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van Vliet K, Dijkstra AM, Bouva MJ, van der Krogt J, Bijsterveld K, van der Sluijs F, de Sain-van der Velden MG, Koop K, Rossi A, Thomas JA, Patera CA, Kiewiet MBG, Waters PJ, Cyr D, Boelen A, van Spronsen FJ, Heiner-Fokkema MR. Maleic acid is a biomarker for maleylacetoacetate isomerase deficiency; implications for newborn screening of tyrosinemia type 1. J Inherit Metab Dis 2023; 46:1104-1113. [PMID: 37545091 DOI: 10.1002/jimd.12669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 07/28/2023] [Accepted: 08/03/2023] [Indexed: 08/08/2023]
Abstract
Dried blood spot succinylacetone (SA) is often used as a biomarker for newborn screening (NBS) for tyrosinemia type 1 (TT1). However, false-positive SA results are often observed. Elevated SA may also be due to maleylacetoacetate isomerase deficiency (MAAI-D), which appears to be clinically insignificant. This study investigated whether urine organic acid (uOA) and quantitative urine maleic acid (Q-uMA) analyses can distinguish between TT1 and MAAI-D. We reevaluated/measured uOA (GC-MS) and/or Q-uMA (LC-MS/MS) in available urine samples of nine referred newborns (2 TT1, 7 false-positive), eight genetically confirmed MAAI-D children, and 66 controls. Maleic acid was elevated in uOA of 5/7 false-positive newborns and in the three available samples of confirmed MAAI-D children, but not in TT1 patients. Q-uMA ranged from not detectable to 1.16 mmol/mol creatinine in controls (n = 66) and from 0.95 to 192.06 mmol/mol creatinine in false-positive newborns and MAAI-D children (n = 10). MAAI-D was genetically confirmed in 4/7 false-positive newborns, all with elevated Q-uMA, and rejected in the two newborns with normal Q-uMA. No sample was available for genetic analysis of the last false-positive infant with elevated Q-uMA. Our study shows that MAAI-D is a recognizable cause of false-positive TT1 NBS results. Elevated urine maleic acid excretion seems highly effective in discriminating MAAI-D from TT1.
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Affiliation(s)
- K van Vliet
- Section of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - A M Dijkstra
- Section of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - M J Bouva
- Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - J van der Krogt
- Laboratory of Metabolic diseases, Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - K Bijsterveld
- Laboratory of Metabolic diseases, Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - F van der Sluijs
- Laboratory of Metabolic diseases, Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - M G de Sain-van der Velden
- Section Metabolic Diagnostics, Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - K Koop
- Department of Pediatrics, section Metabolic Diseases, Wilhelmina Children's Hospital, Utrecht, The Netherlands
| | - A Rossi
- Department of Translational Medicine, Section of Pediatrics, University of Naples "Federico II", Italy
| | - J A Thomas
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - C A Patera
- Department of Genetics and Metabolism, Shodair Children's Hospital, Helena, Montana, USA
| | - M B G Kiewiet
- Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - P J Waters
- Medical Genetics Service, Department of Laboratory Medicine, CHU Sherbrooke and Department of Pediatrics, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - D Cyr
- Medical Genetics Service, Department of Laboratory Medicine, CHU Sherbrooke and Department of Pediatrics, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - A Boelen
- Endocrine Laboratory, Department of Laboratory Medicine, Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - F J van Spronsen
- Section of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - M R Heiner-Fokkema
- Laboratory of Metabolic diseases, Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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Thuriot F, Gravel E, Buote C, Doyon M, Lapointe E, Marcoux L, Larue S, Nadeau A, Chénier S, Waters PJ, Jacques PÉ, Gravel S, Lévesque S. Molecular diagnosis of muscular diseases in outpatient clinics: A Canadian perspective. Neurol Genet 2020; 6:e408. [PMID: 32337335 PMCID: PMC7164974 DOI: 10.1212/nxg.0000000000000408] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 01/24/2020] [Indexed: 12/18/2022]
Abstract
Objective To evaluate the diagnostic yield of an 89-gene panel in a large cohort of patients with suspected muscle disorders and to compare the diagnostic yield of gene panel and exome sequencing approaches. Methods We tested 1,236 patients from outpatient clinics across Canada using a gene panel and performed exome sequencing for 46 other patients with sequential analysis of 89 genes followed by all mendelian genes. Sequencing and analysis were performed in patients with muscle weakness or symptoms suggestive of a muscle disorder and showing at least 1 supporting clinical laboratory. Results We identified a molecular diagnosis in 187 (15.1%) of the 1,236 patients tested with the 89-gene panel. Diagnoses were distributed across 40 different genes, but 6 (DMD, RYR1, CAPN3, PYGM, DYSF, and FKRP) explained about half of all cases. Cardiac anomalies, positive family history, age <60 years, and creatine kinase >1,000 IU/L were all associated with increased diagnostic yield. Exome sequencing identified a diagnosis in 10 (21.7%) of the 46 patients tested. Among these, 3 were attributed to genes not included in the 89-gene panel. Despite differences in median coverage, only 1 of the 187 diagnoses that were identified on gene panel in the 1,236 patients could have been potentially missed if exome sequencing had been performed instead. Conclusions Our study supports the use of gene panel testing in patients with suspected muscle disorders from outpatient clinics. It also shows that exome sequencing has a low risk of missing diagnoses compared with gene panel, while potentially increasing the diagnostic yield of patients with muscle disorders.
