CYP2C19 and duodenal ulcer: In a previous study, the cure rate of peptic or duodenal ulcers for Japanese patients that received dual therapy with omeprazole (20 mg/day for 2 weeks) and amoxicillin (2,000 mg/day for 2 weeks) was 100% in CYP2C19 PMs, 60% for those who were heterozygous for one mutant allele, and 29% in individuals homozygous for the CYP2C19*1 allele (Furuta et al., 1998).