These observations were independently validated in fibroblasts and induced pluripotent stem cell (iPSC)-derived cortical neurons from patients with frontotemporal dementia (FTD, carry heterozygous mutations in PGRN/CLN11), thus highlighting the conserved effect of PGRN/CLN11 on CTSD/CLN10 activity in multiple models [80, 92]. Here, CTSD is linked to frontotemporal dementia.