Loss of function, mutation of the human GRN gene, and insufficient haploidy of PGRN may potentially affect PGRN levels, leading to neurodegenerative diseases such as frontotemporal degeneration (FTLD), neuronal ceroid lipofuscinosis, and Alzheimer’s disease (4, 53, 54). Here, GRN is linked to early-onset autosomal dominant Alzheimer disease.