MAPT and frontotemporal dementia: In FTD cases associated with pathogenic mutations in MAPT, the Tau accumulation in neurons and glia has been explained in terms of abnormal phosphorylation of the protein, or an altered proportion in the production ratio of the 4R and 3R Tau isoforms6; conversely, GRN mutation haploinsufficiency and C9orf72 expansion lead to TDP43 aggregation, with a less defined mechanism7,8.