Based on our selection criteria, this study does not provide information about the percentage of APOE genotypes in cognitively unimpaired persons with neuropathological or biomarker evidence of preclinical AD, the percentage of persons who met criteria for MCI with or without neuropathological or biomarker evidence of AD, or the percentage of persons with a primary diagnosis of other neurodegenerative disorders. The gene discussed is APOE; the disease is Alzheimer disease.