Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 44 2 2006 04 15 151 154 P. Ayatollahi A. Tarazi S. Nafissi 2015 09 28 Mitochondrial neurogastrointestinal encephalo-myopathy (MNGIE) is a rare autosomal recessive disease caused by thymidine phosphorylase (TP) gene mutation. Here we report a patient with MNGIE in whom sensorimotor polyneuropathy was the first presenting symptom and had a fluctuating course. This 26-year-old female patient developed acute-onset demyelinating polyneuropathy from the age of 6 with two relapses later on. In addition, she had gastrointestinal symptoms (diarrhea, recurrent abdominal pain), progressive weight loss and ophthalmoparesis. Brain magnetic resonance imaging showed white matter abnormalities, and muscle biopsy showed ragged red fibers. This constellation of clinical and laboratory findings raised the diagnosis of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). This report highlights the uncommon clinical characteristics of this rare disease. https://acta.tums.ac.ir/index.php/acta/article/view/3158 https://acta.tums.ac.ir/index.php/acta/article/download/3158/3138