The GI (gastrointestinal) tract may be thought of as one long tube that begins at the mouth and ends at the anus. It includes the mouth, pharynx (throat), esophagus, stomach, small and large intestines, rectum and anus.
The GI tract is lined with a mucous membrane, or mucosa. Like the skin, the mucosa is covered or lined with epithelial tissue and is separated from underlying tissue by the basement membrane, where the proteins that provide structural support and bind the layers of skin/mucosa are located.
When EB is present, one of these proteins is absent or diminished, and the skin/mucosa becomes fragile. When this fragile skin/mucosa is subjected to even minor friction or trauma, the layers separate, fluid seeps into the detached area, and a blister forms.
When EB is present, blisters and erosions may occur in the GI tract. They are most obvious in the mouth and may cause pain, bleeding, and difficulty eating and drinking. When these lesions occur in the small intestines, they interfere with absorption of nutrients. When they occur in the rectum or anus, they may cause bleeding and pain during bowel movements.
As with the skin, the EB type determines whether scarring will develop as the blisters heal. Scarring along the GI tract may result in significant problems, depending on location.