No association between the -1031 polymorphism in the TNF-alpha promoter region and type 1 diabetes

Tumor necrosis factor alpha (TNF-alpha) is an important immunomodulator and is believed to be involved in the development or progression of type 1 diabetes. In the following study, we evaluated TNF-alpha promoter polymorphisms at positions -863 and -1031 and their association with type 1 diabetes in a group of 210 diabetic patients from Lebanon. Our results show that in our population, the C allele is predominant at position -863, whereas the A allele is very rare (2%). At position -1031, however, the C and T allele distribution was similar in both the patient (17.8% vs 82.2%, respectively) and the control (21.4% vs 79.6%) groups. No association of TNF-alpha genotype at position 1031 with type 1 diabetes was found as demonstrated by the family-based association test and the transmission disequilibrium test. However, when patient genotypes were compared, the recessive CC genotype was only found in type 1 diabetic males but not in type 1 diabetic females. This observation, however, requires further investigation in a larger sample before conclusive association to gender is suggested. In conclusion, our results demonstrate that no association between TNF-alpha polymorphism and type 1 diabetes seems to exist in our population.