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Kido J, Sugawara K, Sawada T, Matsumoto S, Nakamura K. Pathogenic variants of ornithine transcarbamylase deficiency: Nation-wide study in Japan and literature review. Front Genet 2022; 13:952467. [PMID: 36303552 PMCID: PMC9593096 DOI: 10.3389/fgene.2022.952467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 08/25/2022] [Indexed: 11/29/2022] Open
Abstract
Ornithine transcarbamylase deficiency (OTCD) is an X-linked disorder. Several male patients with OTCD suffer from severe hyperammonemic crisis in the neonatal period, whereas others develop late-onset manifestations, including hyperammonemic coma. Females with heterozygous pathogenic variants in the OTC gene may develop a variety of clinical manifestations, ranging from asymptomatic conditions to severe hyperammonemic attacks, owing to skewed lyonization. We reported the variants of CPS1, ASS, ASL and OTC detected in the patients with urea cycle disorders through a nation-wide survey in Japan. In this study, we updated the variant data of OTC in Japanese patients and acquired information regarding genetic variants of OTC from patients with OTCD through an extensive literature review. The 523 variants included 386 substitution (330 missense, 53 nonsense, and 3 silent), eight deletion, two duplication, one deletion-insertion, 55 frame shift, two extension, and 69 no category (1 regulatory and 68 splice site error) mutations. We observed a genotype-phenotype relation between the onset time (neonatal onset or late onset), the severity, and genetic mutation in male OTCD patients because the level of deactivation of OTC significantly depends on the pathogenic OTC variants. In conclusion, genetic information about OTC may help to predict long-term outcomes and determine specific treatment strategies, such as liver transplantation, in patients with OTCD.
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Affiliation(s)
- Jun Kido
- Department of Pediatrics, Kumamoto University Hospital, Kumamoto, Japan
- Department of Pediatrics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Keishin Sugawara
- Department of Pediatrics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Takaaki Sawada
- Department of Pediatrics, Kumamoto University Hospital, Kumamoto, Japan
- Department of Pediatrics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Shirou Matsumoto
- Department of Pediatrics, Kumamoto University Hospital, Kumamoto, Japan
- Department of Pediatrics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Kimitoshi Nakamura
- Department of Pediatrics, Kumamoto University Hospital, Kumamoto, Japan
- Department of Pediatrics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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Gobin-Limballe S, Ottolenghi C, Reyal F, Arnoux JB, Magen M, Simon M, Brassier A, Jabot-Hanin F, Lonlay PD, Pontoizeau C, Guirat M, Rio M, Gesny R, Gigarel N, Royer G, Steffann J, Munnich A, Bonnefont JP. OTC deficiency in females: Phenotype-genotype correlation based on a 130-family cohort. J Inherit Metab Dis 2021; 44:1235-1247. [PMID: 34014569 DOI: 10.1002/jimd.12404] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 12/30/2022]
Abstract
OTC deficiency, an inherited urea cycle disorder, is caused by mutations in the X-linked OTC gene. Phenotype-genotype correlations are well understood in males but still poorly known in females. Taking advantage of a cohort of 130 families (289 females), we assessed the relative contribution of OTC enzyme activity, X chromosome inactivation, and OTC gene sequencing to genetic counseling in heterozygous females. Twenty two percent of the heterozygous females were clinically affected, with episodic (11%), chronic (7.5%), or neonatal forms of the disease (3.5%). Overall mortality rate was 4%. OTC activity, ranging from 0% to 60%, did not correlate with phenotype at the individual level. Analysis of multiple samples from 4 mutant livers showed intra-hepatic variability of OTC activity and X inactivation profile (range of variability: 30% and 20%, respectively) without correlation between both parameters for 3 of the 4 livers. Ninety disease-causing variants were found, 27 of which were novel. Mutations were classified as "mild" or "severe," based on male phenotypes and/or in silico prediction. In our cohort, a serious disease occurred in 32% of females with a severe mutation, compared to 4% in females with a mild mutation (odds ratio = 1.365; P = 1.6e-06). These data should help prenatal diagnosis for heterozygous females and genetic counseling after fortuitous findings of OTC variants in pangenomic sequencing.
