Familial AD (FAD) is an early-onset, autosomal dominant disorder, that is associated with mutations in amyloid beta precursor protein (APP), presenilin 1 (PSEN1) and presenilin 2 (PSEN2), and representing less than 5% of all Alzheimer’s disease cases3. The gene discussed is PSEN1; the disease is early-onset autosomal dominant Alzheimer disease.