The Th1/E47cs-G apolipoprotein E (APOE) promoter allele is a risk factor for Alzheimer disease of very later onset.

Several polymorphisms in the apolipoprotein E (APOE) promoter region have been recently described. Of interest, APOE gene expression is increased in association with the -491AT polymorphism T-allele and decreased in relation to the Th1/E47cs polymorphism G-allele. In the present study we have investigated both polymorphisms in a series of 183 Alzheimer disease (AD) patients and 169 controls divided into age at onset/age dependent subgroups and the data obtained have been corrected for the presence of both expression-changing alleles in APOE homozygous individuals. Subsequently, the associations among APOE promoter polymorphisms, APOE4, and AD were assessed by chi-square and logistic regression analyses. Significantly, patients whose age at onset of AD was 80 years or more showed an association between the Th1/E47cs-G allele and AD that was independent of the APOE4 allele.