APP and early-onset autosomal dominant Alzheimer disease: The SORL1 (sortilin-related receptor 1) gene encodes a transmembrane protein, named sortilin-related receptor (SORLA), involved in endo-lysosomal processes, amyloid precursor protein (APP) sorting and in the degradation of amyloid-beta (Ab) peptide, responsible for Alzheimer’s disease (AD) pathology [68,69].