Gastroesophageal reflux (GER) is characterized by the retrograde movement of stomach contents into the esophagus. In its most severe form, GER results in extensive tissue damage caused by acid reflux. In adolescents and adults, and even infrequently in children, chronic GER is associated with the risk of developing Barrett metaplasia (614266), a premalignant lesion of the esophageal mucosa (Hu et al., 2000). In turn, Barrett metaplasia is correlated with the development of adenocarcinoma of the esophagus (see 614266), estimated as the fifth most prevalent neoplasia in the Western world (Lagergren et al., 1999).