Lack of association between interleukin-1alpha polymorphism and Alzheimer disease or vascular dementia.

Recently, a C/T polymorphism in the promoter region of the interleukin 1-alpha (IL-1alpha) gene (position -889) was reported to be associated with Alzheimer disease. In this study, the polymorphism of IL-1alpha was examined in patients with Alzheimer disease, vascular dementia, and nondemented controls in a Chinese population in Taiwan. No difference was found in the IL-1alpha T allele frequency among the three groups. The predominant polymorphic allele ( approximately 90%) of IL-1alpha was the C allele. The APOE4 allele was overrepresented in the AD cohort. The presence of the APOE4 allele did not influence the IL-1alpha genotype or allele distribution. The prevalence of the IL-1alpha T allele, in particular the homozygous form, was lower than in whites and may account for the lack of association between IL-1alpha C/T polymorphism and Alzheimer disease among Chinese in Taiwan. The presence of the heterozygous IL-1alpha T allele cannot be used for distinguishing Alzheimer disease or vascular dementia from controls.