C9orf72 and frontotemporal dementia: C9Orf72 mutations have been related to bvFTD, frontotemporaldementia-amyotrophic lateral sclerosis (FTD-ALS), nonfluent variant primaryprogressive aphasia (nfvPPA), corticobasal syndrome (CBS), and rarely semanticvariant primary progressive aphasia (svPPA).6