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Abadingo ME, Abacan MAR, Basas JRU, Padilla CD. Pregnancy in an adolescent with maple syrup urine disease: Case report. Mol Genet Metab Rep 2021; 27:100745. [PMID: 33868929 PMCID: PMC8042167 DOI: 10.1016/j.ymgmr.2021.100745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/07/2021] [Accepted: 03/09/2021] [Indexed: 11/27/2022] Open
Abstract
Maple syrup urine disease (MSUD, MIM #248600) is an autosomal recessive metabolic disorder that results in elevation of the branched-chain amino acids (BCAA) leucine, isoleucine, and valine. Elevation of BCAA and certain alpha keto-acids is associated with a catabolic state and may result in neurological and developmental delays, feeding problems, and a urine and cerumen odor of maple syrup. Pregnancy is a period of multiple adaptations necessary to support fetal growth and development. Both the third trimester of pregnancy and the postpartum period present the possibility for catabolic states. We describe our treatment of an adolescent patient with intermittent MSUD and her resulting positive pregnancy outcome.
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Affiliation(s)
- Michelle E Abadingo
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of the Philippines - Philippine General Hospital, Manila, Philippines.,Institute of Human Genetics, National Institutes of Health, University of the Philippines, Manila, Philippines.,Newborn Screening Reference Center, National Institutes of Health, University of the Philippines, Manila, Philippines
| | - Mary Ann R Abacan
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of the Philippines - Philippine General Hospital, Manila, Philippines.,Institute of Human Genetics, National Institutes of Health, University of the Philippines, Manila, Philippines
| | - Jeanne Ruth U Basas
- Institute of Human Genetics, National Institutes of Health, University of the Philippines, Manila, Philippines
| | - Carmencita D Padilla
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, University of the Philippines - Philippine General Hospital, Manila, Philippines.,Institute of Human Genetics, National Institutes of Health, University of the Philippines, Manila, Philippines.,Newborn Screening Reference Center, National Institutes of Health, University of the Philippines, Manila, Philippines
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Ma S, Zhang Z, Fu Y, Zhang M, Niu Y, Li R, Guo Q, He Z, Zhao Q, Song Z, Wang X, Sun R. Identification of the first Alu-mediated gross deletion involving the BCKDHA gene in a compound heterozygous patient with maple syrup urine disease. Clin Chim Acta 2021; 517:23-30. [PMID: 33607070 DOI: 10.1016/j.cca.2021.01.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 01/31/2021] [Accepted: 01/31/2021] [Indexed: 11/25/2022]
Abstract
AIMS To investigate a family with clinical symptoms of maple syrup urine disease and reveal a genetic cause underlying this disease. METHODS Targeted capture sequencing was used to screen for mutations in the patient. Real-Time PCR was carried out to perform exon 1, 5, 9 CNV analysis of samples from the patient's father, mother and sister. Whole genome sequencing was performed to map the approximate location of the break points of the gross deletion. Long-range PCR and Sanger sequencing were performed to identify the length of the deletion and to locate the break points. RESULTS The patient is a compound heterozygous mutation including a small deletion mutation (c.1227_1229del chr19: 41930402) and a gross novel deletion including exon1-9 in BCKDHA. The junction site of the gross deletion was localized within a microhomologous sequence in two Alu elements. CONCLUSIONS This study is the first time report on rearrangement sequences in BCKDHA mediated by Alu element, which resulted in MSUD. Our results may also offer new insights into the formation and pathogenicity of MSUD, and may be useful to genetic counseling and genetic testing.
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Affiliation(s)
- Shujun Ma
- Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, School of Laboratory Medicine, Xinxiang Medical University, China; Henan Key Laboratory of Immunology and Targeted Drugs, School of Laboratory Medicine, Xinxiang Medical University, China.
