The TNF2 allele is a risk factor to severe aplastic anemia independent of HLA-DR.

Severe aplastic anemia (SAA) is a disease with an autoimmune component. The susceptibility to the development of SAA is strongly associated with genes in the major histocompatibility complex (MHC). The gene for tumor necrosis factor-alpha (TNF-alpha) is encoded in the MHC locus and TNF-alpha is involved in the pathogenesis of SAA. A TNF-alpha variant with a polymorphism at position -308 in its promoter region (-308A), which is designated TNF2, has been demonstrated to be linked to a number of autoimmune diseases. In this study, the TNF-alpha -308 promoter polymorphism and HLA-DRB1 alleles were analyzed in 75 SAA patients, 55 mild aplastic anemia patients (MAA), and 128 controls. In SAA the phenotype frequencies of TNF2, HLA-DR3, and -DR2 were significantly higher in comparison to controls. Stratification analysis confirmed that the TNF2 allele contributes to the susceptibility to SAA independently of HLA-DR3 or -DR2. The results indicated that TNF2 might act as an independent risk factor for SAA.