Objective: To verify the association between APOE gene promoter polymorphisms and the development of AD and to determine whether the effect of promoter polymorphisms on AD is independent of the APOE epsilon4 allele.
Background: Three polymorphisms in the APOE promoter have been shown to modify APOE expression in vitro. Several studies have suggested that these polymorphisms may also modulate risk for AD, either independently or by modifying the effect of the APOE coding polymorphism.
Methods: The authors analyzed allele and genotype distributions for APOE and all three known APOE promoter polymorphisms (-491 A/T, -427 T/C, and -219 G/T) in a study group consisting of 237 subjects with AD and 274 age-matched controls. They then used log-linear and logistic regression analyses to test for possible interactions between APOE genotype and the promoter polymorphisms on risk of AD.
Conclusion: A strong association between the APOE epsilon 4 allele and AD was detected regardless of promoter polymorphism status. In addition, the -491 AA genotype appears to be an independent genetic risk factor for AD. The -427 T/C polymorphism and the -219 T/G polymorphism were not directly associated with AD.