A case of duplication of region 15q11.2q13.1, which is associated with 15q11q13 microduplication syndrome disease, with clinical phenotypes including autism, mental retardation, epileptic seizures, and psychiatric disorders, and occasional structural abnormalities of either of the heart and great vessels.[17] A case of 21q21.2q22.13 segmental duplication compounding 21q21.1 and 21q22.3 deletions covering the APP gene, which is associated with dominantly inherited early-onset Alzheimer disease. The gene discussed is APP; the disease is early-onset autosomal dominant Alzheimer disease.