In the acute phase, the levels of AP activation markers C3d (P < 0.001 for STEC-HUS and aHUS), C3bBbP (STEC-HUS: P < 0.01; aHUS: P < 0.001), and C3b/c (STEC-HUS: n.s.; aHUS: P < 0.01) were increased as well, as depicted in Fig. 4e, g, and h. This evidence concerns the gene C3 and hemolytic-uremic syndrome.