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Angela T S Wyse - One of the best experts on this subject based on the ideXlab platform.
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Hypermethioninemia induces memory deficits and morphological changes in hippocampus of young rats implications on pathogenesis
Amino Acids, 2020Co-Authors: Mayara Sandrielly Pereira Soares, Daniella De S Moreira, Angela T S Wyse, Luiza Spohr, Anita Ávila Souza, Bruna Da Silveira De Mattos, Rejane Giacomelli Tavares, Cassiana Siebert, Fabiano B Carvalho, Francine Luciano RahmeierAbstract:The aim of this study was to investigate the effect of the chronic administration of methionine (Met) and/or its metabolite, methionine sulfoxide (MetO), on the behavior and neurochemical parameters of young rats. Rats were treated with saline (control), Met (0.2–0.4 g/kg), MetO (0.05–0.1 g/kg), and/or a combination of Met + MetO, subcutaneously twice a day from postnatal day 6 (P6) to P28. The results showed that Met, MetO, and Met + MetO impaired short-term and spatial memories (P 0.05). Acetylcholinesterase activity was increased in the cerebral cortex, hippocampus, and striatum following Met and/or MetO (P < 0.05) treatment, while Na+, K+-ATPase activity was reduced in the hippocampus (P < 0.05). There was an increase in the level of thiobarbituric acid reactive substances (TBARS) in the cerebral cortex in Met-, MetO-, and Met + MetO-treated rats (P < 0.05). Met and/or MetO treatment reduced superoxide dismutase, catalase, and glutathione peroxidase activity, total thiol content, and nitrite levels, and increased reactive oxygen species and TBARS levels in the hippocampus and striatum (P < 0.05). Hippocampal brain-derived neurotrophic factor was reduced by MetO and Met + MetO compared with the control group. The number of NeuN-positive cells was decreased in the CA3 in Met + MetO group and in the dentate gyrus in the Met, MetO, and Met + MetO groups compared to control group (P < 0.05). Taken together, these findings further increase our understanding of changes in the brain in Hypermethioninemia by elucidating behavioral alterations, biological mechanisms, and the vulnerability of brain function to high concentrations of Met and MetO.
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the neuroprotective role of melatonin in a gestational Hypermethioninemia model
International Journal of Developmental Neuroscience, 2019Co-Authors: Paula W Figueiro, Daniella De S Moreira, Tiago Dos Santos, Caroline A Prezzi, Francieli Rohden, Maria Cristina Faccioniheuser, Vanusa Manfredini, Carlos Alexandre Netto, Angela T S WyseAbstract:Abstract Elevated levels of methionine in blood characterize the Hypermethioninemia, which may have genetic or non-genetic origin, as for example from high protein diet. Born rats from hypermethioninemic mothers presented cerebral oxidative stress, inhibition of Na+,K+-ATPase, memory deficit and ultrastructure cerebral changes. Melatonin is a hormone involved in circadian rhythm and has antioxidant effects. The aim of this study was to verify the possible neuroprotective effects of melatonin administration in hypermethioninemic pregnant rats on damage to biomolecules (Na+,K+-ATPase, sulfhydryl content and DNA damage index) and behavior (open field, novel object recognition and water maze tasks), as well as its effect on cells morphology by electron microscopy in offspring. Wistar female rats received methionine (2.68 μmol/g body weight) and/or melatonin (10 mg/kg body weight) by subcutaneous injections during entire pregnancy. Control rats received saline. Biochemical analyzes were performed at 21 and 30 days of life of offspring and behavioral analyzes were performed only at 30 days of age in male pups. Results showed that gestational Hypermethioninemia diminished Na+,K+-ATPase activity and sulfhydryl content and increased DNA damage at 21 and 30 days of life. Melatonin was able to totally prevent Na+,K+-ATPase activity alteration at 21 days and partially prevent its alteration at 30 days of rats life. Melatonin was unable in to prevent sulfhydryl and DNA damage at two ages. It also improved DNA damage, but not at level of saline animals (controls). Regarding to behavioral tests, data showed that pups exposed to gestational Hypermethioninemia decreased reference memory in water maze, spent more time to the center of the open field and did not differentiate the objects in the recognition test. Melatonin was able to prevent the deficit in novel object recognition task. Electron microscopy revealed ultrastructure alterations in neurons of hypermethioninemic at both ages of offspring, whose were prevented by melatonin. These findings suggest that melatonin may be a good neuroprotective to minimize the harmful effects of gestational Hypermethioninemia on offspring.