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Affiliation(s)
- Fanny Thuriot
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Elaine Gravel
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Caroline Buote
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Marianne Doyon
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Elvy Lapointe
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Lydia Marcoux
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Sandrine Larue
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Amélie Nadeau
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Sébastien Chénier
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Paula J Waters
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Pierre-Étienne Jacques
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Serge Gravel
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
| | - Sébastien Lévesque
- Department of Pediatrics (F.T., E.G., C.B., M.D., L.M., A.N., S.C., P.J.W., S.G., S. Lévesque), Université de Sherbrooke; Sherbrooke Genomic Medicine (F.T., E.G., C.B., S.G., S. Lévesque); RNomic's Platform (E.L.), Université de Sherbrooke; Department of Neurology (S. Larue), Notre-Dame Hospital, Université de Montréal; Department of Biology (P.-É.J.), Université de Sherbrooke; and Department of Computer Sciences (P.-É.J.), Université de Sherbrooke, Quebec, Canada
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Agudelo D, Carter S, Velimirovic M, Duringer A, Rivest JF, Levesque S, Loehr J, Mouchiroud M, Cyr D, Waters PJ, Laplante M, Moineau S, Goulet A, Doyon Y. Versatile and robust genome editing with Streptococcus thermophilus CRISPR1-Cas9. Genome Res 2020; 30:107-117. [PMID: 31900288 PMCID: PMC6961573 DOI: 10.1101/gr.255414.119] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 12/17/2019] [Indexed: 12/18/2022]
Abstract
Targeting definite genomic locations using CRISPR-Cas systems requires a set of enzymes with unique protospacer adjacent motif (PAM) compatibilities. To expand this repertoire, we engineered nucleases, cytosine base editors, and adenine base editors from the archetypal Streptococcus thermophilus CRISPR1-Cas9 (St1Cas9) system. We found that St1Cas9 strain variants enable targeting to five distinct A-rich PAMs and provide a structural basis for their specificities. The small size of this ortholog enables expression of the holoenzyme from a single adeno-associated viral vector for in vivo editing applications. Delivery of St1Cas9 to the neonatal liver efficiently rewired metabolic pathways, leading to phenotypic rescue in a mouse model of hereditary tyrosinemia. These robust enzymes expand and complement current editing platforms available for tailoring mammalian genomes.
