In these latter patients, who are expected to have TDP-43 pathology but not significant tauopathy, [18F]AV-1451 binding was not intense or extensive compared with the distribution of neuroinflammation ([18F]AV-1451 binding in the C9orf72 carriers was less marked than in semantic dementia, which typically has another form of TPD-43 pathology13). The gene discussed is C9orf72; the disease is semantic dementia.