Mitochondrial Neurogastrointestinal Encephalomyopathy Treated with Stem Cell Transplantation: A Case Report and Review of Literature.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disorder. The mutation in the ECGF1 gene causes severe deficiency of thymidine phosphorylase (TP), which in turn increases thymidine and deoxyuridine in the blood, serum, and tissue. The toxic levels of these products cause malfunction of the mitochondrial respiratory chain and mitochondrial DNA. Commonly, patients become symptomatic between 15 and 20 years of age (range 5 months to 35 years). The most commonly affected systems are gastrointestinal, followed by ocular, and nervous system. The disease is often fatal; high mortality rate is reported between 20 and 40 years of age. Treatment modalities that can increase thymidine phosphorylase activity and decrease thymidine and deoxy-uridine have shown symptomatic improvements in patients with MNGIE. Platelet transfusion, hemodialysis, peritoneal dialysis or allogeneic hematopoietic stem cell transplantation (HSCT) have been tried. The survival and long-term benefits of these measures are still not clear. Engrafted patients after stem cell transplantation have showed improvements in serum thymidine and deoxyuridine. We are reporting a case of MNGIE from Saudi Arabia, who underwent allogeneic hematopoietic stem cell transplantation. No MNGIE case has been previously reported from Saudi Arabia or the Gulf Arab countries. From the available literature, so far only 11 patients with MNGIE have undergone stem cell transplantation.

Serum FGF21 levels in adult m.3243A>G carriers: clinical implications.

OBJECTIVES: To determine the value of fibroblast growth factor 21 (FGF21), a recently discovered biomarker for mitochondrial disease, in predicting clinical disease severity and disease progression in adult carriers of the m.3243A>G mutation. METHODS: In the context of a national inventory, the heteroplasmy levels of the m.3243A>G mutation were measured in leukocytes and urinary epithelial cells. The Newcastle Mitochondrial Disease Adult Scale score was determined and blood was drawn for measuring FGF21 concentration. Twenty-five of the included initial patients studied were then selected randomly for a follow-up study. RESULTS: This prognostic study included 99 adult carriers of the m.3243A>G mutation. Our analysis revealed a moderate, significant correlation between FGF21 concentration and disease severity (r = 0.49; p = <0.001). No significant correlations were found between disease severity and the heteroplasmy percentage determined in urinary epithelial cells or the heteroplasmy percentage determined in leukocytes. Weak but significant correlations were also found between FGF21 concentration and the severity of the myopathy (r = 0.38; p = <0.001) and between the concentration of FGF21 and the severity of the encephalopathy (r = 0.30; p = <0.001). Repeated measurements following 25 subjects for 2 years revealed no significant correlation between FGF21 concentration and disease progression. CONCLUSIONS: Measuring FGF21 concentration had little added value in monitoring and predicting the disease course in this specific patient group.

HPLC-UV analysis of thymidine and deoxyuridine in plasma of patients with thymidine phosphorylase deficiency.

We present a simple, fast and validated method for the determination of the two nucleosides thymidine (dThd) and deoxyuridine (dUrd) in plasma of patients with symptoms suggestive of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), using high performance liquid chromatography coupled with ultraviolet spectrophotometric detection (HPLC-UV). Plasma sample (100µL) pretreatment was based on simple deproteinization by 1.2M perchloric acid, using theophylline as internal standard (I.S.). HPLC-UV analysis was carried out on a Synergi 4µm Hydro-RP, 150×4mm I.D. column, at room temperature. The mobile phase was a mixture of potassium dihydrogen phosphate buffer (20mM, pH 4.5) and acetonitrile (95:5, v/v), at an isocratic flow rate of 0.7mL/min. The UV detector was set at 267nm. The chromatographic run lasted 19min. Similar pyrimidine nucleotides and nucleosides do not interfere with the assay. Calibration curves were linear for both dThd and dUrd over a range of 0.5 to 5.0µg/mL. The limit of quantitation was 0.5µg/mL for both nucleosides and the absolute recovery was >90% for dThd, dUrd and the I.S. Both intra- and inter-assay precision and accuracy were lower than 10% at all tested concentrations. The proposed method was successfully applied to measure plasma concentrations of dThd and dUrd in two MNGIE patients. This assay simplifies both plasma pretreatment and chromatographic conditions of previously reported procedures and describes the first validated method for the determination of the two nucleotides in human plasma.

