Interleukin 1 Alpha Gene Polymorphism as a Susceptibility Factor in Alzheimer’s Disease and Its Influence on the Extent of Histopathological Hallmark Lesions of Alzheimer’s Disease

We investigated the association of the interleukin 1α (IL1A) (–889) C/T polymorphism with Alzheimer’s disease (AD) and with the extent of AD histopathological lesions, the senile/neuritic plaques (SPs/NPs) and neurofibrillary tangles. We evaluated 98 neuropathologically confirmed AD patients and 240 controls as well as 146 clinically diagnosed AD patients and 278 controls but found no association of the IL1A C/T polymorphism with AD even after adjustment for the apolipoprotein E (APOE) genotype, gender or age. The extents of AD histopathological lesions were not influenced by the IL1A genotype except after exclusion of the APOE Ε4 allele, when a trend towards more SPs/NPs was observed in AD patients with the IL1A C/C compared to patients with the T/T genotype. These results do not confirm previous studies which have indicated that the IL1A C/T polymorphism is a susceptibility factor for AD. However, the IL1A C/C genotype might be associated with the progression of SPs/NPs in AD patients, but the effect is weak and obscured by the APOE Ε4 allele.