APP and Alzheimer disease: (2) Investigation of the mutations of APP, PSEN1 andPSEN 2, when available, is recommended in cases of AD with a familyhistory consistent with autosomal-dominant inheritance(Standard).(3) Investigation of mutations of APP, PSEN1 and PSEN 2,when available, in asymptomatic individuals with family member(s)who have genetically-confirmed diagnosis of AD should only beindicated after extensive genetic counseling and with the fullconsent of the individual (Practice Option).