When we talk about mitochondrial diseases, we refer to the most ubiquitous of metabolic disorders, with pathogenic mitochondrial DNA mutation being found in at least 1 in 8000 individuals.The following statement reveals very vividly, the true nature of mitochondrial disease, “Mitochondrial disease may cause any symptom in any tissue at any age by any inheritance (A. Munics).In view of the presence of mitochondria which are essential organelles of nearly all cells, with the exception of mature erythrocyte. Mitochondrial diseases may affect any organ system and for this reason are now called “Mitochondrial cytopathies”.

Mitochondrial neurogastrointestinal encephalomyopathy is an autosomal recessive disorder in which a nuclear mutation of the thymidine phosphorylase gene leads to mitochondrial genomic dysfunction. Herein, we report a 29-year-old Iranian man with abdominal pain, diarrhea, hearing loss, ophthalmoplegia, sensorimotor axonal neuropathy, and elevated muscle enzymes. Magnetic resonance imaging showed leukoencephalopathic changes. Metabolite analysis revealed a very high thymidine concentration in the patient's urine consistent with the diagnosis of mitochondrial neurogastrointestinal encephalomyopathy.