Ng EK et al. found that GSTM1 null genotype was more prevalent in gastric cancer cases with Helicobacter pylori infection than without the infection, and the result suggested that the absence of GST-mu function might have enhanced the susceptibility of these patients to the carcinogenic process initiated or facilitated by Helicobacter pylori [19]. The gene discussed is GSTM1; the disease is gastric cancer.