| | - Zhongxin Zhang
- Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, School of Laboratory Medicine, Xinxiang Medical University, China
| | - Yanyan Fu
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang 453003, China
| | - Mingxia Zhang
- Xinxiang Maternity and Child Care Hospital, Xinxiang 453003, China
| | - Yuna Niu
- Henan Key Laboratory of Immunology and Targeted Drugs, School of Laboratory Medicine, Xinxiang Medical University, China
| | - Ruiguang Li
- Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, School of Laboratory Medicine, Xinxiang Medical University, China
| | - Qinghe Guo
- Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, School of Laboratory Medicine, Xinxiang Medical University, China
| | - Zhian He
- Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, School of Laboratory Medicine, Xinxiang Medical University, China
| | - Qingwei Zhao
- Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, School of Laboratory Medicine, Xinxiang Medical University, China
| | - Zhishan Song
- Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, School of Laboratory Medicine, Xinxiang Medical University, China
| | - Xia Wang
- Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, School of Laboratory Medicine, Xinxiang Medical University, China
| | - Ruili Sun
- Henan Key Laboratory of Immunology and Targeted Drugs, School of Laboratory Medicine, Xinxiang Medical University, China
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Nguyen TTN, Vu CD, Nguyen NL, Nguyen TTH, Nguyen NK, Nguyen HH. Identification of novel mutations in BCKDHB and DBT genes in Vietnamese patients with maple sirup urine disease. Mol Genet Genomic Med 2020; 8:e1337. [PMID: 32515140 PMCID: PMC7434729 DOI: 10.1002/mgg3.1337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 04/29/2020] [Accepted: 05/01/2020] [Indexed: 01/10/2023] Open
Abstract
Background Maple sirup urine disease (MSUD) is an autosomal recessive inherited metabolic disorder. The disease‐causing mutations can affect the BCKDHA, BCKDHB, and DBT genes encoding for the E1α, E1β, and E2 subunits of the multienzyme branched‐chain α‐keto acid dehydrogenase (BCKDH) complex. In the present study, novel pathogenic variants in BCKDHB and DBT genes were identified in three Vietnamese families with MSUD. Methods Three newborn patients from three unrelated Vietnamese families were diagnosed with MSUD at the Metabolic Clinic, National Hospital of Pediatrics. Blood samples of 11 relatives from two generations of the three families diagnosed with MSUD were analyzed using exome and Sanger sequencing analyses. Results Novel pathogenic variants in BCKDHB (c.1103C>T, c.989A>G, and c.704G>A), and DBT (c.263_265delAAG) genes were identified in three pediatric patients with MSUD. Conclusions We have identified novel pathogenic variants in the MSUD‐related genes in the pedigree of the three patient's families. Our findings expand the mutational spectrum of MSUD and provide the scientific basis for genetic counseling for the patient's families.
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Affiliation(s)
- Thi T N Nguyen
- Institute of Genome Research, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | - Chi D Vu
- National Hospital of Pediatrics, Hanoi, Vietnam
| | - Ngoc L Nguyen
- Institute of Genome Research, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam.,Graduate University of Science and Technology, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | - Thi T H Nguyen
- Institute of Genome Research, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam.,Graduate University of Science and Technology, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
| | | | - Huy H Nguyen
- Institute of Genome Research, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
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Ali EZ, Ngu LH. Fourteen new mutations of BCKDHA, BCKDHB and DBT genes associated with maple syrup urine disease (MSUD) in Malaysian population. Mol Genet Metab Rep 2018; 17:22-30. [PMID: 30228974 PMCID: PMC6140420 DOI: 10.1016/j.ymgmr.2018.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/30/2018] [Accepted: 08/30/2018] [Indexed: 12/11/2022] Open
Abstract
Maple syrup urine disease (MSUD) is a rare autosomal recessive metabolic disorder. This disorder is usually caused by mutations in any one of the genes; BCKDHA, BCKDHB and DBT, which represent E1α, E1β and E2 subunits of the branched-chain α-keto acid dehydrogenase (BCKDH) complex, respectively. This study presents the molecular characterization of 31 MSUD patients. Twenty one mutations including 14 new mutations were identified. The BCKDHB gene was the most commonly affected (45.2%) compared to BCKDHA gene (16.1%) and DBT gene (38.7%). In silico webservers predicted all mutations were disease-causing. In addition, structural evaluation disclosed that all new missenses in BCKDHA, BCKDHB and DBT genes affected stability and formation of E1 and E2 subunits. Majority of the patients had neonatal onset MSUD (26 of 31). Meanwhile, the new mutation; c.1196C > G (p.S399C) in DBT gene was noted to be recurrent and found in 9 patients. Conclusion: Our findings have expanded the mutational spectrum of the MSUD and revealed the genetic heterogeneity among Malaysian MSUD patients. We also discovered the p.S399C from DBT gene was noted as a recurrent mutation in Malay community and it suggested the existence of common and unique mutation in Malay population.
