CYP2C19 Genotype Predictor of Gastric Acid Suppression

Patients with LA Grade B-D erosive esophagitis identified at the time of endoscopy will be prospectively recruited. Patients will undergo whole blood testing for CYP2C19 genotype and will be started on omeprazole 40 mg once daily in the morning 30 minutes before breakfast. The Mayo Dysphasia Questionnaire -30 day (MDQ-30day) will be used during the study. At the end of 8 weeks, patients will undergo dual probe pH/impedance testing on therapy and a clinically indicated endoscopy to rule out Barrett's esophagus and assess healing. CYP2C19 genotyping will be performed in the Mayo laboratory.