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Mechanistic basis of Hypermethioninemia
Amino Acids, 2016Co-Authors: Bruna M Schweinberger, Angela T S WyseAbstract:Hypermethioninemia is a condition defined as elevated plasma methionine levels and may be a consequence of different conditions that include non-genetic and genetic causes. In severe cases, Hypermethioninemia may lead to development of neurological and hepatic impairments, but mechanisms are still not well elucidated. Therefore, this review aims to reunite the knowledge acquired about the methionine-induced brain and liver toxicity focusing on the results obtained by studies from patients, in vitro experiments, and in vivo animal models. In general, some studies have shown that methionine decreases Na^+,K^+-ATPase activity, induces oxidative stress, increases acetylcholinesterase activity, and leads to dendritic spine downregulation in brain. Concerning to liver, Hypermethioninemia seems to provoke changes in cell morphology, lipid accumulation, oxidative stress, inflammation, and ATP depletion. It is possible to infer that oxidative damage is one of the most important mechanisms responsible for methionine toxicity, since different studies showed that this amino acid induces oxidative stress in brain and liver tissues. Besides, reactive oxygen species may mediate other alterations induced by methionine, such as the reduction in brain Na^+,K^+-ATPase activity, and liver inflammation.
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development of an animal model for gestational Hypermethioninemia in rat and its effect on brain na k atpase mg 2 atpase activity and oxidative status of the offspring
Metabolic Brain Disease, 2014Co-Authors: Bruna M Schweinberger, Emilene B S Scherer, Ligia Schwieder, Angela Sitta, C R Vargas, Angela T S WyseAbstract:In the present study we developed a chemically induced experimental model for gestational Hypermethioninemia in rats and evaluated in the offspring the activities of Na+,K+-ATPase and Mg2+-ATPase, as well as oxidative stress parameters, namely sulfhydryl content, thiobarbituric acid-reactive substances and the antioxidant enzymes superoxide dismutase and catalase in encephalon. Serum and encephalon levels of methionine and total homocysteine were also evaluated in mother rats and in the offspring. Pregnant Wistar rats received two daily subcutaneous injections of methionine throughout the gestational period (21 days). During the treatment, a group of pregnant rats received dose 1 (1.34 μmol methionine/g body weight) and the other one received dose 2 (2.68 μmol methionine/g body weight). Control group received saline. After the rats give birth, a first group of pups was killed at the 7th day of life and the second group at the 21th day of life for removal of serum and encephalon. Mother rats were killed at the 21th day postpartum for removal of serum and encephalon. Both doses 1 and 2 increased methionine levels in encephalon of the mother rats and dose 2 increased methionine levels in encephalon of the offspring. Maternal Hypermethioninemia also decreased the activities of Na+,K+-ATPase, Mg2+-ATPase and catalase, as well as reduced total sulfhydryl content in the encephalon of the pups. This chemical model seems to be appropriate for studies aiming to investigate the effect of maternal Hypermethioninemia on the developing brain during gestation in order to clarify possible neurochemical changes in the offspring.
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acute and chronic Hypermethioninemia alter na k atpase activity in rat hippocampus prevention by antioxidants
International Journal of Developmental Neuroscience, 2011Co-Authors: Francieli M Stefanello, Andrea G K Ferreira, Talita Carneiro Brandao Pereira, Maira J Da Cunha, Carla Denise Bonan, Mauricio Reis Bogo, Angela T S WyseAbstract:Abstract In the current study we initially investigated the influence of antioxidants (vitamins E plus C) on the effect mediated by acute and chronic administration of methionine (Met) on Na + ,K + -ATPase activity in rat hippocampus. We also verified whether the alterations on the enzyme after administration of Met and/or antioxidants were associated with changes in relative expression of Na + ,K + -ATPase catalytic subunits (isoforms α1, α2 and α3). For acute treatment, young rats received a single subcutaneous injection of Met or saline (control) and were sacrificed 12 h later. In another set of experiments, rats were pretreated for 1 week with daily intraperitoneal administration of vitamins E (40 mg/kg) and C (100 mg/kg) or saline. After that, rats received a single injection of Met or saline and were killed 12 h later. For chronic treatment, Met was administered to rats from the 6th to the 28th day of life; controls and treated rats were sacrificed 12 h after the last injection. In parallel to chronic treatment, rats received a daily intraperitoneal injection of vitamins E and C from the 6th to the 28th day of life and were killed 12 h after the last injection. Results showed that administration of antioxidants partially prevented the inhibition of enzyme activity caused by acute and chronic Hypermethioninemia. Besides, we demonstrated that transcription of catalytic subunits of Na + ,K + -ATPase was not altered by chronic and acute exposure to Met and/or vitamins E plus C. These data strongly suggest the oxidative damage as one possible mechanism involved in the reduction of Na + ,K + -ATPase activity caused by Hypermethioninemia and if confirmed in human beings, we might propose the use of antioxidants as an adjuvant therapy in hypermethioninemic patients.
