Interleukin (IL)-1 is markedly overexpressed in the brains of patients with Alzheimer's disease (AD). We aimed to evaluate the relationship between three polymorphisms of the IL1 gene (IL-1beta promoter -511T/C, IL-1beta exon 5 E1/E2 and IL-1-RA) and late onset AD in Taiwan Chinese. Forty-six late onset AD patients and 103 unrelated, age-matched, healthy controls living in the same area were included. PCR was used to resolve the two IL-1beta polymorphisms and the IL-1Ra intron 2 polymorphism. The -511T/T type of the IL-1beta promoter (unlike IL-1beta exon 5 and IL-1-RA) was more frequently found in AD than in healthy patients (-511C/C type versus T/T type, OR = 0.944, CI = 0.393, 2.269, P = 0.898; -511C/T type versus T/T type, OR = 0.375, CI = 0.156, 0.902, P = 0.028). The -511T/T genotype (unlike the other two polymorphisms) is a marker demonstrating that late onset AD in Chinese patients in Taiwan is genetically determined.

A large number of epidemiological studies have been performed to investigate the association between Alzheimer's disease (AD) risk and interleukin-1β -511C/T genetic polymorphism, however, inconsistent results have been reported. The effect of the IL-1β -511C/T polymorphism on AD susceptibility was evaluated by a meta-analysis. Series of databases were researched. 14 studies involving 2640 AD case and 3493 control subjects were identified. The pooled results showed there were no statistical associations of interleukin-1β -511C/T genetic polymorphism with susceptibility to AD for five analysis models in all subjects. However, obvious heterogeneity among studies was detected. When stratifying for age at onset, ethnicity and geographic distribution of population to explore the original source of heterogeneity, the meta-analysis results based on geographic distribution of population showed the significant difference (CC vs CT, OR 1.26, 95 % CI: 1.03, 1.54, z = 2.25, P = 0.025; CC vs CT+TT, OR 1.24, 95 % CI: 1.03, 1.50, z = 2.24, P = 0.025) only in non-Europe. These findings indicate that the IL-1β -511C/T polymorphism might be associated with AD risk, and individuals with IL-1β -511C/C genotype might be at higher risk of AD in non-Europe. Further larger sample research would be warranted to confirm these conclusions.