are still underrepresented. The present study aimed to identify and characterize SCAs in the state of Alagoas in order to contribute to the epidemiological and clinical profile of SCAs and to stimulate the development of strategies to detect people with SCA in regions without epidemiological data. From June 2018 to August 2021, we carried out active search strategies for people with a diagnosis or clinical suspicion of SCA and applied a clinical and molecular evaluation protocol that included clinical interview, heredogram construction, neurological exam, ataxia and functional scales and molecular analysis for SCAs type 1, 3, 6, 7,8,10, 12, 17 and DPRLA. As a result, 73 people with SCA were identified, configuring a minimum estimated prevalence of 2.17 cases per 100,000 inhabitants, distributed as 75.3% patients with SCA3, 15.1% with SCA7, 6.8% with SCA1 and 2.7% with SCA2. SCA3 and SCA7 analysis showed age at onset and clinical features congruent with other studies; predominance of SCA3 subphenotype 2; gait alterations as the main initial manifestation and, in people with SCA7, accompanied by reduced visual capacity; inverse correlation between age at onset and number of expanded CAG; positive correlation between severity and disability scales and duration of illness; and that most people affected are not engaged in a rehabilitation program and there are large numbers of asymptomatic people at risk of developing SCA. Therefore, this study show that simple collaborative strategies can enhance the detection capacity of SCA families and demonstrate that Alagoas has a minimum estimated prevalence of SCA similar to the world average prevalence.

Palavras Chave

Spinocerebellar ataxias. Spinocerebellar degenerations. Machado-Joseph Disease. Spinocerebellar ataxia type3. Spinocerebellar ataxia type7. Prevalence