The glycoprotein PGRN, which has been implicated in neurodegenerative diseases such as frontotemporal dementia, lysosomal storage disorders, and neuronal ceroid lipofuscinosis, traffics to lysosomes, where it is processed to GRNs and performs critical functions, including regulating lysosomal pH and degrading proteins and lipids (19, 20). The gene discussed is ART4; the disease is infantile neuronal ceroid lipofuscinosis.