George F Grady - One of the best experts on this subject based on the ideXlab platform.
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tandem mass spectrometric analysis for amino organic and fatty acid disorders in newborn dried blood spots a two year summary from the new england newborn screening program
Clinical Chemistry, 2001Co-Authors: Thomas H Zytkovicz, Eileen F Fitzgerald, Deborah Marsden, Cecilia Larson, Vivian E Shih, Donna M Johnson, Arnold W Strauss, Anne Marie Comeau, Roger B Eaton, George F GradyAbstract:BACKGROUND: Tandem mass spectrometry (MS/MS) is rapidly being adopted by newborn screening programs to screen dried blood spots for >20 markers of disease in a single assay. Limited information is available for setting the marker cutoffs and for the resulting positive predictive values. METHODS: We screened >160 000 newborns by MS/MS. The markers were extracted from blood spots into a methanol solution with deuterium-labeled internal standards and then were derivatized before analysis by MS/MS. Multiple reaction monitoring of each sample for the markers of interest was accomplished in approximately 1.9 min. Cutoffs for each marker were set at 6-13 SD above the population mean. RESULTS: We identified 22 babies with amino acid disorders (7 phenylketonuria, 11 hyperphenylalaninemia, 1 maple syrup urine disease, 1 Hypermethioninemia, 1 arginosuccinate lyase deficiency, and 1 argininemia) and 20 infants with fatty and organic acid disorders (10 medium-chain acyl-CoA dehydrogenase deficiencies, 5 presumptive short-chain acyl-CoA dehydrogenase deficiencies, 2 propionic acidemias, 1 carnitine palmitoyltransferase II deficiency, 1 methylcrotonyl-CoA carboxylase deficiency, and 1 presumptive very-long chain acyl-CoA dehydrogenase deficiency). Approximately 0.3% of all newborns screened were flagged for either amino acid or acylcarnitine markers; approximately one-half of all the flagged infants were from the 5% of newborns who required neonatal intensive care or had birth weights <1500 g. CONCLUSIONS: In screening for 23 metabolic disorders by MS/MS, an mean positive predictive value of 8% can be achieved when using cutoffs for individual markers determined empirically on newborns.
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tandem mass spectrometric analysis for amino organic and fatty acid disorders in newborn dried blood spots a two year summary from the new england newborn screening program
Clinical Chemistry, 2001Co-Authors: Thomas H Zytkovicz, Eileen F Fitzgerald, Vivian E Shih, Arnold W Strauss, Anne Marie Comeau, Deborah Marsde, Cecilia Larso, Donna M Johnso, Roge Eato, George F GradyAbstract:Background: Tandem mass spectrometry (MS/MS) is rapidly being adopted by newborn screening programs to screen dried blood spots for >20 markers of disease in a single assay. Limited information is available for setting the marker cutoffs and for the resulting positive predictive values. Methods: We screened >160 000 newborns by MS/MS. The markers were extracted from blood spots into a methanol solution with deuterium-labeled internal standards and then were derivatized before analysis by MS/MS. Multiple reaction monitoring of each sample for the markers of interest was accomplished in ∼1.9 min. Cutoffs for each marker were set at 6–13 SD above the population mean. Results: We identified 22 babies with amino acid disorders (7 phenylketonuria, 11 hyperphenylalaninemia, 1 maple syrup urine disease, 1 Hypermethioninemia, 1 arginosuccinate lyase deficiency, and 1 argininemia) and 20 infants with fatty and organic acid disorders (10 medium-chain acyl-CoA dehydrogenase deficiencies, 5 presumptive short-chain acyl-CoA dehydrogenase deficiencies, 2 propionic acidemias, 1 carnitine palmitoyltransferase II deficiency, 1 methylcrotonyl-CoA carboxylase deficiency, and 1 presumptive very-long chain acyl-CoA dehydrogenase deficiency). Approximately 0.3% of all newborns screened were flagged for either amino acid or acylcarnitine markers; approximately one-half of all the flagged infants were from the 5% of newborns who required neonatal intensive care or had birth weights <1500 g. Conclusions: In screening for 23 metabolic disorders by MS/MS, an mean positive predictive value of 8% can be achieved when using cutoffs for individual markers determined empirically on newborns.
