Isolated deficient alpha6beta4 integrin expression in the gut associated with intractable diarrhea.
An infant born with pyloric atresia had development of intractable diarrhea and was found to have total epithelial detachment of gastric and small and large bowel mucosa. She had no skin abnormalities. Parental consanguinity and pyloric atresia in a sibling who died without autopsy suggest an inherited origin for this disorder. The purpose of this study was to examine defects in intestinal and skin cell adhesion. Histologic, immunohistochemical, and ultrastructural characteristics of the skin and gut of the patient were compared with that of normal control subjects. Distribution of adhesion molecules was determined. Immunofluorescent analysis of the digestive mucosa showed alpha6beta4 integrin expression deficiency at the epithelial cell-lamina propria junction. Ultrastructural examination of the digestive mucosa revealed a complete epithelial detachment with a cleavage plane lying between the lamina densa and the basal pole of the enterocytes. Consistent with the absence of skin blistering, integrin alpha6beta4 was expressed at the dermal-epidermal junction. Electron micrographs of skin biopsy specimens showed the presence of normal hemidesmosomes and the absence of dermal-epidermal dysadhesion. It was postulated that this patient had protracted diarrhea related to epithelial detachment of the digestive mucosa as a consequence of a deficiency of an integrin alpha6beta4 isoform specific to the gut.