These possible medication responses (i.e., toxicity/efficacy issues) are precisely what we would expect to see in patients with actionable phenotypes, such as increased adverse effects in a CYP2C19 poor metabolizer who chronically takes PPIs (e.g., more frequent respiratory infections) or inadequate response to escitalopram in a CYP2C19 ultra-rapid metabolizer. This evidence concerns the gene CYP2C19 and respiratory tract infectious disorder.