Janice Yang Chou - One of the best experts on this subject based on the ideXlab platform.
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methionine adenosyltransferase i iii deficiency novel mutations and clinical variations
American Journal of Human Genetics, 2000Co-Authors: Margaret E Chamberlin, Tsuneyuki Ubagai, Harvey L Levy, Harvey S Mudd, Janet A Thomas, Vivian Y Pao, Thien Nguyen, Carol L Greene, Cynthia Freehauf, Janice Yang ChouAbstract:Summary Methionine adenosyltransferase (MAT) I/III deficiency, caused by mutations in the MAT1A gene, is characterized by persistent Hypermethioninemia without elevated homocysteine or tyrosine. Clinical manifestations are variable and poorly understood, although a number of individuals with homozygous null mutations in MAT1A have neurological problems, including brain demyelination. We analyzed MAT1A in seven hypermethioninemic individuals, to provide insight into the relationship between genotype and phenotype. We identified six novel mutations and demonstrated that mutations resulting in high plasma methionines may signal clinical difficulties. Two patients—a compound heterozygote for truncating and severely inactivating missense mutations and a homozygote for an aberrant splicing MAT1A mutation—have plasma methionine in the 1,226–1,870 μM range (normal 5–35 μM) and manifest abnormalities of the brain gray matter or signs of brain demyelination. Another compound heterozygote for truncating and inactivating missense mutations has 770–1,240 μM plasma methionine and mild cognitive impairment. Four individuals carrying either two inactivating missense mutations or the single-allelic R264H mutation have 105–467 μM plasma methionine and are clinically unaffected. Our data underscore the necessity of further studies to firmly establish the relationship between genotypes in MAT I/III deficiency and clinical phenotypes, to elucidate the molecular bases of variability in manifestations of MAT1A mutations.
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molecular genetics of hepatic methionine adenosyltransferase deficiency
Pharmacology & Therapeutics, 2000Co-Authors: Janice Yang ChouAbstract:Abstract Hepatic methionine adenosyltransferase (MAT) deficiency is caused by mutations in the human MAT1A gene that abolish or reduce hepatic MAT activity that catalyzes the synthesis of S -adenosylmethionine from methionine and ATP. This genetic disorder is characterized by isolated persistent Hypermethioninemia in the absence of cystathionine β-synthase deficiency, tyrosinemia, or liver disease. Depending on the nature of the genetic defect, hepatic MAT deficiency can be transmitted either as an autosomal recessive or dominant trait. Genetic analyses have revealed that mutations identified in the MAT1A gene only partially inactivate enzymatic activity, which is consistent with the fact that most hepatic MAT-deficient individuals are clinically well. Two hypermethioninemic individuals with null MAT1A mutations have developed neurological problems, including brain demyelination, although this correlation is by no means absolute. Presently, it is recommended that a DNA-based diagnosis should be performed for isolated hypermethioninemic individuals with unusually high plasma methionine levels to assess if therapy aimed at the prevention of neurological manifestations is warranted. Published 1999 by Elsevier Science Inc. All rights reserved.
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dominant inheritance of isolated Hypermethioninemia is associated with a mutation in the human methionine adenosyltransferase 1a gene
American Journal of Human Genetics, 1997Co-Authors: Margaret E Chamberlin, S H Mudd, Tsuneyuki Ubagai, Harvey L Levy, Janice Yang ChouAbstract:Methionine adenosyltransferase (MAT) I/III deficiency, characterized by isolated persistent Hypermethioninemia, is caused by mutations in the MAT1A gene encoding MAT(alpha)1, the subunit of major hepatic enzymes MAT I ([alpha1]4) and III([alpha1]2). We have characterized 10 MAT1A mutations in MAT I/III-deficient individuals and shown that the associated hypermethioninemic phenotype was inherited as an autosomal recessive trait. However, dominant inheritance of Hypermethioninemia, also hypothesized to be caused by MAT I/III deficiency, has been reported in two families. Here we show that the only mutation uncovered in one of these families, G, is a G-->A transition at nt 791 in exon VII of one MAT1A allele that converts an arginine at position 264 to a histidine (R264H). This single allelic R264H mutation was subsequently identified in two hypermethioninemic individuals in an additional family, C. Family C members were also found to inherit Hypermethioninemia in a dominant fashion, and the available affected members analyzed carried the single allelic R264H mutation. Substitution of R-264 with histidine (R264H, the naturally occurring mutant), leucine (R264L), aspartic acid (R264D), or glutamic acid (R264E) greatly reduced MAT activity and severely impaired the ability of the MAT(alpha)1 subunits to form homodimers essential for optimal catalytic activity. On the other hand, when lysine was substituted for R-264 (R264K), the mutant alpha1 subunit was able to form dimers that retain significant MAT activity, suggesting that amino acid 264 is involved in intersubunit salt-bridge formation. Cotransfection studies show that R264/R264H MAT(alpha)1 heterodimers are enzymatically inactive, thus providing an explanation for the R264H-mediated dominant inheritance of Hypermethioninemia.
