3. Summary of Procedures: (i) symptom assessment by chest pain questionnaire; (ii) esophageal reflux evaluation by review of records of 24-hour pH monitoring; (iii) evidence of esophagitis by endoscopy; (iv) esophageal biopsy by endoscopy; (v) mast cell activation study in biopsy specimen by mast cell count, tryptase and Transient receptor potential vanniloid-1 (TRPV1) staining, and histamine release assay.