MAPT and frontotemporal dementia: Whereas some FTD mutations, including the R406 mutation, have been reported to cause long-range effects on phosphorylation sites47, most analyses of the consequence of expressing P301L mutant Tau in various cell models indicated no or few differences in phospho-site occupancy48 and hyperphosphorylation of P301L mutant Tau is typically only observed in adult brain tissue49.