Manning et al. found that clade 8 O157:H7 strains which were significantly more likely to infect patients with HUS and more likely to have both the stx2a and stx2c genes, implying that the carriage of both the Stx2a and Stx2c phages contributes in part to the greater virulence of clade 8 strains [48]. The gene discussed is STX2; the disease is hemolytic-uremic syndrome.