Typing of Tumor Necrosis Factor Alleles

The tumor necrosis factor (TNF) locus contains the three closely related cytokine genes: TNF , and lymphotoxin α and �. The gene cluster lies at the telomeric end of the class III region of the major histocompatibility complex (MHC) approximately 1 megabase telomeric to the human leukocyte antigen (HLA)-DR locus and 250 kb centromeric to HLA-B. In view of the potent biological activites of these molecules and the location of their genes within the MHC, the possibility that polymorphism within the TNF locus could influence the onset of, or the outcome from, a large number of autoimmune or infectious diseases, has lead to intensive genetic investigation.