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Affiliation(s)
- Daniel Agudelo
- Centre Hospitalier Universitaire de Québec Research Center-Université Laval, Québec, Québec G1V 4G2, Canada
| | - Sophie Carter
- Centre Hospitalier Universitaire de Québec Research Center-Université Laval, Québec, Québec G1V 4G2, Canada
| | - Minja Velimirovic
- Centre Hospitalier Universitaire de Québec Research Center-Université Laval, Québec, Québec G1V 4G2, Canada
| | - Alexis Duringer
- Centre Hospitalier Universitaire de Québec Research Center-Université Laval, Québec, Québec G1V 4G2, Canada
| | - Jean-François Rivest
- Centre Hospitalier Universitaire de Québec Research Center-Université Laval, Québec, Québec G1V 4G2, Canada
| | - Sébastien Levesque
- Centre Hospitalier Universitaire de Québec Research Center-Université Laval, Québec, Québec G1V 4G2, Canada
| | - Jeremy Loehr
- Centre Hospitalier Universitaire de Québec Research Center-Université Laval, Québec, Québec G1V 4G2, Canada
| | - Mathilde Mouchiroud
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ)-Université Laval, Québec, Québec G1V 4G5, Canada
| | - Denis Cyr
- Service de Génétique médicale, Département de Pédiatrie, Centre Hospitalier Universitaire de Sherbrooke (CHUS), et CRCHUS, Sherbrooke, Québec J1H 5N4, Canada
| | - Paula J Waters
- Service de Génétique médicale, Département de Pédiatrie, Centre Hospitalier Universitaire de Sherbrooke (CHUS), et CRCHUS, Sherbrooke, Québec J1H 5N4, Canada
| | - Mathieu Laplante
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ)-Université Laval, Québec, Québec G1V 4G5, Canada.,Université Laval Cancer Research Centre, Québec, Québec G1V 0A6, Canada
| | - Sylvain Moineau
- Département de biochimie, de microbiologie, et de bio-informatique, Faculté des sciences et de génie, Université Laval, Québec, Québec G1V 0A6, Canada.,Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec, Québec G1V 0A6, Canada.,Félix d'Hérelle Reference Center for Bacterial Viruses, Faculté de médecine dentaire, Université Laval, Québec, Québec G1V 0A6, Canada
| | - Adeline Goulet
- Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique (CNRS), Campus de Luminy, 13288 Marseille Cedex 09, France.,Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, Campus de Luminy, 13288 Marseille Cedex 09, France
| | - Yannick Doyon
- Centre Hospitalier Universitaire de Québec Research Center-Université Laval, Québec, Québec G1V 4G2, Canada.,Université Laval Cancer Research Centre, Québec, Québec G1V 0A6, Canada
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Waters PJ, Lace B, Buhas D, Gravel S, Cyr D, Boucher RM, Bernard G, Lévesque S, Maranda B. HSD10 mitochondrial disease: p.Leu122Val variant, mild clinical phenotype, and founder effect in French-Canadian patients from Quebec. Mol Genet Genomic Med 2019; 7:e1000. [PMID: 31654490 PMCID: PMC6900358 DOI: 10.1002/mgg3.1000] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/28/2019] [Accepted: 09/03/2019] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND HSD10 mitochondrial disease (HSD10MD), originally described as a deficiency of 2-methyl-3-hydroxybutyryl-CoA dehydrogenase (MHBD), is a rare X-linked disorder of a moonlighting protein encoded by the HSD17B10. The diagnosis is usually first suspected on finding elevated isoleucine degradation metabolites in urine, reflecting decreased MHBD activity. However, it is now known that clinical disease pathogenesis reflects other independent functions of the HSD10 protein; particularly its essential role in mitochondrial transcript processing and tRNA maturation. The classical phenotype of HSD10MD in affected males is an infantile-onset progressive neurodegenerative disorder associated with severe mitochondrial dysfunction. PATIENTS, METHODS, AND RESULTS In four unrelated families, we identified index patients with MHBD deficiency, which implied a diagnosis of HSD10MD. Each index patient was independently investigated because of neurological or developmental concerns. All had persistent elevations of urinary 2-methyl-3-hydroxybutyric acid and tiglylglycine. Analysis of HSD17B10 identified a single missense variant, c.364C>G, p.Leu122Val, in each case. This rare variant (1/183336 alleles in gnomAD) was previously reported in one Dutch patient and was described as pathogenic. The geographic origins of our families and results of haplotype analysis together provide evidence of a founder effect for this variant in Quebec. Notably, we identified an asymptomatic hemizygous adult male in one family, while a second independent genetic disorder contributed substantially to the clinical phenotypes observed in probands from two other families. CONCLUSION The phenotype associated with p.Leu122Val in HSD17B10 currently appears to be attenuated and nonprogressive. This report widens the spectrum of phenotypic severity of HSD10MD and contributes to genotype-phenotype correlation. At present, we consider p.Leu122Val a "variant of uncertain significance." Nonetheless, careful follow-up of our patients remains advisable, to assess long-term clinical course and ensure appropriate management. It will also be important to identify other potential patients in our population and to characterize their phenotype.