Glutathione: a redox signature in monitoring EPI-743 therapy in children with mitochondrial encephalomyopathies.

BACKGROUND: Genetically defined Leigh syndrome (LS) is a rare, fatal inherited neurodegenerative disorder that predominantly affects children. Although mitochondrial dysfunction has clearly been associated with oxidative stress, few studies have specifically examined Leigh syndrome patients' blood glutathione levels. In this study, we analyzed the balance between oxidized and reduced glutathione in lymphocytes of 10 patients with genetically confirmed LS and monitored the effects of glutathione status following 6 months of treatment with EPI-743, a novel redox therapeutic. METHODS: Lymphocytes were obtained from blood samples of 10 children with a genetically confirmed diagnosis of LS and in 20 healthy subjects. Total, reduced, oxidized and protein-bound glutathione levels were determined by HPLC analysis. Erythrocyte superoxide dismutase and glutathione peroxidase enzyme activities were measured by spectrophotometric assays. Plasma total thiols, carbonyl contents and malondialdehyde were assessed by spectrophotometric and fluorometric assays. RESULTS: A significant impairment of all glutathione forms was detected in patients, including a profound decrease of total and reduced glutathione (GSH) associated with high levels of all oxidized glutathione forms (GSSG+GS-Pro; OX). These findings negatively correlated with the glutathione peroxidase activity, which underwent a significant decrease in patients. After treatment with EPI-743, all patients showed a significant increase in reduced glutathione levels and 96% decrease of OX/GSH ratio. CONCLUSIONS: The data presented here strongly support glutathione as a "redox blood signature" in mitochondrial disorders and its use as a clinical trial endpoint in the development of mitochondrial disease therapies.

Non-myeloablative bone marrow transplant and platelet infusion can transiently improve the clinical outcome of mitochondrial neurogastrointestinal encephalopathy: a case report.

Mitochondrial neurogastrointestinal encephalopathy (MNGIE) is caused by deficiency in thymidine phosphorylase (TP), that regulates thymidine (dThd) and deoxyuridine (dUrd). Toxic levels of dThd and dUrd can lead to mitochondrial dysfunction by impairing mitochondrial DNA replication, causing GI and neurologic deterioration. We studied the impact of bone marrow transplant (BMT) and platelets, as a source of TP on the clinical outcome of MNGIE. We report a case of MNGIE, who presented with severe vomiting. Over time, he was non-ambulatory and his GI symptoms got progressively worse with severe dysphagia, abdominal pain episodes, persistent vomiting and diarrhea. Being unfit for intense conditioning regimen, he received a mini BMT, with mild conditioning regimen. Bone marrow was obtained from his HLA fully matched brother. One month after transplantation, donor chimerism in peripheral blood was 33%. Excellent clinical responses were achieved 3 months after transplantation and circulating donor cell chimerism decreased to 24% with a significant increase in platelet TP activity. Ten months post transplant the patient's symptoms recurred and fresh single donor platelets were infused, with a significant increase in platelet TP activity. Mini BMT and platelet transfusion can transiently increase circulating TP activity and might prevent progress of this fatal disease.

Assessment of thymidine phosphorylase function: measurement of plasma thymidine (and deoxyuridine) and thymidine phosphorylase activity.

