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

• Main Authors: D.R.S. Souza, M.R. De Godoy, J. Hotta, E.H. Tajara, A.C. Brandão, S. Pinheiro Júnior, W.A. Tognola, J.E. Dos Santos
• Format: Article
• Language: English
• Published: Associação Brasileira de Divulgação Científica 2003-07-01
• Series: Brazilian Journal of Medical and Biological Research
• Subjects: Alzheimer's disease; Vascular dementia; Dementia; Apolipoprotein E; Aging; Genetic polymorphisms
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003000700013
• ISSN: 0100-879X; 1414-431X

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.