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Affiliation(s)
| | - Chris Ottolenghi
- Metabolomic and Proteomic Biochemistry Department, Necker Hospital, APHP Centre- Paris University, Paris, France
- INSERM UMR1163, Institut Imagine, Paris University, Paris, France
| | - Fabien Reyal
- Molecular Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
- Breast Gynecologic Cancer Reconstructive Team, Institut Curie, Paris University, Paris, France
| | - Jean-Baptiste Arnoux
- Inherited Metabolic Disease Department and National Reference Centre for Inherited Metabolic diseases, Necker Hospital, APHP Centre-Paris University, Paris, France
- INSERM U1151, INEM, Paris University, Paris, France
| | - Maryse Magen
- Molecular Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
| | - Marie Simon
- Molecular Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
| | - Anaïs Brassier
- Inherited Metabolic Disease Department and National Reference Centre for Inherited Metabolic diseases, Necker Hospital, APHP Centre-Paris University, Paris, France
- INSERM U1151, INEM, Paris University, Paris, France
| | - Fabienne Jabot-Hanin
- Bioinformatics Platform, Paris University, INSERM UMR1163, Institut Imagine, Paris, France
- Structure Federative de Recherche Necker, INSERM US24/CNRS UMS3633, Paris, France
| | - Pascale De Lonlay
- Inherited Metabolic Disease Department and National Reference Centre for Inherited Metabolic diseases, Necker Hospital, APHP Centre-Paris University, Paris, France
- INSERM U1151, INEM, Paris University, Paris, France
| | - Clement Pontoizeau
- Metabolomic and Proteomic Biochemistry Department, Necker Hospital, APHP Centre- Paris University, Paris, France
- INSERM UMR1163, Institut Imagine, Paris University, Paris, France
| | - Manel Guirat
- Molecular Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
| | - Marlene Rio
- Clinical Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
| | - Roselyne Gesny
- Molecular Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
| | - Nadine Gigarel
- Molecular Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
| | - Ghislaine Royer
- Molecular Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
| | - Julie Steffann
- Molecular Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
- INSERM UMR1163, Institut Imagine, Paris University, Paris, France
| | - Arnold Munnich
- INSERM UMR1163, Institut Imagine, Paris University, Paris, France
- Clinical Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
| | - Jean-Paul Bonnefont
- Molecular Genetics Department, Necker Hospital, APHP Centre-Paris University, Paris, France
- INSERM UMR1163, Institut Imagine, Paris University, Paris, France
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Alsharhan H, Alharbi H, Priestley J, Ganetzky R, He M. Urinary Uracil: A Useful Marker for Ornithine Transcarbamylase Deficiency in Affected Males. Clin Chem 2021; 66:988-989. [PMID: 32628763 DOI: 10.1093/clinchem/hvaa101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/09/2020] [Indexed: 11/14/2022]
Affiliation(s)
- Hind Alsharhan
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA.,Division of Human Genetics, Section of Biochemical Genetics, Children's Hospital of Philadelphia, PA.,Department of Pediatrics, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Hana Alharbi
- Division of Human Genetics, Section of Biochemical Genetics, Children's Hospital of Philadelphia, PA
| | - Jessica Priestley
- Division of Human Genetics, Section of Biochemical Genetics, Children's Hospital of Philadelphia, PA
| | - Rebecca Ganetzky
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA.,Division of Human Genetics, Section of Biochemical Genetics, Children's Hospital of Philadelphia, PA.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Miao He
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA
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Laemmle A, Gallagher RC, Keogh A, Stricker T, Gautschi M, Nuoffer JM, Baumgartner MR, Häberle J. Frequency and Pathophysiology of Acute Liver Failure in Ornithine Transcarbamylase Deficiency (OTCD). PLoS One 2016; 11:e0153358. [PMID: 27070778 PMCID: PMC4829252 DOI: 10.1371/journal.pone.0153358] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 03/29/2016] [Indexed: 12/13/2022] Open
Abstract
