It also defines up to 50% of FTLD (excluding mutant MAPT (TAU) patients (Irwin et al. 2015) and is apparent in diseases arising from mutations in progranulin (GRN) and C9Orf72, as well as all LATE cases (Nelson et al. 2019), and other diseases such as multiple system proteinopathy, Perry syndrome and inclusion body myositis (IBM) (de Boer et al. 2020). The gene discussed is MAPT; the disease is inclusion body myositis.