Association of apolipoprotein E polymorphism in late-onset Alzheimer's disease and vascular dementia in Brazilians.
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.
Souza
D R S
DR
Departamento de Biologia Molecular, Faculdade de Medicina de São José do Rio Preto, SP, Brasil.
de Godoy
M R
MR
Hotta
J
J
Tajara
E H
EH
Brandão
A C
AC
Pinheiro Júnior
S
S
Tognola
W A
WA
dos Santos
J E
JE
D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D000544:Alzheimer Disease / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics*; D016022:Case-Control Studies; D015140:Dementia, Vascular / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012307:Risk Factors
D001057:Apolipoproteins E