Background Acute liver failure (ALF) has been reported in ornithine transcarbamylase deficiency (OTCD) and other urea cycle disorders (UCD). The frequency of ALF in OTCD is not well-defined and the pathogenesis is not known. Aim To evaluate the prevalence of ALF in OTCD, we analyzed the Swiss patient cohort. Laboratory data from 37 individuals, 27 females and 10 males, diagnosed between 12/1991 and 03/2015, were reviewed for evidence of ALF. In parallel, we performed cell culture studies using human primary hepatocytes from a single patient treated with ammonium chloride in order to investigate the inhibitory potential of ammonia on hepatic protein synthesis. Results More than 50% of Swiss patients with OTCD had liver involvement with ALF at least once in the course of disease. Elevated levels of ammonia often correlated with (laboratory) coagulopathy as reflected by increased values for international normalized ratio (INR) and low levels of hepatic coagulation factors which did not respond to vitamin K. In contrast, liver transaminases remained normal in several cases despite massive hyperammonemia and liver involvement as assessed by pathological INR values. In our in vitro studies, treatment of human primary hepatocytes with ammonium chloride for 48 hours resulted in a reduction of albumin synthesis and secretion by approximately 40%. Conclusion In conclusion, ALF is a common complication of OTCD, which may not always lead to severe symptoms and may therefore be underdiagnosed. Cell culture experiments suggest an ammonia-induced inhibition of hepatic protein synthesis, thus providing a possible pathophysiological explanation for hyperammonemia-associated ALF.
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Affiliation(s)
- Alexander Laemmle
- Division of Metabolism and Children`s Research Center (CRC), University Children`s Hospital, Zurich, Switzerland
- radiz–Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Zurich, Switzerland
- * E-mail: ;
| | - Renata C. Gallagher
- Department of Pediatrics, Medical Genetics, University of California San Francisco, San Francisco, United States of America
| | - Adrian Keogh
- Department of Clinical Research and Clinic for Visceral Surgery and Medicine, Bern University Hospital, Bern, Switzerland
| | - Tamar Stricker
- Division of Metabolism and Children`s Research Center (CRC), University Children`s Hospital, Zurich, Switzerland
| | - Matthias Gautschi
- Department of Pediatrics, University Children's Hospital, Bern, Switzerland
- University Institute of Clinical Chemistry, University of Bern, Bern, Switzerland
| | - Jean-Marc Nuoffer
- Department of Pediatrics, University Children's Hospital, Bern, Switzerland
- University Institute of Clinical Chemistry, University of Bern, Bern, Switzerland
| | - Matthias R. Baumgartner
- Division of Metabolism and Children`s Research Center (CRC), University Children`s Hospital, Zurich, Switzerland
- radiz–Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Johannes Häberle
- Division of Metabolism and Children`s Research Center (CRC), University Children`s Hospital, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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Functional characterization of the spf/ash splicing variation in OTC deficiency of mice and man. PLoS One 2015; 10:e0122966. [PMID: 25853564 PMCID: PMC4390381 DOI: 10.1371/journal.pone.0122966] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 02/16/2015] [Indexed: 12/27/2022] Open
Abstract
The spf/ash mouse model of ornithine transcarbamylase (OTC) deficiency, a severe urea cycle disorder, is caused by a mutation (c.386G>A; p.R129H) in the last nucleotide of exon 4 of the Otc gene, affecting the 5' splice site and resulting in partial use of a cryptic splice site 48 bp into the adjacent intron. The equivalent nucleotide change and predicted amino acid change is found in OTC deficient patients. Here we have used liver tissue and minigene assays to dissect the transcriptional profile resulting from the "spf/ash" mutation in mice and man. For the mutant mouse, we confirmed liver transcripts corresponding to partial intron 4 retention by the use of the c.386+48 cryptic site and to normally spliced transcripts, with exon 4 always containing the c.386G>A (p.R129H) variant. In contrast, the OTC patient exhibited exon 4 skipping or c.386G>A (p.R129H)-variant exon 4 retention by using the natural or a cryptic splice site at nucleotide position c.386+4. The corresponding OTC tissue enzyme activities were between 3-6% of normal control in mouse and human liver. The use of the cryptic splice sites was reproduced in minigenes carrying murine or human mutant sequences. Some normally spliced transcripts could be detected in minigenes in both cases. Antisense oligonucleotides designed to block the murine cryptic +48 site were used in minigenes in an attempt to redirect splicing to the natural site. The results highlight the relevance of in depth investigations of the molecular mechanisms of splicing mutations and potential therapeutic approaches. Notably, they emphasize the fact that findings in animal models may not be applicable for human patients due to the different genomic context of the mutations.