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Affiliation(s)
- Ernie Zuraida Ali
- Molecular Diagnostics and Protein Unit, Specialized Diagnostics Centre, Institute for Medical Research, Jalan Pahang, 50588 Kuala Lumpur, Malaysia
| | - Lock-Hock Ngu
- Medical Genetics Department, Kuala Lumpur Hospital, Jalan Pahang, 50588 Kuala Lumpur, Malaysia
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Hou JW. Maple Syrup Urine Disease Complicated with Kyphoscoliosis and Myelopathy. Pediatr Neonatol 2016; 57:431-435. [PMID: 24486081 DOI: 10.1016/j.pedneo.2013.10.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 10/01/2013] [Accepted: 10/22/2013] [Indexed: 11/26/2022] Open
Abstract
Maple syrup urine disease (MSUD) is an autosomal recessive aminoacidopathy secondary to an enzyme defect in the catabolic pathway of the branched-chain amino acids (BCAAs: leucine, isoleucine, and valine). Accumulation of their corresponding keto-acids leads to encephalopathy if not treated in time. A newborn male patient was suspected to have MSUD after tandem mass study when he presented symptoms and signs suggestive neonatal sepsis, anemia, and diarrhea. Food restriction of BCAAs was started; however, acrodermatitis enteropathica-like skin eruptions occurred at age 2 months. The skin rashes resolved after adding BCAAs and adjusting the infant formula. At age 7 months, he suffered from recurrent skin lesions, zinc deficiency, osteoporosis, and kyphosis of the thoracic spine with acute angulation over the T11-T12 level associated with spinal compression and myelopathy. After supplementation of zinc products and pamidronate, skin lesions and osteopenia improved gradually. Direct sequencing of the DBT gene showed a compound heterozygous mutation [4.7 kb deletion and c.650-651insT (L217F or L217fsX223)]. It is unusual that neurodegeneration still developed in this patient despite diet restriction. Additionally, brain and spinal magnetic resonance imaging, bone mineral density study, and monitoring of zinc status are suggested in MSUD patients.
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Affiliation(s)
- Jia-Woei Hou
- Department of Pediatrics, Cathay General Hospital, Taipei, Taiwan; School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan.
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Aw-Zoretic J, Wadhwani NR, Lulla RR, Ryan ME. Imaging findings of anaplastic astrocytoma in a child with maple syrup urine disease: a case report. Childs Nerv Syst 2015; 31:1625-9. [PMID: 26084772 DOI: 10.1007/s00381-015-2756-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 05/18/2015] [Indexed: 10/23/2022]
Abstract
Maple syrup urine disease (MSUD) is an inborn error of branched-chain amino acid metabolism, which usually presents in childhood with encephalopathy due to cerebral edema and dysmyelination. Even with treatment, metabolic stressors may precipitate later episodes of acute decompensation. Changes related to cerebral and white matter edema have been described by magnetic resonance imaging (MRI), and imaging can aid in both initial diagnosis and evaluation of decompensation. To date, there are no published known reports of cancer in patients with MSUD. Here, we present the first case report of an anaplastic astrocytoma in a teenager with MSUD, with a discussion of imaging findings and the use of magnetic resonance spectroscopy (MRS) to help distinguish between tumor and metabolic changes.
