In humans, heterozygous GRN mutations cause frontotemporal dementia (FTD) due to progranulin haploinsufficiency (3, 4) and reduced progranulin levels are a risk factor for Alzheimer’s disease (5, 6, 7, 8, 9, 10, 11). The gene discussed is GRN; the disease is early-onset autosomal dominant Alzheimer disease.