Mitochondrial Respiratory Chain Complex I Deficiency Causes Intractable Gastrointestinal Symptoms

We report the case of a 13-month-old girl who suffered frequent vomiting, intractable diarrhea, hyperlactatemia, and liver dysfunction. Although the symptoms were treatment-resistant, administration of an enteral nutrition formula containing medium-chain triglycerides reduced her weight loss, vomiting, and diarrhea. Immunostaining of mitochondrial respiratory chain (MRC) complexes of her colonic mucosa confirmed the diagnosis of MRC complex I deficiency. This case shows that this disease should be included in the differential diagnosis in patients with hyperlactatemia and intractable, cryptogenic gastrointestinal symptoms. In addition, the mucosa of the affected gastrointestinal organ should be analyzed with immunostaining or electron microscopy for MRC complexes.