“…DNA typing of HLA-DR alleles from patients with RA confirmed the shared epitope hypothesis, because HLA-DRB1*0401, 0404, 0405, 0408, HLA-DRB1*0101 and DRB1*1402 share the same sequence at positions 70–74 in the third exon, but DRB1*0402 and others do not [7, 14]. HLA antigens have also been reported to be associated with the reactive side effects of drugs to RA [15, 16, 17, 18, 19, 20, 21]and also with the severity of the disease [22, 23, 24, 25, 26, 27, 28, 29, 30]as well as with the susceptibility to RA with extra-articular manifestations [25, 31, 32, 33, 34, 35]. …”