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Affiliation(s)
- Jessie Aw-Zoretic
- Department of Medical Imaging, Ann & Robert H. Lurie Children's Hospital, Chicago, IL, USA,
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Hou JW, Hwang TL. Different gene preferences of maple syrup urine disease in the aboriginal tribes of Taiwan. Pediatr Neonatol 2014; 55:213-7. [PMID: 24268812 DOI: 10.1016/j.pedneo.2013.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 08/27/2013] [Accepted: 09/23/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Maple syrup urine disease (MSUD) is a rare inborn error of metabolism caused by a deficiency of the branched-chain α-ketoacid dehydrogenase (BCKD) complex. Mutations in any one of the three different genes encoding for the BCKD components, namely, BCKDHA, BCKDHB, and DBT, may be responsible for this disease. In Taiwan, few MSUD cases were diagnosed clinically, and most of these patients are from Aboriginal tribes. MATERIALS AND METHODS To identify and detect the carrier frequency of MSUD in Taiwanese Aboriginal tribes, we performed biochemical and molecular studies from peripheral blood in MSUD patients and dried blood on filter paper in the enrolled screened populations. RESULTS Homozygous A208T and I281T of BCKDHA were found in two patients from Hans (non-Aboriginal Taiwanese), respectively; compound heterozygous mutations of the DBT gene [4.7 kb deletion/c.650-651insT (L217F or L217fsX223) and c.650-651insT/c.88-89delAT] were found in two patients from Amis, respectively, after direct DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism studies. There were no cases of deleted 4.7-kb heterozygote out of 302 normal people (Hans, n = 125; Atayal, n = 156; and Saisiyat, n = 21); by contrast, the DBT mutations c.650-651insT and deleted 4.7-kb heterozygote were noted in 2/121 and 1/121, respectively, from the general population of the Amis, a southeastern Taiwanese tribe. CONCLUSION Although the Taiwanese Austronesian Aboriginal tribes are considered to share a common origin, different gene preferences of MSUD were noted. The novel DBT mutation c.650-651insT was more prevalent than the deleted 4.7-kb heterozygote in the Amis population. The reported 4.7-kb deletion indicating a possible founder mutation may be preserved in the southern and eastern, but not in northern Aboriginal tribes of Taiwan.
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Affiliation(s)
- Jia-Woei Hou
- Department of Pediatrics, Cathay General Hospital, Taipei, Taiwan; Department of Pediatrics, Fu-Jen Catholic University School of Medicine, New Taipei City, Taiwan.
| | - Tsann-Long Hwang
- Department of Surgery, Chang Gung University School of Medicine, Taoyuan, Taiwan
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Jaafar N, Moleirinho A, Kerkeni E, Monastiri K, Seboui H, Amorim A, Prata MJ, Quental S. Molecular characterization of maple syrup urine disease patients from Tunisia. Gene 2013; 517:116-9. [PMID: 23313820 DOI: 10.1016/j.gene.2012.12.097] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Revised: 11/30/2012] [Accepted: 12/14/2012] [Indexed: 11/30/2022]
Abstract
Maple syrup urine disease (MSUD) is a rare disorder of branched-chain amino acids (BCAA) metabolism caused by the defective function of branched-chain α-ketoacid dehydrogenase complex (BCKD). The disease causal mutations can occur either in BCKDHA, BCKDHB or DBT genes encoding respectively the E1α, E1β and E2 subunits of the complex. In this study we report the molecular characterization of 3 Tunisian patients with the classic form of MSUD. Two novel putative mutations have been identified: the alteration c.716A>G (p.Glu239Gly) in BCKDHB and a small deletion (c.1333_1336delAATG; p.Asn445X) detected in DBT gene.
