A familial CBS overlap with primary progressive aphasia is more commonly associated with GRN mutations (van Swieten and Heutink 2008), but is nonetheless a rare phenotype of GRN. More recently, case reports of familial CBS caused by C9orf72 and CSF1R have been described, but this is also rare and an unusual phenotype for these genes. The gene discussed is C9orf72; the disease is primary progressive aphasia.