The ranges of CAG repeats roughly determines the age of disease onset and hence, clinical presentation in children with autosomal dominant spinocerebellar ataxia type 7 (SCA7). In addition, the age at ataxia onset may be the best predictor of the age at loss of ambulation and of the age at death.
Why this matters
SCA7 is a neurodegenerative disorder associated with progressive blindness caused by pathological CAG repeat expansions in the ATXN7 gene. Previous studies have found the number of CAG repeats determines the age of onset of disease and clinical presentation patterns. Reassessing this phenotypic classification and establishing potential correlations of these to parameters of natural history may help to predict the course of the disease and could be used for evaluating the efficacy of future therapeutic approaches.