GRN and Alzheimer disease: Despite this increase, a marked reduction of neuronal PSAP (Fig. 7a–c), saposin A (Supplementary Fig. 6a), saposin B (Fig. 8) and saposin C (Supplementary Fig. 6b) signals is observed in FTLD-GRN compared with controls or AD, supporting our hypothesis that PGRN mutations lead to reduced neuronal saposin levels in FTLD.