CYP2C19 and gastroesophageal reflux disease: A previous meta-analysis reported significantly different cure rates of PPI therapy in patients with gastroesophageal reflux disease, a major acid-related disease, with different CYP2C19 genotypes (ITT analysis: EMs, 52.2%; IMs, 56.7%; PMs, 61.3%; p = 0.047), and that CYP2C19 EMs had an increased risk of being refractory to PPI therapy compared to PMs (OR: 1.661, 95% CI 1.023–2.659, p = 0.040) (Ichikawa et al., 2016).