GRN and frontotemporal dementia: Sortilin is also a genetic risk factor for frontotemporal dementia (FTD) (11), and a sorting receptor for progranulin (PGRN) (12, 13, 14), a major causal gene for inherited FTD (15, 16), thus emphasizing a central role for sortilin in the molecular mechanisms underlying conditions associated with dementia (17, 18).