Diagnosing mitochondrial, neurogastrointestinal leukoencephalopathy requires mutations in TYMP1, POLG1, LIG1, or RRM2B

Abstract

Letter to the EditorWith interest we read the article by Jiang et al. about a 23-year-old female with mitochondrial neurogastrointestinal encephalopathy (MNGIE) [1]. The diagnosis MNGIE was established solely on the basis of the clinical presentation without documentation of a causative mutation [1]. Clinical manifestations of the obviously mitochondrial disorder (MID) included nonradiating, postprandial epigastric pain, bilious emesis, weight loss for 3 months, and lower limb weakness for 3 weeks [1]. Workup revealed dissociated sensory disturbances, ophthalmoparesis, gastrointestinal reflux, gastroparesis, demyelinating, sensorimotor neuropathy, myopathy, and extensive leukoencephalopathy [1]. The study is compelling but raises concerns that require further discussion.The main limitation of the study is that the diagnosis "MNGIE" was established without documentation of a causative mutation [1]. There was also no measurement of pyridine or dihydropyridine in the urine. MNGIE is usually associated with pyrimidinuria and