GRN and frontotemporal dementia: Although several groups had reported an exclusive presence of tau-negative, ubiquitin-positive neuronal intranuclear inclusions in a subset of familial FTD patients without identifiable MAPT mutations, and others had narrowed potential candidate region to an area surrounding the MAPT [43-45], it was not until 2006 that GRN mutations were identified in familial FTLD via extensive candidate-gene sequencing [20, 39, 46].