Stxs, the major virulence factors of STEC, are broadly classified into two types: stx1 and stx2. Furthermore, in the Stx1 group, stx1a is found in major STEC strains causing HC and HUS in humans, whereas stx1c and stx1d are rarely associated with human infections. The gene discussed is STX2; the disease is hemolytic-uremic syndrome.