SORL1 and early-onset autosomal dominant Alzheimer disease: Dysregulated protein secretion and shedding are linked to neurologic and psychiatric diseases, including neurodegeneration, e.g., APP, APOE, SORL1, and TREM2 in Alzheimer's disease (AD), or the prion protein (PRNP) in prion disease (Lichtenthaler et al, 2018).