Extensive genetic polymorphism in the human tumor necrosis factor region and relation to extended HLA haplotypes

Abstract

We have identified three polymorphic microsatellites (which we call TNFa, TNFb, and TNFc) within a 12-kilobase region of the human major histocompatibility complex (MHC) that includes the tumor necrosis factor (TNF) locus. TNFc is located within the first intron of the TNF-β gene and has only 2 alleles. TNFa and TNFb are 3.5 kilobases upstream (telomeric) of the TNF-β gene and have at least 13 and 7 alleles, respectively. TNFa, -b, and -c alleles are in linkage disequilibrium with alleles at other loci within the MHC, including class I, class II, and class III. TNFa, -b, and -c alleles are also associated with extended HLA haplotypes. These TNF polymorphisms will allow a thorough genetic analysis of the involvement of TNF in MHC-linked pathologies.