PSEN1 and familial Alzheimer disease: Autosomal dominant inheritance of mutations in the AMYLOID BETA A4 PRECURSOR PROTEIN gene (APP) [3], PRESENILIN 1 and 2 genes (PSEN1, PSEN2) [4], and SORTILIN-RELATED RECEPTOR gene (SORL1) [5,6] are considered to be the major cause of fAD.