Among these diseases, primary and secondary hemolytic uremic syndromes (HUS) are evoked once thrombotic thrombocytopenic purpura (TTP) (a disintegrin and metalloprotease with thrombospondin type I repeats-13 (ADAMTS13) activity <10%), Shiga-toxin HUS (specific stool-or rectal swab culture and shigatoxin polymerase-chain reaction (PCR)), and cobalamin C-related HUS (very high homocysteinemia) are ruled out. This evidence concerns the gene ADAMTS13 and thrombotic thrombocytopenic purpura.