In CS1, the serological disease type of the 362 RPGN cases registered in the personal clinical records database for the designated intractable diseases RPGN (No. 220) and anti-GBM antibody nephritis (No. 221) included 200 MPO-ANCA-positive cases, 98 anti-GBM antibody-positive cases, 9 PR3-ANCA-positive cases, 8 cases positive for both MPO-ANCA and anti-GBM antibody, 3 cases positive for both PR3- and MPO-ANCA, and 37 others (Fig. 1). Here, MPO is linked to rapidly progressive glomerulonephritis.