Hereditary Ataxias: A Genetic Epidemiological Study of a Danish Clinical Cohort

Background: Ataxia, characterized by incoordination of movement, presents a diverse etiological spectrum, including genetic forms such as spinocerebellar ataxias (SCAs), Friedreich’s ataxia (FRDA), and other hereditary ataxias. Identifying and understanding the distribution of the genetic subtypes in specific populations are crucial for clinical management, genetic counseling, and prognostication. Objective: This study is aimed at investigating the genetic epidemiology of hereditary ataxias in a clinical cohort from Eastern Denmark, focusing on the prevalence and distribution of the genetic ataxias. Methods: We conducted a chart review of 297 patients diagnosed with ataxia from the two major referral centers in Eastern Denmark between 2018 and 2023. Diagnoses were divided into groups: confirmed genetic ataxia, presumed genetic ataxia (no genetic variant identified, positive family history) and possible genetic ataxia (debut before the age of 40, no family history), sporadic adult-onset ataxia (SAOA) (debut after the age of 40, no family history), and multiple system atrophy–cerebellar type (MSA-C)). Data collected included demographics, clinical features, age of onset, and results of genetic testing. Results: Of the 297 patients, 144 (48.5%) had a confirmed genetic ataxia, 26 (8.8%) were classified as presumed genetic ataxia, and 19 (6.4%) were categorized as possible genetic ataxia. The most common subtypes were SCA6, SCA2, and SCA3. The study revealed notable differences in the prevalence of specific ataxia subtypes compared to global patterns. Conclusion: This study provides an overview of the epidemiology and genetic landscape of hereditary ataxias in Denmark. The high prevalence of SCA6 and unique distribution patterns emphasizes the need for population-specific data to guide clinical practice. Ongoing trials for SCA1 and SCA3 highlight the importance of understanding the epidemiology of ataxias across different countries to establish trial-ready cohorts and address future treatment needs.