C9ORF72 repeat expansion is not a significant cause of late onset cerebellar ataxia syndrome.

The GGGGCC hexanucleotide expansion in the C9ORF72 gene is the most common cause of familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) in Caucasian populations. The phenotypic spectrum of C9ORF72 hexanucleotide repeat expansion mutation has been reported to include parkinsonian syndrome, Huntington's disease-like syndrome and dementia syndrome. Although few individuals with cerebellar ataxia have also anecdotally been found to harbor the mutation, the relationship between the mutation and cerebellar ataxia awaits further clarification. We hereby screened for the presence of the C9ORF72 hexanucleotide repeat expansion in 331 patients with multiple system atrophy-cerebellar variant and 98 unrelated patients with molecularly un-assigned spinocerebellar ataxia in Taiwan utilizing a repeat-primed polymerase chain reaction assay. We found that none of the 429 patients had the C9ORF72 hexanucleotide repeat expansion mutation. Therefore, our study does not support that the mutation plays a significant role in cerebellar ataxia.