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Lee JH, Kim GH, Yoo HW, Cheon CK. OTC gene in ornithine transcarbamylase deficiency: clinical course and mutational spectrum in seven Korean patients. Pediatr Neurol 2014; 51:354-359.e1. [PMID: 25011434 DOI: 10.1016/j.pediatrneurol.2014.03.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Revised: 02/27/2014] [Accepted: 03/03/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Ornithine transcarbamylase deficiency, an inborn error of metabolism, is the most common urea cycle disorder and is caused by mutations in the OTC gene located on Xp21. In this study, the clinical and genetic characteristics of seven Korean patients with ornithine transcarbamylase deficiency were analyzed. METHODS During 2009-2012, a total of seven patients (three male and four female patients) from six unrelated families were diagnosed with ornithine transcarbamylase deficiency by biochemical or molecular analysis. OTC gene sequencing analysis was performed in six of these patients. Clinical manifestations, clinical courses, and the results of genetic studies were reviewed retrospectively. RESULTS The median follow-up period for the seven patients with ornithine transcarbamylase deficiency was 44 months (11.9-150 months). Clinical manifestations of ornithine transcarbamylase deficiency included vomiting and seizure, which were the most frequent signs at admission. Two of the four heterozygous female patients (50%) experienced severe neurological sequelae. The early onset male patient characterized severe neurological deficits. The late-onset male patient recovered completely from acute encephalopathy and coma without any neurological deficits. Direct sequencing and multiplex ligation-dependent probe amplification analysis of OTC gene revealed five different mutations. Of these mutations, two were novel (c.867-3T>C and c.664_667delinsAC). CONCLUSION Ornithine transcarbamylase deficiency was genetically heterogeneous in the seven Korean patients with confirmed ornithine transcarbamylase deficiency diagnosis by biochemical findings and/or genetic analysis, together with two novel mutations in the OTC gene. We hope that these data will contribute to a better understanding of the clinical course and distinct molecular genetic characteristics of Korean patients with ornithine transcarbamylase deficiency.
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Affiliation(s)
- Jung Hyun Lee
- Department of Pediatrics, Kosin University Gospel Hospital, Busan, South Korea
| | - Gu-Hwan Kim
- Department of Pediatrics, Medical Genetics Clinic and Laboratory, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, South Korea
| | - Han-Wook Yoo
- Department of Pediatrics, Medical Genetics Clinic and Laboratory, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, South Korea
| | - Chong-Kun Cheon
- Department of Pediatrics, Pediatric Genetics and Metabolism, Pusan National University Children's Hospital, Pusan National University School of Medicine, Yangsan, South Korea; Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, South Korea.
