CARD9 and primary membranoproliferative glomerulonephritis: In addition, CARD9 staining in renal biopsies with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), diabetic nephropathy (DN), and membranoproliferative glomerulonephritis (MPGN) was negative while that of Henoch–Schonlein purpura nephritis (HSPN) was positive (Figure 5D).