CTSD and Alzheimer disease: Crucial roles of many AD-associated genes in the autophagy-lysosome pathway (ALP), including presenilin 1, cystatin C, cathepsin D, and phospholipase D3 (Lee et al., 2010; Schuur et al., 2011; Hua et al., 2012; Cruchaga et al., 2014) suggest ALP pathway may play a central role in AD pathogenesis.