Analyses of CYP2C19 Genotypes For genotype analysis, each patient's peripheral blood leukocytes were obtained and their DNA was extracted. Genotyping procedures that identified the CYP2C19 wild-type allele and the two known mutant alleles, CYP2C19m1 in exon 5 and CYP2C19m2 in exon 4, were carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique with allele-specific primers.[19] On the basis of their ability to metabolize PPI, individuals were classified as extensive metabolizers (homEM: homozygous for wild-type allele), heterozygous extensive metabolizers (hetEM: carrier of only one mutant allele), or poor metabolizers (PM: homozygous for variant allele). All laboratory procedures were performed blind to the patient's randomization status.