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demyelination of the brain is associated with methionine adenosyltransferase i iii deficiency
Journal of Clinical Investigation, 1996Co-Authors: Margaret E Chamberlin, Tsuneyuki Ubagai, S H Mudd, W G Wilson, J V Leonard, Janice Yang ChouAbstract:Individuals deficient in hepatic methionine adenosyltransferase (MAT) activity (MAT I/III deficiency) have been demonstrated to contain mutations in the gene (MATA1) that encodes the major hepatic forms, MAT I and III. MAT I/III deficiency is characterized by isolated persistent Hypermethioninemia and, in some cases, unusual breath odor. Most individuals with isolated Hypermethioninemia have been free of major clinical difficulties. Therefore a definitive diagnosis of MAT I/III deficiency, which requires hepatic biopsy, is not routinely made. However, two individuals with isolated Hypermethioninemia have developed abnormal neurological problems, including brain demyelination, suggesting that MAT I/III deficiency can be deleterious. In the present study we have examined the MATA1 gene of eight hypermethioninemic individuals, including the two with demyelination of the brain. Mutations that abolish or reduce the MAT activity were detected in the MATA1 gene of all eight individuals. Both patients with demyelination are homozygous for mutations that alter the reading frame of the encoded protein such that the predicted MATalpha1 subunits are truncated and enzymatically inactive. The product of MAT, S-adenosylmethionine (AdoMet), is the major methyl donor for a large number of biologically important compounds including the two major myelin phospholipids, phosphatidylcholine and sphingomyelin. Both are synthesized primarily in the liver. Our findings demonstrate that isolated persistent Hypermethioninemia is a marker of MAT I/III deficiency, and that complete lack of MAT I/III activity can lead to neurological abnormalities. Therefore, a DNA-based diagnosis should be performed for individuals with isolated Hypermethioninemia to assess if therapy aimed at the prevention of neurological manifestations is warranted.
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molecular mechanisms of an inborn error of methionine pathway methionine adenosyltransferase deficiency
Journal of Clinical Investigation, 1995Co-Authors: Tsuneyuki Ubagai, Kejian Lei, S Huang, S H Mudd, Harvey L Levy, Janice Yang ChouAbstract:Methionine adenosyltransferase (MAT) is a key enzyme in transmethylation, transsulfuration, and the biosynthesis of polyamines. Genetic deficiency of alpha/beta-MAT causes isolated persistent Hypermethioninemia and, in some cases, unusual breath odor or neural demyelination. However, the molecular mechanism(s) underlying this deficiency has not been clearly defined. In this study, we characterized the human alpha/beta-MAT transcription unit and identified several mutations in the gene of patients with enzymatically confirmed diagnosis of MAT deficiency. Site-directed mutagenesis and transient expression assays demonstrated that these mutations partially inactivate MAT activity. These results establish the molecular basis of this disorder and allow for the development of DNA-based methodologies to investigate and diagnose hypermethioninemic individuals suspected of having abnormalities at this locus.
S H Mudd - One of the best experts on this subject based on the ideXlab platform.