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Affiliation(s)
- N Jaafar
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Rua Dr. Roberto Frias s/n, 4200-465 Porto, Portugal
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Niu DM, Chien YH, Chiang CC, Ho HC, Hwu WL, Kao SM, Chiang SH, Kao CH, Liu TT, Chiang H, Hsiao KJ. Nationwide survey of extended newborn screening by tandem mass spectrometry in Taiwan. J Inherit Metab Dis 2010; 33:S295-305. [PMID: 20567911 DOI: 10.1007/s10545-010-9129-z] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 05/07/2010] [Accepted: 05/10/2010] [Indexed: 11/26/2022]
Abstract
In Taiwan, during the period March 2000 to June 2009, 1,495,132 neonates were screened for phenylketonuria (PKU) and homocystinuria (HCU), and 1,321,123 neonates were screened for maple syrup urine disease (MSUD), methylmalonic academia (MMA), medium-chain acyl-coenzyme A (CoA) dehydrogenase (MCAD) deficiency, isovaleric academia (IVA), and glutaric aciduria type 1 (GA-1) using tandem mass spectrometry (MS/MS). In a pilot study, 592,717 neonates were screened for citrullinemia, 3-methylcrotonyl-CoA carboxylase deficiency (3-MCC) and other fatty acid oxidation defects in the MS/MS newborn screening. A total of 170 newborns and four mothers were confirmed to have inborn errors of metabolism. The overall incidence was approximately 1/5,882 (1/6,219 without mothers). The most common inborn errors were defects of phenylalanine metabolism [five classic PKU, 20 mild PKU, 40 mild hyperphenylalaninemia (HPA), and 13 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency]. MSUD was the second most common amino acidopathy and, significantly, most MSUD patients (10/13) belonged to the Austronesian aboriginal tribes of southern Taiwan. The most frequently detected among organic acid disorders was 3-MCC deficiency (14 newborns and four mothers). GA-1 and MMA were the second most common organic acid disorders (13 and 13 newborns, respectively). In fatty acid disorders, five carnitine transport defect (CTD), five short-chain acyl-CoA dehydrogenase deficiency (SCAD), and two medium-chain acyl-CoA dehydrogenase (MCAD) deficiency were confirmed. This is the largest case of MS/MS newborn screening in an East-Asian population to date. We hereby report the incidences and outcomes of metabolic inborn error diseases found in our nationwide MS/MS newborn screening program.
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Affiliation(s)
- Dau-Ming Niu
- Institute of Clinical Medicine, School of Medicine, National Yang Ming University, No.155, Sec.2, Linong Street, Taipei, Taiwan.
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Brodtkorb E, Strand J, Backe PH, Lund AM, Bjørås M, Rootwelt T, Rootwelt H, Woldseth B, Eide L. Four novel mutations identified in Norwegian patients result in intermittent maple syrup urine disease when combined with the R301C mutation. Mol Genet Metab 2010; 100:324-32. [PMID: 20570198 DOI: 10.1016/j.ymgme.2010.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 04/26/2010] [Indexed: 01/03/2023]
Abstract
Maple syrup urine disease (MSUD) is caused by a defect in branched chain alpha-ketoacid dehydrogenase complex (BCKD), an essential metabolon for the catabolism of the branched chain amino acids. Here, we report four novel mutations in the DBT gene, encoding the transacylase subunit (E2) of BCKD, resulting in intermittent MSUD in seven Norwegian patients. The patients had episodes with neurological symptoms including lethargy and/or ataxia during childhood infections. All seven patients were heterozygous for the annotated R301C mutation. The second allelic mutations were identified in five patients; one nonsense mutation (G62X), two missense mutations (W84C and R376C) and a mutation in the 3' untranslated region (UTR; c. *358A>C) in two patients. These four novel mutations result in near depletion of E2 protein, and the common R301C protein contributes predominantly to the residual (14%) cellular BCKD activity. Structural analyses of the mutations implied that the W84C and R376C mutations affect stability of intramolecular domains in E2, while the R301C mutation likely disturbs E2 trimer assembly as previously reported. The UTR mutated allele coincided with a strong reduction in mRNA levels, as did the non-R301C specific allele in two patients where the second mutation could not be identified. In summary, the pathogenic effect of the novel mutations is depletion of cellular protein, and the intermittent form of MSUD appears to be attributed to the residual R301C mutant protein in these patients.
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Affiliation(s)
- Else Brodtkorb
- Institute of Clinical Biochemistry, Institute of Clinical Medicine, University of Oslo, Centre of Molecular Biology and Neuroscience, Sognsvannsveien 20, Oslo, Norway
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Skvorak KJ. Animal models of maple syrup urine disease. J Inherit Metab Dis 2009; 32:229-46. [PMID: 19263237 DOI: 10.1007/s10545-009-1086-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 12/15/2008] [Accepted: 12/18/2008] [Indexed: 01/03/2023]
Abstract
Maple syrup urine disease (MSUD) is an inherited aminoacidopathy resulting from dysfunction of the branched-chain keto acid dehydrogenase (BCKDH) complex. This disease is currently treated primarily by dietary restriction of branched-chain amino acids (BCAAs). However, dietary compliance is often challenging. Conversely, liver transplantation significantly improves outcomes, but donor organs are scarce and there are high costs and potential risks associated with this invasive procedure. Therefore, improved treatment options for MSUD are needed. Development of novel treatments could be facilitated by animal models that accurately mimic the human disease. Animal models provide a useful system in which to explore disease mechanisms and new preclinical therapies. Here we review MSUD and currently available animal models and their corresponding relevance to the human disorder. Using animal models to gain a more complete understanding of the pathophysiology behind the human disease may lead to new or improved therapies to treat or potentially cure the disorder.
