Apart from the common late-onset forms of sporadic AD (sAD), rare mutations in the genes encoding the β-amyloid precursor protein (APP; chromosome 21q21), presenilin-1 (PSEN1; chromosome 14q24.3) and presenilin-2 (PSEN2; chromosome 1q31-q42) cause autosomal dominant AD (ADAD; also named as familial AD or FAD) [1]. Here, PSEN2 is linked to familial Alzheimer disease.