Enlarging the clinical spectrum associated with C9orf 72 repeat expansions: Findings in an Italian cohort of patients with Parkinsonian syndromes and relevance for genetic counselling

摘要

An expanded hexanucleotide repeat (GGGGCC) in the C9orf72 gene was recently identified as an important cause of frontotemporal dementia (FTD), of motor neuron disease (ALS) or both (ALS-FTD) (1,2). A wide variability, both in disease presentation and in the clinical course, has been described in different patients' cohorts (3,4). It remains unclear, however, how common this repeat is in different pop- ulations and what phenotypic spectrum is associated with this mutation. Previous papers investigated the allele frequency of C9orf72 expansion in ALS, FTD, as well as in Alzheimer's disease and finally in Parkin- son's disease (PD) (5,6). Clinical features overlapping with FTD have been noted in various Parkinsonian syndromes such as progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) (4).