For example, it is reported that familial AD typically has an earlier age of onset, often under the age of 65, and mainly due to the mutations of PSEN1, PSEN2, and APP (1%–2% of total AD) (Wu, Rosa‐Neto, Hsiung, Sadovnick, & Masellis, 2012). The gene discussed is PSEN2; the disease is Alzheimer disease.