Autosomal dominant Alzheimer's disease (ADAD) is a rare form of Alzheimer's disease (AD) that arises from mutations in the genes encoding presenilin 1 (PSEN1), presenilin 2 (PSEN2), or amyloid precursor protein (APP), all affecting APP processing.1 Here, PSEN1 is linked to early-onset autosomal dominant Alzheimer disease.