Expression and genetic analysis of tumor necrosis factor-α (TNF-α) G-308A polymorphism in sporadic Alzheimer's disease in a Southern China population

Abstract

Alzheimer's disease (AD) is one of most common chronic neurodegenerative diseases in the elderly. Tumor necrosis factor-α (TNF-α) was found elevated markedly in the serum and the cerebral spinal fluid of AD patients. And the elevation of TNF-α was thought to be associated with the occurrence of AD in China. However, it is still unclear whether the TNF-α polymorphism is related to the sporadic Alzheimer's disease (SAD) in China as well. Hence, in this study, we try to investigate the relationship between TNF-α G-308A polymorphism and its susceptibility to SAD in a Southern China population. The polymerase chain reaction-sequence specific primers (PCR-SSP) was performed to detect the frequencies of genotypes and alleles of TNF-α in 112 SAD patients and 121 controls. And the levels of TNF-α in serum were measured by radioimmunoassay. The differences of polymorphic distribution and the levels of TNF-α in serum between groups were then analyzed, and odds ratio was computed for association analysis. The frequency of A-allele was significantly increased in patients with SAD compared with that of the controls (χ2=4.256, P=0.039). A significantly increased risk of SAD was observed in the carriers of A-allele (OR=2.635, 95% CI 1.027–6.763, P<0.01). In parallel, the serum level of TNF-α in SAD group was much higher than that in control group (χ2=10.21, P=0.0042). And the elevation of serum level of TNF-α was closely associated with the risk of SAD (OR=3.542, 95% CI 2.304–8.854, P<0.05) as well. These results suggested that the TNF-α gene G-308A polymorphism might be a risk factor for SAD in Southern China. A-allele might play a role in the susceptibility of SAD.