GRN and Alzheimer disease: Although CSF sTREM2 does not seem useful for differentiating between individuals with FTD and healthy controls, or for delineating a particular clinical subtype of FTD, levels are higher in familial FTD associated with GRN mutations (albeit within a small preliminary cohort) and in individuals with a clinical syndrome consistent with FTD but underlying AD, rather than FTLD, pathology.