1. Barrett's Esophagus Unit, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA;
2. Barrett's Esophagus Unit, Division of Gastroenterology and Hepatology, Mayo Clinic, Scottsdale, Arizona, USA;
3. Barrett's Esophagus Unit, Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, Florida, USA;
4. Department of Pathology, Mayo Clinic, Jacksonville, Florida, USA;
5. Department of Pathology, Mayo Clinic, Scottsdale, Arizona, USA;
6. Department of Pathology, Mayo Clinic, Rochester, Minnesota, USA.