These studies include investigations describing a weak association of a SNP at position − 308 of the tumor necrosis factor promoter and RA [40, 41], and reports linking the presence of the SE alleles HLA-DRB1*01:01, HLA-DRB1*04:01, HLA-DRB1*04:04, HLA-DRB1*10:01 [22, 23] and HLA-DRB1*04:08 [23], in addition to the non-SE allele group HLA-DR9, to increased disease RA risk [23, 42]. Here, TNF is linked to rheumatoid arthritis.