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hypermethioninaemia due to methionine adenosyltransferase i iii mat i iii deficiency diagnosis in an expanded neonatal screening programme
Journal of Inherited Metabolic Disease, 2008Co-Authors: Maria L Couce, Fernando J Corrales, M D Boveda, Daisy E Castineiras, M I Mora, Jose M Fraga, S H MuddAbstract:The Expanded Newborn Screening Program (MS/MS) in the region of Galicia (NW Spain) was initiated in 2000 and includes the measurement of methionine levels in dried blood spots. Between June 2000 and June 2007, 140 818 newborns were analysed, and six cases of persistent hypermethioninaemia were detected: one homocystinuria due to cystathionine β-synthase (CβS) deficiency, and five methionine adenosyltransferase I/III (MAT I/III) deficiencies. The five cases of MAT I/III deficiency represent an incidence of 1/28 163 newborns. In these five patients, methionine levels in dried blood spots ranged from 50 to 147 μmol/L. At confirmation of the persistence of the hypermethioninaemia in a subsequent plasma sample, plasma methionine concentrations were moderately elevated in 4 of the 5 patients (mean 256 μmol/L), while total homocysteine (tHcy) was normal; the remaining patient showed plasma methionine of 573 μmol/L and tHcy of 22.8 μmol/L. All five patients were heterozygous for the same dominant mutation, R264H in the MAT1A gene. With a diet not exceeding recommended protein requirements for their age, all patients maintained methionine levels below 300 μmol/L. Currently, with a mean of 2.5 years since diagnosis, the patients are asymptomatic and show developmental quotients within the normal range. Our results show a rather high frequency of hypermethioninaemia due to MAT I/III deficiency in the Galician neonatal population, indicating a need for further studies to evaluate the impact of persistent isolated hypermethioninaemia in neonatal screening programmes.
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methionine adenosyltransferase i iii deficiency two korean compound heterozygous siblings with a novel mutation
Journal of Inherited Metabolic Disease, 2003Co-Authors: Sook Kim, Fernando J Corrales, Jose M Mato, Harvey L Levy, Enrique Santamaria, T E Jeong, S H MuddAbstract:Two Korean sisters, one detected during neonatal screening, the other ascertained at age 3 years during family screening, have persistent hypermethioninaemia without elevation of plasma tyrosine or severe liver disease. Plasma total homocysteine (tHcy) is mildly elevated, but not so markedly as to establish a diagnosis of homocystinuria due to cystathionine beta-synthase (CBS) deficiency. CBS deficiency was ruled out by the presence of slightly elevated concentrations of plasma cystathionine. Although the plasma concentrations of methionine were markedly elevated, plasma S-adenosylmethionine (AdoMet) was not. This pattern of metabolic abnormalities suggested that the patients have deficient activity of methionine adenosyltransferase (MAT) in their livers (MAT I/III deficiency). Molecular genetic studies demonstrate that each patient is a compound heterozygote for two mutations in MAT1A, the gene that encodes the catalytic subunit that composes MAT I and MAT III: a previously known inactivating G378S point mutation, and a novel W387X truncating mutation. W387X mutant protein, expressed in E. coli and purified, has about 75% of wild-type activity. Negative subunit interaction between the mutant subunits is suggested to explain the hypermethioninaemia of these sisters. They have had normal growth and development and have no mental retardation, neurological abnormalities, or other clinical problems. They are the first individuals of Korean descent proven to have MAT I/III deficiency.
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dominant inheritance of isolated Hypermethioninemia is associated with a mutation in the human methionine adenosyltransferase 1a gene
American Journal of Human Genetics, 1997Co-Authors: Margaret E Chamberlin, S H Mudd, Tsuneyuki Ubagai, Harvey L Levy, Janice Yang ChouAbstract:Methionine adenosyltransferase (MAT) I/III deficiency, characterized by isolated persistent Hypermethioninemia, is caused by mutations in the MAT1A gene encoding MAT(alpha)1, the subunit of major hepatic enzymes MAT I ([alpha1]4) and III([alpha1]2). We have characterized 10 MAT1A mutations in MAT I/III-deficient individuals and shown that the associated hypermethioninemic phenotype was inherited as an autosomal recessive trait. However, dominant inheritance of Hypermethioninemia, also hypothesized to be caused by MAT I/III deficiency, has been reported in two families. Here we show that the only mutation uncovered in one of these families, G, is a G-->A transition at nt 791 in exon VII of one MAT1A allele that converts an arginine at position 264 to a histidine (R264H). This single allelic R264H mutation was subsequently identified in two hypermethioninemic individuals in an additional family, C. Family C members were also found to inherit Hypermethioninemia in a dominant fashion, and the available affected members analyzed carried the single allelic R264H mutation. Substitution of R-264 with histidine (R264H, the naturally occurring mutant), leucine (R264L), aspartic acid (R264D), or glutamic acid (R264E) greatly reduced MAT activity and severely impaired the ability of the MAT(alpha)1 subunits to form homodimers essential for optimal catalytic activity. On the other hand, when lysine was substituted for R-264 (R264K), the mutant alpha1 subunit was able to form dimers that retain significant MAT activity, suggesting that amino acid 264 is involved in intersubunit salt-bridge formation. Cotransfection studies show that R264/R264H MAT(alpha)1 heterodimers are enzymatically inactive, thus providing an explanation for the R264H-mediated dominant inheritance of Hypermethioninemia.