We describe detailed methods to measure thymidine (dThd) and deoxyuridine (dUrd) concentrations and thymidine phosphorylase (TP) activity in biological samples. These protocols allow the detection of TP dysfunction in patients with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). Since the identification of mutations in TYMP, the gene encoding TP, as the cause of MNGIE (Nishino et al. Science 283:689-692, 1999), the assessment of TP dysfunction has become the best screening method to rule out or confirm MNGIE in patients. TYMP sequencing, to find the causative mutations, is only needed when TP dysfunction is detected. dThd and dUrd are measured by resolving these compounds with high-performance liquid chromatography (HPLC) followed by the spectrophotometric monitoring of the eluate absorbance at 267 nm (HPLC-UV). TP activity can be measured by an endpoint determination of the thymine formed after 1 h incubation of the buffy coat homogenate in the presence of a large excess of its substrate dThd, either spectrophotometrically or by HPLC-UV.

A novel mutation in the mitochondrial tRNA for tryptophan causing a late-onset mitochondrial encephalomyopathy.

BACKGROUND: Mitochondrial DNA (mtDNA) mutations are increasingly being recognized as causes of late-onset disease. We report a patient with a late-onset mitochondrial encephalomyopathy caused by a novel G > C transition in mtDNA at position 5556 in the gene encoding the tRNA for tryptophan (MTTW). AIMS: To investigate the cause of disease and assess the pathogenicity of this new mutation. METHODS: Clinical, histopathological and gene sequencing studies. Quantification of the mutation was performed in different tissues from the patient and two relatives and in single muscle fibres. RESULTS: The mutation was heteroplasmic, segregated in biochemically affected muscle fibres and was absent in blood. The level of mutation in skeletal muscle was higher than in brain, although the brain was clinically the most affected tissue. DISCUSSION: The 5556G > C mutation appears sporadic. It was not found in any of the family members tested, although some of them manifested disorders that can be associated with mtDNA disease. In addition to reporting the eighth mutation in MTTW, our case illustrates the challenges posed when assigning pathogenicity to mtDNA mutations.

Late-onset MNGIE without peripheral neuropathy due to incomplete loss of thymidine phosphorylase activity.

Mitochondrial NeuroGastroIntestinal Encephalomyopathy (MNGIE) is an autosomal recessive disorder characterized by severe gastrointestinal dysmotility, cachexia, peripheral neuropathy, ptosis, ophthalmoplegia, and leukoencephalopathy with early onset and severe prognosis. Mutations in the TYMP/ECGF1 gene cause a loss of thymidine phosphorylase catalytic activity, disrupting the homeostasis of intramitochondrial nucleotide pool. We report a woman with a very late onset of MNGIE, lacking peripheral neuropathy. Thymidine phosphorylase activity was markedly reduced in cultured fibroblasts, but only mildly reduced in buffy coat, where the defect is usually detected, and plasma thymidine was mildly increased compared to typical MNGIE patients. TYMP/ECGF1 analysis detected two heterozygous mutations, including a novel missense mutation. These findings indicate that a partial loss of thymidine phosphorylase activity may induce a late-onset and incomplete MNGIE phenotype.

Myoclonic epilepsy with ragged-red fibers without increased lactate levels.

Myoclonic epilepsy associated with ragged-red fibers is one of the mitochondrial encephalomyopathies. Pathogenic mitochondrial DNA mutations have been identified in the mitochondrial transfer RNA (tRNA)(Lys) at positions 8344 and 8356. Characteristics of myoclonic epilepsy associated with ragged-red fibers include myoclonic epilepsy, generalized epilepsy, hearing loss, exercise intolerance, lactic acidosis, and ragged-red fibers. The elevated lactate level is one of the most important symptoms needed to make a diagnosis of mitochondrial encephalomyopathy. In the present case, however, myoclonic epilepsy was associated with ragged-red fibers but without increased lactate levels. Therefore, myoclonic epilepsy associated with ragged-red fibers should be suspected in a patient who has myoclonic epilepsy that is difficult to control with antiepileptic medications and who has other symptoms of mitochondrial disease, such as mental retardation, even if the patient's lactate level is normal.

