Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0031117 (peripheral neuropathy)
 10,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder defined clinically by severe gastrointestinal dysmotility; cachexia; ptosis, ophthalmoparesis, or both; peripheral neuropathy; leukoencephalopathy; and mitochondrial abnormalities. The disease is caused by mutations in the thymidine phosphorylase (TP) gene. TP protein catalyzes phosphorolysis of thymidine to thymine and deoxyribose 1-phosphate. We identified 21 probands (35 patients) who fulfilled our clinical criteria for MNGIE. MNGIE has clinically homogeneous features but varies in age at onset and rate of progression. Gastrointestinal dysmotility is the most prominent manifestation, with recurrent diarrhea, borborygmi, and intestinal pseudo-obstruction. Patients usually die in early adulthood (mean, 37.6 years; range, 26-58 years). Cerebral leukodystrophy is characteristic. Mitochondrial DNA (mtDNA) has depletion, multiple deletions, or both. We have identified 16 TP mutations. Homozygous or compound heterozygous mutations were present in all patients tested. Leukocyte TP activity was reduced drastically in all patients tested, 0.009 +/- 0.021 micromol/hr/mg (mean +/- SD; n = 16), compared with controls, 0.67 +/- 0.21 micromol/hr/mg (n = 19). MNGIE is a recognizable clinical syndrome caused by mutations in thymidine phosphorylase. Severe reduction of TP activity in leukocytes is diagnostic. Altered mitochondrial nucleoside and nucleotide pools may impair mtDNA replication, repair, or both.
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PMID:Mitochondrial neurogastrointestinal encephalomyopathy: an autosomal recessive disorder due to thymidine phosphorylase mutations. 1085 45

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a unique autosomal recessive disorder with mitochondrial DNA alterations. The disease is characterized clinically by ptosis, progressive external ophthalmoparesis, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and leukoencephalopathy. Muscle biopsies typically reveal mitochondrial abnormalities including ragged-red fibers and focal cytochrome c oxidase deficiency. Analysis of mitochondrial DNA in skeletal muscle shows partial depletion, multiple deletions, or both. To identify the cause of MNGIE, we mapped the disease locus to chromosome 22q13.32-qter. Within this region, we identified the gene encoding thymidine phosphorylase as the MNGIE gene. We have identified homozygous or compound-heterozygous thymidine phosphorylase gene mutations in 35 MNGIE patients (21 families) from diverse ethnic groups, including: Ashkenazi Jewish, Western European, Jamaican, Hispanic, and Japanese. We confirmed pathogenicity of the mutations by a spectrophotometric assay of thymidine phosphorylase activity with peripheral leukocytes of 15 MNGIE patients. Thymidine phosphorylase enzymatic activity was severely reduced, thus enabling us to conclude that the loss-of-function mutations in thymidine phosphorylase gene cause MNGIE. Thymidine phosphorylase catabolizes thymidine to thymine. In agreement with this notion, we noted that plasma thymidine level is increased more than 20-fold in MNGIE patients compared to controls. Therefore, we have hypothesized that increased thymidine causes mitochondrial nucleotide pool imbalance which, in turn, leads to motochondrial DNA alterations, via a mitochondria-specific thymidine salvage pathway. The identification of the MNGIE gene has allowed us to classify MNGIE as a disease of nucleoside dysmetabolism. We may be entering a new era of research on mitochondrial nucleoside metabolism.
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PMID:MNGIE: from nuclear DNA to mitochondrial DNA. 1116 60

The antiviral drug 2',3'-didehydro-3'-deoxythymidine (D4T; also know as stavudine and Zerit), which is used against human immunodeficiency virus (HIV), causes delayed toxicity (peripheral neuropathy) in long-term use. After examining a series of 2',3'-didehydro-3'-deoxy-4'-substituted thymidine (4'-substituted D4T) analogs, 4'-ethynyl D4T was found to have a fivefold-better antiviral effect and to cause less cellular and mitochondrial toxicity than D4T. The antiviral activity of this compound can be reversed by dThd but not by dCyd. The compound acted synergistically with beta-L-2',3'-deoxy-3'-thiacytidine (also known as lamivudine) and beta-L-2',3'-dideoxy-2',3'-didehydro-5-fluorocytidine (also known as elvucitabine) and additively with 2',3'-dideoxyinosine (also known as didanosine and Videx) and 3'-azido-3'-deoxythymidine (also known as Retovir and zidovudine) against HIV. 4'-Ethynyl D4T is phosphorylated by purified human thymidine kinase 1 (TK-1) from CEM cells with a faster relative V(max) and a lower K(m) value than D4T. The efficiency of TK-1 in the phosphorylation of 4'-ethynyl D4T is fourfold better than that of D4T. While D4T is broken down by the catabolic enzyme thymidine phosphorylase, the level of breakdown of 4'-ethynyl D4T was below detection. Since 4'-ethynyl D4T has increased anti-HIV activity and decreased toxicity and interacts favorably with other currently used anti-HIV drugs, it should be considered for further development as an anti-HIV drug.
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PMID:Novel 4'-substituted stavudine analog with improved anti-human immunodeficiency virus activity and decreased cytotoxicity. 1510 15

