Association of apolipoprotein E polymorphism in late-onset Alzheimer's disease and vascular dementia in Brazilians

• Published in: Brazilian journal of medical and biological research Vol. 36; no. 7; pp. 919 - 923
• Main Authors: Souza, D R S, de Godoy, M R, Hotta, J, Tajara, E H, Brandão, A C, Pinheiro Júnior, S, Tognola, W A, dos Santos, J E
• Format: Journal Article
• Language: English; Portuguese
• Published: Brazil Associação Brasileira de Divulgação Científica 01.07.2003
• Subjects: Aged; Aged, 80 and over; Aging; Alleles; Alzheimer Disease - genetics; Alzheimer's disease; Apolipoprotein E; Apolipoproteins E - genetics; BIOLOGY; Case-Control Studies; Dementia; Dementia, Vascular - genetics; Female; Genetic polymorphisms; Genetic Predisposition to Disease; Genotype; Humans; Male; MEDICINE, RESEARCH & EXPERIMENTAL; Polymerase Chain Reaction; Polymorphism, Genetic; Risk Factors; Vascular dementia; Aging; Vascular dementia; Apolipoprotein E; Alzheimer's disease; Genetic polymorphisms; Dementia
• ISSN: 0100-879X; 1414-431X; 1414-431X; 0100-879X
• DOI: 10.1590/S0100-879X2003000700013

The genetic basis for dementias is complex. A common polymorphism in the apolipoprotein E (APOE) gene is considered to be the major risk factor in families with sporadic and late-onset Alzheimer's disease as well as in the general population. The distribution of alleles and genotypes of the APOE gene in late-onset Alzheimer's disease (N = 68), other late-life dementias (N = 39), and in cognitively normal controls (N = 58) was determined, as also was the risk for Alzheimer's disease associated with the epsilon4 allele. Peripheral blood samples were obtained from a total of 165 individuals living in Brazil aged 65-82 years. Genomic DNA was amplified by the polymerase chain reaction and the products were digested with HhaI restriction enzyme. APOE epsilon2 frequency was considerably lower in the Alzheimer's disease group (1%), and the epsilon3 allele and epsilon3/epsilon3 genotype frequencies were higher in the controls (84 and 72%, respectively) as were the epsilon4 allele and epsilon3/epsilon4 genotype frequencies in Alzheimer's disease (25 and 41%, respectively). The higher frequency of the epsilon4 allele in Alzheimer's disease confirmed its role as a risk factor, while epsilon2 provided a weak protection against development of the disease. However, in view of the unexpectedly low frequency of the epsilon4 allele, additional analyses in a more varied Brazilian sample are needed to clarify the real contribution of apolipoprotein E to the development of Alzheimer's disease in this population.