Mitochondrial Neurogastrointestinal Encephalopathy: A Case Report from Northeast of Iran.

Mitochondrial neurogastrointestinal encephalopathy (MNGIE) is a rare autosomal recessive disorder often misdiagnosed due to its heterogeneous presentation. We describe a 21-year-old man with a long history of episodic nausea and vomiting, weight loss, and intermittent diarrhea since childhood, initially misdiagnosed as Crohn's disease following a colonoscopy-induced perforation. Despite treatment with adalimumab, his gastrointestinal symptoms persisted. Subsequent investigations revealed dilated stomach and duodenum, and new neurological findings (ptosis, nasal speech) prompted further evaluation. Brain magnetic resonance imaging (MRI) showed leukoencephalopathy, leading to the definitive diagnosis of MNGIE. This case highlights the importance of considering mitochondrial disorders in young patients with refractory gastrointestinal dysmotility and concomitant neurological features to prevent diagnostic delays and unnecessary interventions.