Patients with atypical HUS should, therefore, undergo complement factor determination (C3, factor H, factor I, factor B, and MCP expression), genotyping (factor H, factor H-linked genes, factor I, MCP, factor B and C3) and determination of anti-factor H antibodies prior to renal Tx so that the risk of graft failure can be evaluated [6]. Here, C3 is linked to hemolytic-uremic syndrome.