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demyelination of the brain is associated with methionine adenosyltransferase i iii deficiency
Journal of Clinical Investigation, 1996Co-Authors: Margaret E Chamberlin, Tsuneyuki Ubagai, S H Mudd, W G Wilson, J V Leonard, Janice Yang ChouAbstract:Individuals deficient in hepatic methionine adenosyltransferase (MAT) activity (MAT I/III deficiency) have been demonstrated to contain mutations in the gene (MATA1) that encodes the major hepatic forms, MAT I and III. MAT I/III deficiency is characterized by isolated persistent Hypermethioninemia and, in some cases, unusual breath odor. Most individuals with isolated Hypermethioninemia have been free of major clinical difficulties. Therefore a definitive diagnosis of MAT I/III deficiency, which requires hepatic biopsy, is not routinely made. However, two individuals with isolated Hypermethioninemia have developed abnormal neurological problems, including brain demyelination, suggesting that MAT I/III deficiency can be deleterious. In the present study we have examined the MATA1 gene of eight hypermethioninemic individuals, including the two with demyelination of the brain. Mutations that abolish or reduce the MAT activity were detected in the MATA1 gene of all eight individuals. Both patients with demyelination are homozygous for mutations that alter the reading frame of the encoded protein such that the predicted MATalpha1 subunits are truncated and enzymatically inactive. The product of MAT, S-adenosylmethionine (AdoMet), is the major methyl donor for a large number of biologically important compounds including the two major myelin phospholipids, phosphatidylcholine and sphingomyelin. Both are synthesized primarily in the liver. Our findings demonstrate that isolated persistent Hypermethioninemia is a marker of MAT I/III deficiency, and that complete lack of MAT I/III activity can lead to neurological abnormalities. Therefore, a DNA-based diagnosis should be performed for individuals with isolated Hypermethioninemia to assess if therapy aimed at the prevention of neurological manifestations is warranted.
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molecular mechanisms of an inborn error of methionine pathway methionine adenosyltransferase deficiency
Journal of Clinical Investigation, 1995Co-Authors: Tsuneyuki Ubagai, Kejian Lei, S Huang, S H Mudd, Harvey L Levy, Janice Yang ChouAbstract:Methionine adenosyltransferase (MAT) is a key enzyme in transmethylation, transsulfuration, and the biosynthesis of polyamines. Genetic deficiency of alpha/beta-MAT causes isolated persistent Hypermethioninemia and, in some cases, unusual breath odor or neural demyelination. However, the molecular mechanism(s) underlying this deficiency has not been clearly defined. In this study, we characterized the human alpha/beta-MAT transcription unit and identified several mutations in the gene of patients with enzymatically confirmed diagnosis of MAT deficiency. Site-directed mutagenesis and transient expression assays demonstrated that these mutations partially inactivate MAT activity. These results establish the molecular basis of this disorder and allow for the development of DNA-based methodologies to investigate and diagnose hypermethioninemic individuals suspected of having abnormalities at this locus.
Thomas H Zytkovicz - One of the best experts on this subject based on the ideXlab platform.
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tandem mass spectrometric analysis for amino organic and fatty acid disorders in newborn dried blood spots a two year summary from the new england newborn screening program
Clinical Chemistry, 2001Co-Authors: Thomas H Zytkovicz, Eileen F Fitzgerald, Deborah Marsden, Cecilia Larson, Vivian E Shih, Donna M Johnson, Arnold W Strauss, Anne Marie Comeau, Roger B Eaton, George F GradyAbstract:BACKGROUND: Tandem mass spectrometry (MS/MS) is rapidly being adopted by newborn screening programs to screen dried blood spots for >20 markers of disease in a single assay. Limited information is available for setting the marker cutoffs and for the resulting positive predictive values. METHODS: We screened >160 000 newborns by MS/MS. The markers were extracted from blood spots into a methanol solution with deuterium-labeled internal standards and then were derivatized before analysis by MS/MS. Multiple reaction monitoring of each sample for the markers of interest was accomplished in approximately 1.9 min. Cutoffs for each marker were set at 6-13 SD above the population mean. RESULTS: We identified 22 babies with amino acid disorders (7 phenylketonuria, 11 hyperphenylalaninemia, 1 maple syrup urine disease, 1 Hypermethioninemia, 1 arginosuccinate lyase deficiency, and 1 argininemia) and 20 infants with fatty and organic acid disorders (10 medium-chain acyl-CoA dehydrogenase deficiencies, 5 presumptive short-chain acyl-CoA dehydrogenase deficiencies, 2 propionic acidemias, 1 carnitine palmitoyltransferase II deficiency, 1 methylcrotonyl-CoA carboxylase deficiency, and 1 presumptive very-long chain acyl-CoA dehydrogenase deficiency). Approximately 0.3% of all newborns screened were flagged for either amino acid or acylcarnitine markers; approximately one-half of all the flagged infants were from the 5% of newborns who required neonatal intensive care or had birth weights <1500 g. CONCLUSIONS: In screening for 23 metabolic disorders by MS/MS, an mean positive predictive value of 8% can be achieved when using cutoffs for individual markers determined empirically on newborns.
