Should the presence of polymorphisms of CYP2C19 enzymes influence the choice of the proton pump inhibitor for treatment of Helicobacter pylori infection? 
There are variations in the CYP2C19 genotypes, that are important for the metabolism of PPIs.  Patients who are heterozygotes for the mutation, but especially homozygotes, have a much slower metabolism, which will result in more profound acid suppression.  Studies have been published, that suggest that the success rate of anti-Helicobacter therapy is in part related to the CYP2C19 genotype of the patient.  However, it is important to keep in mind that most studies that have evaluated this have been carried out in Asia, in particular in Japan, where the prevalence of poor metabolizers (PM) is much higher than, for example, in Caucasians.  The systematic review published in this issue suggests that particularly for omeprazole in combination with amoxicillin or amoxicillin and clarithromycin the success rate is much lower when compared to other proton pump inhibitors (PPIs).  However, there was marked heterogeneity when the results were pooled in formal meta-analysis.  Study quality was suboptimal and other factors such as resistance to antibiotics may explain the observed differences in success rates.  More clinical trial data are needed before we can accept the conclusions of this meta-analysis.