The endosome–lysosomal system indeed seems to be a major pathway affected by ageing and AD, with many changed proteins associated with lysosomes, notably proteins involved in lysosomal quality control (LQC) were altered in ageing (for example, CNN2 and HspB1) and AD (for example, DPP7, PLBD2, PLD3 and TAGLN). This evidence concerns the gene DPP7 and Alzheimer disease.