We analyzed mRNA expression of RANK and RANKL in normal kidney tissues (n = 3), focal segmental glomerulosclerosis (FSGS, n = 12), IgA nephropathy (n = 14), and membranous nephropathy (MN, n = 16), and the latter three groups are with proteinuria. The gene discussed is TNFSF11; the disease is IgA glomerulonephritis.