["Maintenance therapy of gastroesophageal reflux disease (GERD) is usually performed with a low dose of a proton-pump inhibitor (PPI). Because PPIs are metabolized by CYP2C19 in the liver, we investigated whether a patient's CYP2C19 genotype was associated with symptomatic recurrence of GERD during maintenance therapy with a low dose of a PPI.", 'We enrolled 124 patients with erosive GERD whose esophageal mucosal breaks were endoscopically proven to be cured after treatment with lansoprazole 30 mg/day for 8 weeks. When reflux symptoms occurred less than once per week, the dose of lansoprazole was decreased to 15 mg/day, but if symptoms then occurred more than once per week, it was restored to 30 mg/day. CYP2C19 genotypes were classified as rapid metabolizer (RM), intermediate metabolizer (IM) or poor metabolizer (PM).', 'In 18 of 54 RMs, 28 of 56 IMs, and 8 of 14 PMs, the maintenance dose of lansoprazole was decreased to 15 mg/day, but in 16 (88.9%), 22 (78.6%), and 4 (50%), respectively, there was symptomatic recurrence of GERD and the dose was restored to 30 mg/day. The hazard ratios of symptomatic recurrence of GERD in IMs and PMs compared with RMs were 0.40 (95%CI: 0.19-0.87, P = 0.021) and 0.19 (95%CI: 0.05-0.69, P = 0.011).'] Is cYP2C19 genotype associated with symptomatic recurrence of GERD during maintenance therapy with low-dose lansoprazole?