GRN and frontotemporal dementia: In fact, reduction in PGRN levels resulted in increased lysosomal biogenesis as marked by elevated levels of lysosomal gene expression and protein levels and both cellular models of GRN-FTD as well as heterozygous or homozygous GRN knockout mice present with an accumulation of lysosomes that are unable to mature or fuse properly and have an aberrant proteome [387-392].