In the study, major genetic factors for EOAD (such as APP, FKBP1B, PSEN1, and PSEN2) and LOPD (such as APOE, CLU, SORL1, PICALM, and BIN1 [9,10,11,12,51]) did not show significantly different expressions in the patients with severe OSA without evident AD. The gene discussed is PSEN2; the disease is Alzheimer disease.