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in the gene encoding thymidine phosphorylase (TP). The disease is characterized clinically by impaired eye movements, gastrointestinal dysmotility, cachexia, peripheral neuropathy, myopathy, and leukoencephalopathy. Molecular genetic studies of MNGIE patients' tissues have revealed multiple deletions, depletion, and site-specific point mutations of mitochondrial DNA. TP is a cytosolic enzyme required for nucleoside homeostasis. In MNGIE, TP activity is severely reduced and consequently levels of thymidine and deoxyuridine in plasma are dramatically elevated. We have hypothesized that the increased levels of intracellular thymidine and deoxyuridine cause imbalances of mitochondrial nucleotide pools that, in turn, lead to the mtDNA abnormalities. MNGIE was the first molecularly characterized genetic disorder caused by abnormal mitochondrial nucleoside/nucleotide metabolism. Future studies are likely to reveal further insight into this expanding group of diseases.
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PMID:Thymidine phosphorylase deficiency causes MNGIE: an autosomal recessive mitochondrial disorder. 1557 Dec 33

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.
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PMID:A novel thymidine phosphorylase mutation in a Spanish MNGIE patient. 1560 8

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder characterized by ptosis and progressive external ophthalmoplegia, peripheral neuropathy, severe gastrointestinal dysmotility, cachexia and leukoencephalopathy. Muscle biopsies of MNGIE patients have revealed morphologically abnormal mitochondria and defects of respiratory chain enzymes. In addition, patients harbor depletion, multiple deletions, and point mutations of mitochondrial DNA (mtDNA). This disorder is caused by loss-of-function mutations in the gene encoding thymidine phosphorylase (TP) a cytosolic enzyme. In MNGIE patients, TP activity is very low or absent resulting in dramatically elevated levels of plasma thymidine and deoxyuridine. We have hypothesized that the increased levels of thymidine and deoxyuridine cause mitochondrial nucleotide pool imbalances that, in turn, generate mtDNA alterations.
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PMID:Thymidine phosphorylase mutations cause instability of mitochondrial DNA. 1597 38

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease with mitochondrial DNA (mtDNA) alterations and is caused by mutations in the nuclear gene encoding thymidine phosphorylase (TP). The cardinal clinical manifestations are ptosis, ophthalmoparesis, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and leukoencephalopathy. Skeletal muscle shows mitochondrial abnormalities, including ragged-red fibers and cytochrome c oxidase deficiency, together with mtDNA depletion, multiple deletions or both. In MNGIE patients, TP mutations cause a loss-of-function of the cytosolic enzyme, TP. As a direct consequence of the TP defect, thymidine metabolism is altered. High blood levels of this nucleoside are likely to lead to mtDNA defects even in cells that do not express TP, such as skeletal muscle. We hypothesize that high concentrations of thymidine affect dNTP (deoxyribonucleoside triphosphate) metabolism in mitochondria more than in cytosol or nuclei, because mitochondrial dNTPs depend mainly on the thymidine salvage pathway, whereas nuclear dNTPs depend mostly on de novo pathway. The imbalance in the mitochondrial dNTP homeostasis affects mtDNA replication, leading to mitochondrial dysfunction.
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PMID:Mitochondrial neurogastrointestinal encephalomyopathy and thymidine metabolism: results and hypotheses. 1612 Mar 16

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.
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PMID:Pre- and post-dialysis quantitative dosage of thymidine in urine and plasma of a MNGIE patient by using HPLC-ESI-MS/MS. 1649 12

Patients diagnosed with abdominal pain related to mitochondrial neurogastrointestinal encephalopathy (MNGIE) may benefit from splanchnic nerve blockade. MNGIE, varying in age of onset and rate of progression, is caused by loss of function mutation in thymidine phosphorylase gene. Gastrointestinal dysmotility, pseudo-obstruction and demyelinating sensorimotor peripheral neuropathy (stocking-glove sensory loss, absent tendon reflexes, distal limb weakness, and wasting) are the most prominent manifestations. Patients usually die in early adulthood (mean 37.6 years; range 26-58 years). We report a case of an 18-year-old patient with MNGIE. Our patient's abdominal pain was relieved after splanchnic nerve blockade.
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PMID:Abdominal pain related to mitochondrial neurogastrointestinal encephalomyopathy syndrome may benefit from splanchnic nerve blockade. 1697 39

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive, multisystem disorder, which is clinically defined by ptosis, ophthalmoparesis, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and leukoencephalopathy. MNGIE is caused by mutations in the nuclear gene, endothelial cell growth factor 1 (ECGF1), encoding thymidine phosphorylase (TP). ECGF1 mutations cause severe loss of TP activity, abnormal accumulations of thymidine and deoxyuridine in plasma, and alterations of mitochondrial DNA. Here, we report the first Thai patient with MNGIE confirmed genetically by the identification of a homozygous novel ECGF1 gene mutation, c.100insC, which causes a frameshift and premature truncation of TP protein.
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PMID:A novel ECGF1 mutation in a Thai patient with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). 1754 74


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