HLA-DRB1 and immunoglobulin G4-related sclerosing disease: Previous studies reported an association of HLA-DRB1 and FCGR2B with IgG4-RD, including with phenotypical characteristics (98), and two studies observed a relation between HLA genes, particularly HLA-DQB1*04:01", HLA-DRB1*04:05 and HLA-DRB1*16 in patients with autoimmune pancreatitis type 1 and 2 (158, 159).