A similar difference could be found for HLA-DRB1*04, which is increased in classical AID diabetes mellitus type 1, rheumatoid arthritis and autoimmune hepatitis patients58,65, but decreased in IgG4-AID (MuSK, TTP and CIDP)—with the exception of pemphigus, where a strong association was observed. The gene discussed is HLA-DRB1; the disease is thrombotic thrombocytopenic purpura.