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tandem mass spectrometric analysis for amino organic and fatty acid disorders in newborn dried blood spots a two year summary from the new england newborn screening program
Clinical Chemistry, 2001Co-Authors: Thomas H Zytkovicz, Eileen F Fitzgerald, Vivian E Shih, Arnold W Strauss, Anne Marie Comeau, Deborah Marsde, Cecilia Larso, Donna M Johnso, Roge Eato, George F GradyAbstract:Background: Tandem mass spectrometry (MS/MS) is rapidly being adopted by newborn screening programs to screen dried blood spots for >20 markers of disease in a single assay. Limited information is available for setting the marker cutoffs and for the resulting positive predictive values. Methods: We screened >160 000 newborns by MS/MS. The markers were extracted from blood spots into a methanol solution with deuterium-labeled internal standards and then were derivatized before analysis by MS/MS. Multiple reaction monitoring of each sample for the markers of interest was accomplished in ∼1.9 min. Cutoffs for each marker were set at 6–13 SD above the population mean. Results: We identified 22 babies with amino acid disorders (7 phenylketonuria, 11 hyperphenylalaninemia, 1 maple syrup urine disease, 1 Hypermethioninemia, 1 arginosuccinate lyase deficiency, and 1 argininemia) and 20 infants with fatty and organic acid disorders (10 medium-chain acyl-CoA dehydrogenase deficiencies, 5 presumptive short-chain acyl-CoA dehydrogenase deficiencies, 2 propionic acidemias, 1 carnitine palmitoyltransferase II deficiency, 1 methylcrotonyl-CoA carboxylase deficiency, and 1 presumptive very-long chain acyl-CoA dehydrogenase deficiency). Approximately 0.3% of all newborns screened were flagged for either amino acid or acylcarnitine markers; approximately one-half of all the flagged infants were from the 5% of newborns who required neonatal intensive care or had birth weights <1500 g. Conclusions: In screening for 23 metabolic disorders by MS/MS, an mean positive predictive value of 8% can be achieved when using cutoffs for individual markers determined empirically on newborns.
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Tandem Mass Spectrometric Analysis for Amino, Organic, and Fatty Acid Disorders in Newborn Dried Blood Spots: A Two-Year Summary from the New England Newborn Screening Program
2001Co-Authors: Thomas H Zytkovicz, Eileen F Fitzgerald, Deborah Marsden, Vivian E Shih, Donna M Johnson, Arnold W Strauss, Anne Marie Comeau, Cecilia A. Larson, Roger B EatonAbstract:Background: Tandem mass spectrometry (MS/MS) is rapidly being adopted by newborn screening programs to screen dried blood spots for>20 markers of disease in a single assay. Limited information is available for setting the marker cutoffs and for the resulting positive predictive values. Methods: We screened>160 000 newborns by MS/MS. The markers were extracted from blood spots into a methanol solution with deuterium-labeled internal standards and then were derivatized before analysis by MS/MS. Multiple reaction monitoring of each sample for the markers of interest was accomplished in �1.9 min. Cutoffs for each marker were set at 6–13 SD above the population mean. Results: We identified 22 babies with amino acid disorders (7 phenylketonuria, 11 hyperphenylalaninemia, 1 maple syrup urine disease, 1 Hypermethioninemia, 1 arginosuccinate lyase deficiency, and 1 argininemia) and 20 infants with fatty and organic acid disorders (10 medium-chain acyl-CoA dehydrogenase deficiencies, 5 presumptive short-chain acyl-CoA dehydrogenase deficiencies, 2 propionic acidemias, 1 carnitine palmitoyltransferase II deficiency, 1 methylcrotonyl-CoA carboxylase deficiency, and 1 presumptive very-long chain