C9orf72 and major depressive disorder: Depression is commonly observed across the FTD subtypes with reported frequency of around 30–40% (e.g., C9orf72+: 37.9% versus GRN+: 47.1% in Benussi and colleagues).17,58,59 While the NPI-Q affective subsyndrome and the ISPC Distressed subdomain included depression items, they were not significantly different among the groups.