Treatment of mitochondrial neurogastrointestinal encephalomyopathy with dialysis.

OBJECTIVE: To study the effect of continuous ambulatory peritoneal dialysis on nucleoside levels and clinical course in a patient with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). Patient We studied a patient with genetically verified MNGIE, who prior to treatment had lost weight progressively, developed amenorrhea, vomited multiple times daily, and had abdominal pain. Intervention The patient was treated with peritoneal dialysis for 3 years, and the effect on symptoms and plasma concentrations of thymidine and deoxyuridine were monitored. RESULTS: Dialysis stopped vomiting and reduced abdominal pain, and the patient gained 5 kg in weight and started to menstruate again. Symptoms returned if dialysis was paused. Dialysis did not affect plasma nucleoside levels. CONCLUSIONS: This study shows an unambiguous clinical benefit of peritoneal dialysis on gastrointestinal symptoms in MNGIE. Dialysis did not affect nucleoside levels, indicating elevated thymidine and deoxyuridine levels are not solely responsible for the pathogenesis of MNGIE.

Determination of thymidine phosphorylase activity in human blood cells and fibroblasts by a nonradiochemical assay using reversed-phase high-performance liquid chromatography.

In this study, we demonstrated that the highest activity of thymidine phosphorylase (TP) was found in peripheral blood mononuclear (PBM) cells followed by that of thrombocytes and granulocytes whereas no activity of TP could be detected in erythrocytes. The activity of TP in leukocytes proved to be intermediate compared to the TP activity observed in PBM cells and granulocytes. The activity of TP also was readily detectable in human fibroblasts.

Allogeneic stem cell transplantation corrects biochemical derangements in 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.

Infusion of platelets transiently reduces nucleoside overload in MNGIE.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is caused by thymidine phosphorylase (TP) deficiency, which leads to toxic accumulations of thymidine (dThd) and deoxyuridine (dUrd). In this work, we report that infusion of platelets from healthy donors to patients with MNGIE restored transiently circulating TP and reduced plasma dThd and dUrd levels, suggesting that treatments to achieve permanent restoration of circulating TP such as allogeneic stem cell transplantation or gene transfer might be therapeutic.

Pre- and post-dialysis quantitative dosage of thymidine in urine and plasma of a MNGIE patient by using HPLC-ESI-MS/MS.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder characterized by severe gastrointestinal dysmotility, cachexia, ptosis, ophthalmoparesis, peripheral neuropathy and leukoencephalopathy. The disease is due to a thymidine phosphorylase defect. This enzyme catalyses the phosphorolysis of thymidine to thymine and deoxyribose 1-phosphate. For this reason, increased levels of thymidine in plasma and urine are found in MNGIE patients. Haemodialysis can reduce circulating plasma thymidine levels and can be beneficial in some MNGIE patients. We developed a fast analytical method based on HPLC-ESI-MS/MS capable of identifying pyrimidine nucleotides (thymine, cytosine, uracil) and nucleosides (thymidine, citidine, uridine) in plasma and urine after direct dilution of the samples without pre-treatment. In the patient studied, we observed a significant reduction of plasmatic and urinary thymidine levels during and after dialysis. However, we noted a progressive reduction of the initial thymidine level after some dialytic trials. This method will be useful not only for thymidine level follow-up during dialysis in MNGIE patients but also for the improvement of the diagnosis or diagnostic suspect in other pyrimidine defects such as dihydropyrimidine dehydrogenase deficiency, dihydropyrimidinase deficiency and ureidopropionase deficiency.

[Phenotype heterogeneity associated with mitochondrial DNA A3243G mutation].