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7
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Shchelochkov OA, Li FY, Geraghty MT, Gallagher RC, Van Hove JL, Lichter-Konecki U, Fernhoff PM, Copeland S, Reimschisel T, Cederbaum S, Lee B, Chinault AC, Wong LJ. High-frequency detection of deletions and variable rearrangements at the ornithine transcarbamylase (OTC) locus by oligonucleotide array CGH. Mol Genet Metab 2009; 96:97-105. [PMID: 19138872 DOI: 10.1016/j.ymgme.2008.11.167] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 11/23/2008] [Accepted: 11/25/2008] [Indexed: 01/29/2023]
Abstract
Ornithine transcarbamylase (OTC) deficiency is an X-linked inborn error of metabolism characterized by impaired synthesis of citrulline from carbamylphosphate and ornithine. Previously reported data suggest that only approximately 80% of OTC deficiency (OTCD) patients have a mutation identified by OTC gene sequencing. To elucidate the molecular etiology in patients with clinical signs of OTCD and negative OTC sequencing, we subjected their DNA to array comparative genomic hybridization (aCGH) using a custom-designed targeted 44k oligonucleotide array. Whenever possible, parental DNA was analyzed to determine the inheritance or to rule out copy number variants in the OTC locus. DNA samples from a total of 70 OTCD patients were analyzed. Forty-three patients (43/70 or 61.5%) were found to have disease-causing point mutations in the OTC gene. The remaining 27 patients (27/70 or 38.5%) showed normal sequencing results or failure to amplify all or part of the OTC gene. Among those patients, eleven (11/70 or 15.7%) were found to have deletions ranging from 4.5kb to 10.6Mb, all involving the OTC gene. Sixteen OTCD patients (16/70 or 22.8%) had normal sequencing and oligoarray results. Analysis of the deletions did not reveal shared breakpoints, suggesting that non-homologous end joining or a replication-based mechanism might be responsible for the formation of the observed rearrangements. In summary, we demonstrate that approximately half of the patients with negative OTC sequencing may have OTC gene deletions readily identifiable by the targeted oligonucleotide-based aCGH. Thus, the test should be considered in OTC sequencing-negative patients with classic symptoms of the disease.
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Affiliation(s)
- Oleg A Shchelochkov
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Yamaguchi S, Brailey LL, Morizono H, Bale AE, Tuchman M. Mutations and polymorphisms in the human ornithine transcarbamylase (OTC) gene. Hum Mutat 2006; 27:626-32. [PMID: 16786505 DOI: 10.1002/humu.20339] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Ornithine transcarbamylase (OTC) deficiency is the most common inherited disorder of the urea cycle and is transmitted as an X-linked trait. Defects in the OTC gene cause a block in ureagenesis resulting in hyperammonemia, which can lead to brain damage and death. Three previous mutation updates for the OTC gene have been published, in 1993, 1995, and 2002. The most recent comprehensive update, in 2002, contained 244 mutations including 13 nondisease-causing mutations and polymorphisms. This current update reports 341 mutations, of which 93 have not been previously reported, and an additional 29 nondisease-causing mutations and polymorphisms. Out of the 341 mutations, 149 were associated with neonatal onset of hyperammonemia (within the first week of life), 70 were seen in male patients with later onset of hyperammonemia, and 121 were found in heterozygous females (one unknown). Along with the reported mutations, residual enzyme activities and other pertinent clinical information are included whenever available. Most mutations in the OTC gene are specific to a particular family ("private" mutations). They are distributed throughout the gene, with a significant paucity of mutations in the 32 first codons encoding the "leader" peptide (exon 1 and the beginning of exon 2). Almost all mutations in consensus splice sites confer a neonatal onset phenotype. Using the current molecular screening methods, mutations are found in about 80% of the patients. The remaining patients may have mutations in regulatory domains or mutations deep in the introns, which constitute 98.5% of the genomic sequence. In addition, a phenocopy of OTC deficiency caused by mutations in another unknown gene cannot be excluded.
