Apolipoprotein E genotyping in Alzheimer's disease in an Australian sample

Background: Several previous studies have reported an increased frequency of the E4 allele of the gene for Apolipoprotein (APOE4) in both familial and sporadic Alzheimer's disease (AD). We report the results of a study of this association in an Australian clinic-based sample. Aims: To investigate the relationship between APOE4 frequency and AD in an Australian clinic-based sample and compare the results with previous studies. Methods: Subject DNA was PCR amplified, enzymatically digested with Hha1 and the resulting fragments electrophoretically separated. The genotypes were ascertained according to the resulting fragment sizes and the resulting allele frequencies analysed by calculating a z-statistic for comparison of two proportions. Results: The frequency of the APOE allele was 53% in the AD group and 11% in the control group. This difference is statistically significant. There was no significant difference in E4 allele frequencies between AD subjects with a family history and those without. At least one E4 allele was found in 26/30 (87%) of AD patients and 10/50 (20%) of controls. The allele frequencies of the control subjects used in this study were found to be consistent with those of several previous studies. Conclusion: The frequency of the APOE4 allele was significantly higher in AD subjects than in unaffected controls. This provides further evidence of an association between APOE4 and both familial and sporadic AD.