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Affiliation(s)
- Paula J Waters
- Medical Genetics, Department of Pediatrics, Université de Sherbrooke-CHUS, Sherbrooke, QC, Canada.,CRCHUS, Sherbrooke, QC, Canada
| | - Baiba Lace
- Medical Genetics, Department of Pediatrics, CHU de Québec-Université Laval, Quebec, Canada
| | - Daniela Buhas
- Medical Genetics, Department of Specialized Medicine, MUHC, Montreal, Canada.,Department of Human Genetics, McGill University, Montreal, Canada
| | - Serge Gravel
- Medical Genetics, Department of Pediatrics, Université de Sherbrooke-CHUS, Sherbrooke, QC, Canada.,CRCHUS, Sherbrooke, QC, Canada
| | - Denis Cyr
- Medical Genetics, Department of Pediatrics, Université de Sherbrooke-CHUS, Sherbrooke, QC, Canada.,CRCHUS, Sherbrooke, QC, Canada
| | - Renée-Myriam Boucher
- Neurology, Department of Pediatrics, CHU de Québec-Université Laval, Quebec, QC, Canada
| | - Geneviève Bernard
- Medical Genetics, Department of Specialized Medicine, MUHC, Montreal, Canada.,Department of Human Genetics, McGill University, Montreal, Canada.,Departments of Neurology/Neurosurgery and Pediatrics, McGill University, Montreal, Canada.,RI-MUHC, Montreal, Canada
| | - Sébastien Lévesque
- Medical Genetics, Department of Pediatrics, Université de Sherbrooke-CHUS, Sherbrooke, QC, Canada.,CRCHUS, Sherbrooke, QC, Canada
| | - Bruno Maranda
- Medical Genetics, Department of Pediatrics, Université de Sherbrooke-CHUS, Sherbrooke, QC, Canada.,CRCHUS, Sherbrooke, QC, Canada
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5
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Levtova A, Waters PJ, Buhas D, Lévesque S, Auray-Blais C, Clarke JTR, Laframboise R, Maranda B, Mitchell GA, Brunel-Guitton C, Braverman NE. Combined malonic and methylmalonic aciduria due to ACSF3 mutations: Benign clinical course in an unselected cohort. J Inherit Metab Dis 2019; 42:107-116. [PMID: 30740739 DOI: 10.1002/jimd.12032] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND The clinical significance of combined malonic and methylmalonic aciduria due to ACSF3 deficiency (CMAMMA) is controversial. In most publications, affected patients were identified during the investigation of various complaints. METHODS Using a cross-sectional multicenter retrospective natural history study, we describe the course of all known CMAMMA individuals in the province of Quebec. RESULTS We identified 25 CMAMMA patients (6 months to 30 years old) with a favorable outcome regardless of treatment. All but one came to clinical attention through the Provincial Neonatal Urine Screening Program (screening on day 21 of life). Median methylmalonic acid (MMA) levels ranged from 107 to 857 mmol/mol creatinine in urine (<10) and from 8 to 42 μmol/L in plasma (<0.4); median urine malonic acid (MA) levels ranged from 9 to 280 mmol/mol creatinine (<5). MMA was consistently higher than MA. These findings are comparable to those previously reported in CMAMMA. Causal ACSF3 mutations were identified in all patients for whom genotyping was performed (76% of cases). The most common ACSF3 mutations in our cohort were c.1075G > A (p.E359K) and c.1672C > T (p.R558W), representing 38.2 and 20.6% of alleles in genotyped families, respectively; we also report several novel mutations. CONCLUSION Because our province still performs urine newborn screening, our patient cohort is the only one free of selection bias. Therefore, the favorable clinical course observed suggests that CMAMMA is probably a benign condition, although we cannot exclude the possibility that a small minority of patients may present symptoms attributable to CMAMMA, perhaps as a result of interactions with other genetic or environmental factors.
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Affiliation(s)
- Alina Levtova
- Division of Medical Genetics, Department of Medicine, Centre Hospitalier de l'Université de Montréal (CHUM) and Université de Montréal, Tour Viger, 900 rue St-Denis, R07-462, Montreal, Quebec H2X 0A9, Canada
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, 3175 Côte-Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - Paula J Waters
- Division of Medical Genetics, Department of Pediatrics, Université de Sherbrooke, CHUS, 3001 12th Avenue North, Sherbrooke, Quebec J1H 5N4, Canada
| | - Daniela Buhas
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
- Departments of Medical Genetics and Pediatrics, Montreal Children's Hospital, Montreal, Quebec, Canada
| | - Sébastien Lévesque
- Division of Medical Genetics, Department of Pediatrics, Université de Sherbrooke, CHUS, 3001 12th Avenue North, Sherbrooke, Quebec J1H 5N4, Canada
| | - Christiane Auray-Blais