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Affiliation(s)
- Saori Yamaguchi
- College of Life Science, University of Maryland, College Park, Maryland, USA
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Tuchman M, Jaleel N, Morizono H, Sheehy L, Lynch MG. Mutations and polymorphisms in the human ornithine transcarbamylase gene. Hum Mutat 2002; 19:93-107. [PMID: 11793468 DOI: 10.1002/humu.10035] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ornithine transcarbamylase (OTC) deficiency, an X-linked, semidominant disorder, is the most common inherited defect in ureagenesis resulting in hyperammonemia. The previous two mutation updates for the OTC gene were published in 1993 and 1995 and included 36 and 30 mutations respectively. This comprehensive update contains a compilation of 244 mutations including 13 polymorphisms. Twenty-four of the mutations are reported here for the first time. Forty-two percent of the disease-causing mutations are associated with acute neonatal hyperammonemia; 21% were found in patients with late onset disease and approximately 37% were found in manifesting heterozygous females, most of which are presumed to confer a neonatal phenotype in hemizygous males. Also included are residual enzyme activities and residual incorporation of ammonium nitrogen into urea and results of expression studies for a small proportion of the mutations. Most mutations in the OTC gene are "private" and are distributed throughout the gene with paucity of mutation in the sequence encoding the leader peptide (exon 1 and beginning of exon 2) and in exon 7. Almost all mutations in consensus splicing sites confer a neonatal phenotype. Thirteen polymorphisms have been found, several of which are useful for allele tracking in patients in whom the mutation can't be found. Even with sequencing of the entire reading frame and exon/intron boundaries, only about 80% of the mutations are detected in patients with proven OTC deficiency. The remaining probably occur within the introns or in regulatory domains.
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Affiliation(s)
- Mendel Tuchman
- Children's Research Institute, Children's National Medical Center, George Washington University, Washington DC, USA
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Shimadzu M, Matsumoto H, Matsuura T, Kobayashi K, Komaki S, Kiwaki K, Hoshide R, Endo F, Saheki T, Matsuda I. Ten novel mutations of the ornithine transcarbamylase (OTC) gene in OTC deficiency. Hum Mutat 1998; Suppl 1:S5-7. [PMID: 9452024 DOI: 10.1002/humu.1380110103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- M Shimadzu
- Department of Genetics, Mitsubishi Kagaku Bio-clinical Laboratories, Itabashi, Shimura, Japan
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Hoshide R, Matsuura T, Sagara Y, Kubo T, Shimadzu M, Endo F, Matsuda I. Prenatal monitoring in a family at high risk for ornithine transcarbamylase (OTC) deficiency: a new mutation of an A-to-C transversion in position +4 of intron 1 of the OTC gene that is likely to abolish enzyme activity. AMERICAN JOURNAL OF MEDICAL GENETICS 1996; 64:459-64. [PMID: 8862622 DOI: 10.1002/(sici)1096-8628(19960823)64:3<459::aid-ajmg3>3.0.co;2-k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
DNA analysis of a male propositus with ornithine transcarbamylase (OTC) deficiency documented an A-to-C substitution in position +4 of intron 1. No other abnormalities were observed in the OTC gene, or at 563 bp upstream of the 5' site, which included a promoter region, or at 383 bp downstream of the termination codon, which included a polyadenylation signal sequence. This mutation produces an RsaI site in the sequence, which was used for prenatal monitoring in the fourth and fifth pregnancies. DNA from amniotic cells in the former case were positive for RsaI digestion and the SRY gene (sex determinant region Y), indicating hemizygosity for the mutant allele. OTC activity was not measurable, and mRNA of the OTC gene was not detected by Northern blotting in the affected fetal liver. RT-PCR (reverse transcription-PCR) demonstrated only the wild-type allele. Thus, the mutation interferes with RNA processing, and an extremely low amount of normally spliced mRNA for the OTC gene seems to have caused the disease in our patient. The fetus of the fifth pregnancy was a normal male, as confirmed postnatally.
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Affiliation(s)
- R Hoshide
- Department of Pediatrics, Kumamoto University School of Medicine, Japan
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Matsuda I, Matsuura T, Nishiyori A, Komaki S, Hoshide R, Matsumoto T, Funakoshi M, Kiwaki K, Endo F, Hata A, Shimadzu M, Yoshino M. Phenotypic variability in male patients carrying the mutant ornithine transcarbamylase (OTC) allele, Arg40His, ranging from a child with an unfavourable prognosis to an asymptomatic older adult. J Med Genet 1996; 33:645-8. [PMID: 8863155 PMCID: PMC1050697 DOI: 10.1136/jmg.33.8.645] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In five different Japanese families, we identified six male hemizygotes (aged 6, 9, 15, 17, 56, and 65 years) and a putative candidate (aged 48 years), carrying a mutant allele of the ornithine transcarbamylase (OTC) gene, a G to A substitution at nucleotide 119 in exon 2 generating histidine in place of arginine. OTC activity in the necropsied liver tissue was reduced to approximately 12% of the control and that of COS 1 cells transfected with Arg40His OTC cDNA was 10.2 +/- 1.8% of the control transfected with wild type OTC cDNA. Clinical features ranged from death during a hyperammonaemic attack (a 9 year old) to a 65 year old asymptomatic man. We consider that the amount of protein ingested by these subjects may be one predisposing factor leading to the manifestation of this disease.
