Mutation in the granulin (GRN) gene, resulting in haploinsufficiency of the progranulin (PGRN) protein, is one of the leading causes of frontotemporal lobar degeneration (3, 4, 5), with over 70 disease-associated GRN mutations identified (https://www.uptodate.com/contents/frontotemporal-dementia-epidemiology-pathology-and-pathogenesis). Here, GRN is linked to frontotemporal dementia.