Characterization of CYP2C19*17 Polymorphism in a Portuguese Population Sample Relevant for Proton Pump Inhibitor Therapy—A Pilot Study

The interindividual variability of Proton Pump Inhibitor (PPI) therapy results from the phenotype variability associated with the cytochrome P450 2C19 (CYP2C19) gene, namely the CYP2C19*17 allele. Our aim was to characterize patients’ genetic variability undergoing PPI therapy. A sample of 33 oral mucosa cells from Portuguese pharmacy patients was collected, followed by genotyping. The allelic frequencies of CYP2C19*1 (-806C) and CYP2C19*17 (-806T) were 71.2% and 28.8%, respectively. The genotypic frequencies for CYP2C19*1/*1 and CYP2C19*1/*17 were 42.4% and 57.6%, respectively, and 19 of these patients may have a Rapid Metabolizer (RM) phenotype pharmaceutical opinion letter, based on genetic evidence.