title: [Frequency of the APOE-4 allele in Alzheimer's disease and its variation with age in Asturias (Spain)].
abstract: BACKGROUND
  Patients with late-onset Alzheimer's disease show a higher frequency of the APOE-4 than controls. The usefulness of the APOE genotyping in the diagnosis of the disease is controversial. Recently, an age dependent prevalence of APOE-4 in Alzheimer's disease has been described, with a maximum frequency for patients with an age at onset between 65 and 80 years. Additionally, the APOE-4 frequency in healthy controls is similar among the different age-groups, including healthy octogenarians. These data suggest that APOE-4 determines when and not who will develop the disease.
  
  
  METHODS
  The APOE genotype was defined following a previously described PCR-protocol. We analysed 120 patients with clinically defined probable Alzheimer's disease and 250 controls from the same Caucasian population (Austrias, Northern Spain).
  
  
  RESULTS
  We found a significantly higher frequency of the APOE-4 in patients, compared to controls (p = 0.00001). The prevalence of this allele was 65% among patients with an age at onset 66-70, falling to 36% and 18% in patients younger than 65 and older than 80 years, respectively. The average age (SD) at onset did not differ between the E-44 (69 years), E-34 (73 years) and E-33 (73 years). APOE-4 frequency was similar between the different age-groups of controls, including healthy octogenarians.
  
  
  CONCLUSIONS
  In Asturias, APOE genotyping can not be used for the presimptomatic diagnosis of Alzheimer's disease. However, individuals carrying this allele would have a higher probability of developing the disease at an age between 65 and 80 years if they are predisposed (genetically and/or environmentally) to the disease.
authors.affiliation: Laboratorio de Genética Molecular, Instituto Reina Sofía de Estudios Nefrológicos, Hospital Central de Asturias, Oviedo.
authors.forename: V
authors.initials: V
authors.lastname: Alvarez
authors.forename: R
authors.initials: R
authors.lastname: Alvarez
authors.forename: J
authors.initials: J
authors.lastname: Peña
authors.forename: C H
authors.initials: CH
authors.lastname: Lahoz
authors.forename: C
authors.initials: C
authors.lastname: Martínez
authors.forename: L
authors.initials: L
authors.lastname: Menéndez-Guisasola
authors.forename: J
authors.initials: J
authors.lastname: Salas-Puig
authors.forename: G
authors.initials: G
authors.lastname: Morís
authors.forename: D
authors.initials: D
authors.lastname: Uría
authors.forename: B B
authors.initials: BB
authors.lastname: Menes
authors.forename: R
authors.initials: R
authors.lastname: Ribacoba
authors.forename: J A
authors.initials: JA
authors.lastname: Vidal
authors.forename: E
authors.initials: E
authors.lastname: Coto
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000483:Alleles; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics*; D002391:Catchment Area, Health; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D013030:Spain / Q000453:epidemiology
chemical_list: D001057:Apolipoproteins E