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Apolipoprotein E genotype in Spanish patients of Alzheimer's or Parkinson's disease
D Ibarreta1, T Gómez-Isla, A Portera-Sánchez
1Department of Human Physiology and Molecular Genetics, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
Insights
The apolipoprotein E (APOE) allele epsilon 4 is more common in late-onset Alzheimer's disease patients, potentially indicating an earlier onset of dementia. This allele was not linked to early-onset Alzheimer's or Parkinson's disease.
Area of Science:
- Neurogenetics
- Human Genetics
- Molecular Biology
Background:
- Apolipoprotein E (APOE) genotype, particularly the epsilon 4 allele, is a known risk factor for Alzheimer's disease.
- Previous studies indicate varying frequencies of APOE alleles across different ethnic populations.
- Understanding APOE epsilon 4 distribution is crucial for assessing genetic predisposition to neurodegenerative diseases.
Purpose of the Study:
- To investigate the frequency of the apolipoprotein E (APOE) epsilon 4 allele in blood donors and specific patient groups in the Madrid area.
- To compare APOE epsilon 4 allele frequencies with those reported in other Caucasian populations.
- To explore the association between APOE epsilon 4 and the age of onset in late-onset Alzheimer's disease (AD).
Main Methods:
- Genotyping of apolipoprotein E alleles in blood donors from the Madrid area.
- Analysis of APOE epsilon 4 allele frequency in healthy individuals over 60 years old.
- Comparison of APOE allele frequencies between healthy individuals, late-onset AD patients, early-onset AD patients, and Parkinson's disease patients.
Main Results:
- The frequency of the APOE epsilon 4 allele in Madrid blood donors (6%) is lower than in other Caucasian populations.
- A significantly higher frequency (34%) of the APOE epsilon 4 allele was observed in patients with late-onset Alzheimer's disease.
- Patients with late-onset Alzheimer's disease carrying the epsilon 4 allele exhibited an earlier age of dementia onset.
- No increased frequency of APOE epsilon 4 was found in early-onset Alzheimer's disease or Parkinson's disease patients compared to controls.
Conclusions:
- The APOE epsilon 4 allele is associated with an increased risk and earlier onset of late-onset Alzheimer's disease in the studied Madrid population.
- The lower overall frequency of APOE epsilon 4 in Madrid blood donors suggests potential regional genetic variations.
- APOE epsilon 4 does not appear to be a significant risk factor for early-onset Alzheimer's disease or Parkinson's disease.
Abstract:
Blood donors of the Madrid area show a 6% frequency of apolipoprotein E genotype carrying allele epsilon 4. This frequency is smaller than other populations of Caucasian origin. This proportion decreases to 4% in a selected sample of healthy individuals of ages > 60 years. The frequency (34%) of the allele epsilon 4 was significantly increased in patients of late onset Alzheimer's disease, similarly to other populations. An earlier age of onset of the dementia is observed in the patients of late-onset Alzheimer's disease carrying the allele epsilon 4. No increased frequency in allele epsilon 4 frequency was found in patients of early-onset Alzheimer's disease. Patients of Parkinson's disease do not show any differences in the frequency of the alleles of apolipoprotein E when compared with healthy individuals.