PSEN2 and familial Alzheimer disease: Cases in which AD is diagnosed in later life, beyond the age of 60, are referred to as sporadic AD (SAD), whereas in familial AD (FAD) patients develop AD symptoms at younger ages due to mutations in genes such as amyloid precursor protein (APP), presenilin-1 (PSEN1) and presenilin-2 (PSEN2) [2].