Mitochondrial enteropathy: The primary pathology may not be within the gastrointestinal tract

Background - Mitochondrial DNA (mtDNA) defects are an important cause of disease. Although gastrointestinal symptoms are common in these patients, their pathogenesis remains uncertain. Aim - To investigate the role of the mtDNA defect in the production of gastrointestinal dysfunction. Patient - A 20 year old woman who presented at 15 years of age with recurrent vomiting and pseudo-obstruction, who did not respond to conservative management and ultimately had subtotal gastrectomy and Roux-en-y reconstruction. She subsequently presented with status epilepticus and was found to have a mitochondrial respiratory chain disorder due to a pathogenic mtDNA point mutation (A3243G). Methods - Resected bowel was studied using light and electron microscopy and mtDNA analysed from both mucosal and muscular layers using polymerase chain reaction generated RFLP analysis. Results - Histological and electron microscopic studies revealed no morphological abnormalities in the resected stomach, and molecular genetic analysis failed to identify the genetic defect in either the mucosal or muscle layers. Conclusion - This study suggests that in some individuals with gastrointestinal symptoms associated with established mitochondrial DNA disease, the primary pathology of the mitochondrial enteropathy lies outside the gastrointestinal tract.