Mitochondrial neurogastrointestinal encephalopathy (MNGIE), usually an autosomal-recessive inherited condition, causes gastrointestinal dysmotility, ophthalmoplegia, ptosis, leukoencephalopathy and neuropathy. The chromosome 22 disorder, due to mutations in the nuclear gene TYMP encoding thymidine phosphorylase (TP), leads to the accumulation of thymidine and deoxyuridine, with mitochondrial dysfunction. This report describes a patient with an MNGIE-like syndrome with a heterozygous TYMP mutation who showed marked, but transient improvement postallogeneic haematopoietic stem cell transplantation (HSCT). The patient, showing ptosis and ophthalmoplegia, was initially managed for myasthenia gravis. She developed gastrointestinal symptoms, dysarthria, dysphagia and weakness, and MNGIE was considered due to its low TP levels and improvement after platelet transfusions. She underwent HSCT, with dramatic improvement, but regressed 18 months later despite normal TP levels, platelet counts and full chimerism. MNGIE may encompass a spectrum of disorders. TP deficiency alone is unlikely to explain all clinical signs, and other factors, including the possible development of anti-TP antibodies, which may play a role in the pathophysiology.

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Allogeneic hematopoietic SCT (HSCT) has been proposed as a treatment for patients with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). HSCT has been performed in nine patients using different protocols with varying success. Based on this preliminary experience, participants of the first consensus conference propose a common approach to allogeneic HSCT in MNGIE. Standardization of the transplant protocol and the clinical and biochemical assessments will allow evaluation of the safety and efficacy of HSCT as well as optimization of therapy for patients with MNGIE.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a multisystemic autosomal recessive disease due to primary thymidine phosphorylase (TP) deficiency. To restore TP activity, we performed reduced intensity allogeneic stem cell transplantations (alloSCTs) in two patients. In the first, alloSCT failed to engraft, but the second achieved mixed donor chimerism, which partially restored buffy coat TP activity and lowered plasma nucleosides. Thus, alloSCT can correct biochemical abnormalities in the blood of patients with MNGIE, but clinical efficacy remains unproven.Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease caused by mutations in the ECGF1 gene encoding thymidine phosphorylase (TP). 1-3 The disease is characterized by ophthalmoplegia, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and leukoencephalopathy and typically causes death in early to mid-adulthood. 1,3,4 Laboratory studies reveal defects of the respiratory chain and mitochondrial DNA (mtDNA) alterations. 1,3,4

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