PSEN2 and Alzheimer disease: Alzheimer genetics involves the mutated forms of presenilin 1 (PSEN1), presenilin 2 (PSEN2), Amyloid Precursor Protein (APP), and apolipoprotein E. There are still no permanent treatments available for AD except acetylcholinesterase (AChE) inhibitors which provide only temporary relief (Birks, 2006; Lindvall and Kokaia, 2006).