Inclusion Criteria:

For patients with GERD

- Patients referred for anti-reflux surgery

- On PPI therapy for at least 6 months

- Positive ambulatory pH monitoring (%time pH<4 > 4.7)

- Age greater than 18 years old.

- Both genders

For non-GERD controls

- Negative ambulatory pH monitoring OR

- Upper endoscopy performed for non-GERD symptoms.

- Age greater than 18 years old.

- Both genders

Exclusion Criteria:

- Prior foregut surgery

- Contra-indications for operation (poor clinical status, etc.)

- Contra-indications for endoscopy and biopsy (esophageal or gastric varices,
therapeutic anticoagulation with Coumadin or Heparin, etc.)

- Unwillingness to participate in all of the follow-up studies

- Pregnancy

- Patients using medications that may interfere with PPIs pharmacokinetics (sucralfate,
ketoconazole (Nizoral), ampicillin (Omnipen, Principen), digoxin (Lanoxin,
Lanoxicaps), and iron (Feosol, Mol-Iron, Fergon, Femiron).

- Patients using medications that may interfere with gene expression
(Immunosuppressants, Aspirin, NSAIDs, Corticosteroids).

- Patients with diseases that may interfere with gene expression (autoimmune diseases,
diseases that course with immunosuppression).