OBJECTIVE: To discuss the clinical characteristics associated with mitochondrial DNA A3243G mutation. METHODS: Clinical manifestations as well as results of brain CT and/or MRI scanning, blood level of lactic acid and muscle biopsy results of 25 mitochondrial encephalomyopathies patients whose A3243G mutations were analyzed. RESULTS: Although all of the 25 patients carried mtDNA A3243G point mutation, their clinical manifestations varied greatly. Among them, there were 19 cases of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), 2 cases of encephalopathies which could not be classified into any specific type, 2 cases of floppy infants, one case of Kearns-Sayer syndrome (KSS) and one case of mitochondrial entero-myopathy. Most patients showed abnormal cranial radiological findings and ragged-red-fibers on muscle biopsies. Elevation of blood lactic acid was notably found in all of the 25 patients. CONCLUSIONS: Significant variations in clinical manifestation and brain images are the prominent features in patients with A3243G mutation. Mitochondrial diseases should be considered in patients with multiple organ involvement and elevated serum lactic acid mtDNA mutation examination is necessary for the diagnosis of mitochondrial diseases.

A novel thymidine phosphorylase mutation in a Spanish MNGIE patient.

A 29-year-old Spanish man presented with chronic intestinal pseudo-obstruction, progressive external ophthalmoplegia, peripheral neuropathy, and diffuse leukoencephalopathy. This combination of clinical features is characteristic of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). Genetic analysis revealed a novel 18-base pair (bp) duplication (5044-5061 dup) in exon 8 of the thymidine phosphorylase (TP) gene. The mutation is predicted to produce a 6 amino acid insertion in the alpha-beta-domain of the protein. This 18-bp insertion in the thymidine phosphorylase gene is the first duplication mutation identified in MNGIE.

Clinical laboratory monitoring of coenzyme Q10 use in neurologic and muscular diseases.

Coenzyme Q10 (Q10) is available as an over-the-counter dietary supplement in the United States. While its use could be considered a form of alternative therapy, the medical profession has embraced the use of Q10 in specific disease states, including a series of neurologic and muscular diseases. Clinical laboratory monitoring is available for measurement of total Q10 in plasma and tissue and for measurement of redox status, ie, the ratio of reduced and oxidized forms of Q10. Many published studies have been anecdotal, in part owing to the rarity of some diseases involved. Unfortunately, many studies do not report Q10 levels, and, thus, the relationship of clinical response to Q10 concentration in plasma frequently is not discernible. Consistent laboratory monitoring of patients treated with this compound would help ease interpretation of the results of the treatment, especially because so many formulations of Q10 exist in the marketplace, each with its own bioavailability characteristics. Q10 has an enviable safety profile and, thus, is ideal to study as an adjunct to more conventional therapy. Defining patient subpopulations and characteristics that predict benefit from exogenous Q10 and defining therapeutic ranges for those particular applications are major challenges in this field.

Ubiquinone and nicotinamide treatment of patients with the 3243A-->G mtDNA mutation.

The efficacy and safety of ubiquinone (Q10) and nicotinamide were evaluated in a 6-month open-label trial in patients with the 3243A-->G mitochondrial DNA mutation. Blood lactate and pyruvate concentrations decreased, but there was little clinical improvement. Q10 and nicotinamide were well tolerated, but two patients died suddenly and unexpectedly during the trial. These deaths may have been unrelated to treatment. The unpredictable course of the disease makes evaluation of the clinical response difficult.

Biochemical monitoring of the treatment in paediatric patients with mitochondrial disease.

Treatment strategies in mitochondrial diseases consist of several drugs that diminish the deleterious effects of the abnormal respiratory chain function, reduce the presence of toxic agents or correct deficiencies in essential cofactors. In this study we evaluated the monitoring of tocopherol, carnitine and ubiquinone concentrations in a group of paediatric patients during a follow-up period of 18 months and the response to treatment of these patients by means of the determination of blood lactate, plasma alanine and oxygen consumption by lymphocytes in relation to the clinical status of the patients. Tocopherol, carnitine and ubiquinone concentrations were easily corrected with therapy. Blood lactate proved the best biochemical tool to assess the response to treatment in paediatric patients. According to our results, improvement or stabilization of the clinical course seems to be more related to the biochemical or molecular defect than to the effectiveness of the treatment.