Monomeric Aβ, a cleavage product of the proteolytic processing of the amyloid protein precursor (APP) by a β- and a γ-secretase, aggregates into Aβ oligomers and finally into amyloid fibrils, which are found in AD plaques and were previously considered to be the cause of cognitive deficits [8]. The gene discussed is APP; the disease is Cognitive impairment.