Functional performance in late-onset GM2 gangliosidosis (Tay-Sachs and Sandhoff diseases), longitudinal data over 3 consecutive years

Anatomically, the normal state in the human adult is an esophagus that is entirely tubular and has a sharp transition to the saccular stomach where it forms an acute angle of His. Histologically, the normal esophagus is lined entirely by stratified squamous epithelium, transitioning at the gastroesophageal junction to gastric oxyntic epithelium, which lines the entire proximal stomach. Cardiac epithelium is normally absent. Its presence indicates the abnormal state of the dilated distal esophagus that results from damage to the abdominal segment of the lower esophageal sphincter. It is the early stage of gastroesophageal reflux disease (GERD) that is presently ignored and mistaken as normal proximal stomach. This normal state is not recognized at present time by the myth that 1–4 mm of cardiac epithelium normally exists between the distal end of the squamous epithelium and the proximal limit of gastric oxyntic epithelium. Evidence that eradicates this myth includes the facts: (1) The cardiac epithelium is absent in some people. (2) The presence of cardiac epithelium in the dilated distal esophagus is associated with the presence of submucosal esophageal glands. (3) Its extent varies from 0 to <15 mm in persons without GERD and increases up to 30 mm in patients with GERD. (4) The presence of any cardiac epithelium is associated with abnormal acid exposure, reflux esophagitis, and manometric abnormalities in the lower esophageal sphincter. (5) Cardiac epithelium extends into the thoracic esophagus as visible columnar-lined esophagus (CLE) in patients with severe GERD associated with severe lower esophageal sphincter damage. (6) The morphologic, immunohistochemical, and molecular features of cardiac epithelium in the dilated distal esophagus and visible CLE are identical and different than those of distal gastric epithelium. Eradication of the myth that cardiac epithelium is normally absent is essential to the understanding of the pathologic changes associated with the earliest stage of GERD. Existence of the myth at present prevents this understanding.