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Affiliation(s)
- I Matsuda
- Department of Paediatrics, School of Medicine, Kumamoto University, Japan
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14
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Oppliger Leibundgut E, Wermuth B, Colombo JP, Liechti-Gallati S. Identification of four novel splice site mutations in the ornithine transcarbamylase gene. Hum Genet 1996; 97:209-13. [PMID: 8566955 DOI: 10.1007/bf02265267] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Ornithine transcarbamylase (OTC) deficiency, the most common inborn error of the urea cycle, shows X-linked inheritance with frequent new mutations. Using polymerase chain reaction (PCR) amplification of the individual exons including adjacent intron sequences followed by direct sequencing of the amplimers we identified four new mutations affecting donor splice sites of introns 2, 5, 6, and 8. The mutation at the first position of intron 2 was a G to A exchange associated with acute neonatal hyperammonemia in a male patient at the age of 5 months. A G to C substitution in intron 5 was detected in a boy who developed 2 days after birth hypotonia, and respiratory distress, followed by severe hyperammonemia and terminal coma. The intron 6 mutation, a G to T substitution, was detected in a girl presenting with first episodes of vomiting and agitation at the age of 2 months. The mutation in intron 8, also a G to T transition, caused fatal hyperammonemia and early death at the age of 15 days in a male patient. We present four donor splice site mutations resulting in severe neonatal or very early onset of the disease in three boys and in one female patient. As the GT dinucleotide of the 5' donor splice site is invariant and required for correct splicing the described mutations may lead to improperly spliced mRNAs and aberrant gene products.
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Oppliger Leibundgut EO, Wermuth B, Colombo JP, Liechti-Gallati S. Ornithine transcarbamylase deficiency: characterization of gene mutations and polymorphisms. Hum Mutat 1996; 8:333-9. [PMID: 8956038 DOI: 10.1002/(sici)1098-1004(1996)8:4<333::aid-humu6>3.0.co;2-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We identified three new and three known mutations in male patients with OTC deficiency using PCR amplification of all the individual exons, including the adjacent intron sequences, followed by direct sequencing of the amplimers. Two mutations were found in males presenting with neonatal fatal hyperammonemia and no detectable enzyme activity in their livers. The H302Y mutation found in one patient affects the putative binding site for ornithine. The second patient had an R141X mutation, which is one of the few recurrent mutations in the OTC gene. Four different missense mutations were identified in male patients with late onset of the disease and residual OTC activities between 14% and 35%. The mutations are Y176C and P220A and the known mutations K88N and T343K, respectively. Four of the patients' mothers were identified as carriers. In two cases, the mutations had occurred spontaneously. In addition, the frequency of four polymorphisms of the OTC gene was studied. The K46R polymorphism in exon 2 and the Q27OR polymorphism in exon 8 were found in 36% and 4% of screened alleles, respectively. Two questionable polymorphisms in exon 4, F101L and L111P, were not present in any of the screened alleles.
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Gilbert-Dussardier B, Segues B, Rozet JM, Rabier D, Calvas P, de Lumley L, Bonnefond JP, Munnich A. Partial duplication [dup. TCAC (178)] and novel point mutations (T125M, G188R, A209V, and H302L) of the ornithine transcarbamylase gene in congenital hyperammonemia. Hum Mutat 1996; 8:74-6. [PMID: 8807340 DOI: 10.1002/(sici)1098-1004(1996)8:1<74::aid-humu11>3.0.co;2-o] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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