A functional polymorphism of the TNF-α gene that is associated with type 2 DM

To examine the association of the tumor necrosis factor-α (TNF-α) gene region with type 2 diabetes (DM), 11 single-nucleotide polymorphisms (SNPs) of the region were analyzed. The initial study using a sample set (148 cases vs. 227 controls) showed a significant association of the SNP IVS1G + 123A of the TNF-α gene with DM (p = 0.0056). Multiple logistic regression analysis using an enlarged sample set (225 vs. 716) revealed the significant association of the SNP with DM independently of any clinical traits examined (OR: 1.49, p = 0.014). The functional relevance of the SNP were examined by the electrophoretic mobility shift assays using nuclear extracts from the U937 and NIH3T3 cells and luciferase assays in these cells with Simian virus 40 promoter- and TNF-α promoter–reporter gene constructs. The functional analyses showed that YY1 transcription factor bound allele-specifically to the SNP region and, the IVS1 + 123A allele had an increase in luciferase expression compared with the G allele.