We investigated genetic factors of H. pylori that are reportedly associated with gastroduodenal diseases, including cagA, cagE, vacA (s/m/i), babA, oipA, iceA, and homB, in 100 clinical strains (53 from Hanoi and 47 from Ho Chi Minh), of which 24 and 76 strains were isolated from patients with PU and chronic gastritis, respectively. The gene discussed is DDX53; the disease is chronic gastritis.