Haploinsufficiency of the progranulin (PGRN) protein, due to heterozygous mutations in the granulin (GRN) gene, is a leading cause of frontotemporal lobar degeneration with TDP‐43 aggregates (FTLD‐TDP) (Baker et al, 2006; Cruts et al, 2006; Gass et al, 2006). This evidence concerns the gene GRN and frontotemporal dementia.