C4A and hereditary angioedema: Results of laboratory tests demonstrated that the HAE group had a higher level of VEGF (112 [72–169] vs. 60 [39–80] ng/ml, P < 0.001, Fig. 2A) but lower levels of C1-INH (C1-INH/lower normal limit, 0.24 [0.19–0.29] vs. 1.33 [1.19–1.52], P < 0.001) and C4 (0.053 [0.023–0.085] vs. 0.215 [0.178–0.269] mg/ml, P < 0.001).