[Frequency of the APOE-4 allele in Alzheimer's disease and its variation with age in Asturias (Spain)].
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.
Alvarez
V
V
Laboratorio de Genética Molecular, Instituto Reina Sofía de Estudios Nefrológicos, Hospital Central de Asturias, Oviedo.
Alvarez
R
R
Peña
J
J
Lahoz
C H
CH
Martínez
C
C
Menéndez-Guisasola
L
L
Salas-Puig
J
J
Morís
G
G
Uría
D
D
Menes
B B
BB
Ribacoba
R
R
Vidal
J A
JA
Coto
E
E
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
D001057:Apolipoproteins E