MRC1 protein, strongly downregulated in IMN vs. PN serum is indeed able by itself to recognise 14 IMN patients over the total of 15 of our dataset, also including 5 PN clusterised with IMN in this step (2 IgAN, 1 FGS, 1 MCD/FSGS and 1 MPGN). Here, MRC1 is linked to primary membranoproliferative glomerulonephritis.