The levels of plasma C3a [(median, IQR) 536.86, 276.59–977.78 vs. 87.40, 55.80–126.31 ng/ml, P<0.001], C5a (9.95, 6.78–16.00 vs. 6.42, 2.68–10.88 ng/ml, P<0.001), and soluble C5b-9 (381.61, 292.02–516.68 vs. 303.98, 240.24–448.45 ng/ml, P = 0.010) were significantly higher in patients with primary FSGS than that in normal controls (Fig 1). This evidence concerns the gene C3 and focal segmental glomerulosclerosis.