Previous studies have pointed out various types of AD pathophysiology such as cerebrospinal fluid levels of amyloid-β (Aβ) [32] and other clinical presentations such as cognitive impairments with executive dysfunction and disorientation, language impairment, and memory loss in patients with mutations of either APP, PSEN1, or PSEN2 genes. The gene discussed is PSEN2; the disease is Alzheimer disease.