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Affiliation(s)
- K J Skvorak
- Graduate Program in the Department of Molecular Genetics and Biochemistry, University of Pittsburgh, Pittsburgh, PA, USA.
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Quental S, Martins E, Vilarinho L, Amorim A, João Prata M. Maple syrup urine disease due to a new large deletion at BCKDHA caused by non-homologous recombination. J Inherit Metab Dis 2008; 31 Suppl 2:S457-60. [PMID: 19085071 DOI: 10.1007/s10545-008-1046-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 10/22/2008] [Accepted: 10/24/2008] [Indexed: 11/24/2022]
Abstract
Maple syrup urine disease (MSUD) is a rare disorder of branched-chain amino acid (BCAA) metabolism caused by the defective function of branched-chain α-ketoacid dehydrogenase complex (BCKD). Many MSUD-causing mutations have already been described in genes that encode the complex (BCKDHA, BCKDHB and DBT), but up to now only four large deletions are known, all located in the DBT gene. In a previous study we identified a Portuguese MSUD patient with a homozygous deletion of exons 2, 3 and 4 at the BCKDHA gene; however, the corresponding breakpoints and, consequently, the exact deletion extension were not identified. Here, using long-range PCR and sequencing methodologies we were able to refine the characterization of this gross rearrangement. A genomic DNA loss of about 13.8 kb was detected, starting at intron 1 and ending at intron 4, thus encompassing exons 2, 3 and 4. Molecular characterization showed that the deletion junction contained a short sequence whose motif was CGGG. Since this motif is present in introns 1 and 4 of normal genomic DNA, we have hypothesized that non-homologous recombination was the mechanism underlying the identified large deletion, within which the CGGG could be derived either from intron 1 or from intron 4.
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Affiliation(s)
- S Quental
- IPATIMUP - Institute of Pathology and Molecular Immunology of University of Porto, Rua Dr Roberto Frias s/n, 4200-465, Porto, Portugal.
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Silao CLT, Padilla CD, Matsuo M. Early diagnosis of maple syrup urine disease using polymerase chain reaction-based mutation detection. Pediatr Int 2008; 50:312-4. [PMID: 18533943 DOI: 10.1111/j.1442-200x.2008.02610.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Maple syrup urine disease (MSUD) is an autosomal recessive disorder caused by defective activity of the branched-chain alpha-ketoacid dehydrogenase enzyme complex. Early diagnosis and management of MSUD are imperative for preventing permanent neurological impairments. In the Philippines, a 4.7 kb deletion in the dihydrolipoamide branched-chain transacylase E2 (DBT) gene has been commonly identified in MSUD patients. Polymerase chain reaction (PCR) amplification of a junction fragment between intron 10 and exon 11 has been used to detect this deletion. The purpose of the present paper was to use PCR-based mutation detection of the deletion mutation to diagnose MSUD in neonates in order to provide proper diagnosis and effective treatment. METHODS A region encompassing exon 11 and the junction fragment of the E2 (DBT) gene was PCR amplified from genomic DNA prepared from two neonates at risk for MSUD. RESULTS PCR amplification of both exon 11 and the junction fragment from one of the neonates demonstrated that this case was a heterozygous carrier of the deletion. Thus, normal feeding was started. For the other neonate, PCR amplification of the junction fragment was successful, whereas the region encompassing exon 11 was not amplified. This neonate was genotyped as homozygous for the deletion, and treatment for MSUD was provided immediately. CONCLUSION Examination of the deletion mutation in the E2 (DBT) gene facilitated early MSUD diagnosis and was beneficial for the determination of the proper course of treatment.
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Affiliation(s)
- Catherine Lynn T Silao
- Institute of Human Genetics, National Institutes of Health Philippines, Manila, Philippines
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