Serum PGRN level can be elevated in several pathological conditions including hypoxia, acidosis, aging, obesity, acute renal failure, or neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, frontotemporal dementia, or amyotrophic lateral sclerosis [40,41,42,43]. Here, GRN is linked to early-onset autosomal dominant Alzheimer disease.