- Division of Medical Genetics, Department of Pediatrics, Université de Sherbrooke, CHUS, 3001 12th Avenue North, Sherbrooke, Quebec J1H 5N4, Canada
| | - Joe T R Clarke
- Division of Medical Genetics, Department of Pediatrics, Université de Sherbrooke, CHUS, 3001 12th Avenue North, Sherbrooke, Quebec J1H 5N4, Canada
| | - Rachel Laframboise
- Department of Pediatrics, Laval University Hospital Centre, Quebec, Quebec, Canada
| | - Bruno Maranda
- Division of Medical Genetics, Department of Pediatrics, Université de Sherbrooke, CHUS, 3001 12th Avenue North, Sherbrooke, Quebec J1H 5N4, Canada
- Department of Pediatrics, Laval University Hospital Centre, Quebec, Quebec, Canada
| | - Grant A Mitchell
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, 3175 Côte-Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - Catherine Brunel-Guitton
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, 3175 Côte-Sainte-Catherine, Montreal, Quebec H3T 1C5, Canada
| | - Nancy E Braverman
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
- Departments of Medical Genetics and Pediatrics, Montreal Children's Hospital, Montreal, Quebec, Canada
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Kitzler TM, Gupta IR, Osterman B, Poulin C, Trakadis Y, Waters PJ, Buhas DC. Acute and Chronic Management in an Atypical Case of Ethylmalonic Encephalopathy. JIMD Rep 2018; 45:57-63. [PMID: 30349987 DOI: 10.1007/8904_2018_136] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 08/01/2018] [Accepted: 08/17/2018] [Indexed: 12/19/2022] Open
Abstract
Ethylmalonic encephalopathy (EE) is caused by mutations in the ETHE1 gene. ETHE1 is vital for the catabolism of hydrogen sulfide (H2S). Patients with pathogenic mutations in ETHE1 have markedly increased thiosulfate, which is a reliable index of H2S levels. Accumulation of H2S is thought to cause the characteristic metabolic derangement found in EE. Recently introduced treatment strategies in EE, such as combined use of metronidazole (MNZ) and N-acetylcysteine (NAC), are aimed at lowering chronic H2S load. Experience with treatment strategies directed against acute episodes of metabolic decompensation (e.g., hemodialysis) is limited. Here we present an unusually mild, molecularly confirmed, case of EE in a 19-year-old male on chronic treatment with MNZ and NAC. During an acute episode of metabolic decompensation, we employed continuous renal replacement therapy (CRRT) to regain metabolic control. On continuous treatment with NAC and MNZ during the months preceding the acute event, plasma thiosulfate levels ranged from 1.6 to 4 μg/mL (reference range up to 2 μg/mL) and had a mean value of 2.5 μg/mL. During the acute decompensation, thiosulfate levels were 6.7 μg/mL, with hyperlactatemia and perturbed organic acid, acylglycine, and acylcarnitine profiles. CRRT decreased thiosulfate within 24 h to 1.4 μg/mL. Following discontinuation of CRRT, mean thiosulfate levels were 3.2 μg/mL (range, 2.4-3.7 μg/mL) accompanied by clinical improvement with metabolic stabilization of blood gas, acylcarnitine, organic acid, and acylglycine profiles. In conclusion, CRRT may help to regain metabolic control in patients with EE who have an acute metabolic decompensation on chronic treatment with NAC and MNZ.
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Affiliation(s)
- Thomas M Kitzler
- Department of Medical Genetics, McGill University Health Centre, Montreal, QC, Canada.
| | - Indra R Gupta
- Department of Pediatrics, Division of Nephrology, McGill University Health Centre, Montreal, QC, Canada
| | - Bradley Osterman
- Department of Pediatric Neurology, Centre Hospitalier de l'Université Laval (CHUL), Quebec City, QC, Canada
| | - Chantal Poulin
- Department of Pediatrics, Division of Neurology, McGill University Health Centre, Montreal, QC, Canada
| | - Yannis Trakadis
- Department of Medical Genetics, McGill University Health Centre, Montreal, QC, Canada
| | - Paula J Waters
- Medical Genetics Service, Department of Pediatrics, University of Sherbrooke Hospital Centre (CHUS), Sherbrooke, QC, Canada
| | - Daniela C Buhas
- Department of Medical Genetics, McGill University Health Centre, Montreal, QC, Canada
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Yang H, Rossignol F, Cyr D, Laframboise R, Wang SP, Soucy JF, Berthier MT, Giguère Y, Waters PJ, Mitchell GA. Mildly elevated succinylacetone and normal liver function in compound heterozygotes with pathogenic and pseudodeficient FAH alleles. Mol Genet Metab Rep 2017; 14:55-58. [PMID: 29326876 PMCID: PMC5758842 DOI: 10.1016/j.ymgmr.2017.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 12/13/2017] [Indexed: 12/27/2022] Open
Abstract
Background A high level of succinylacetone (SA) in blood is a sensitive, specific marker for the screening and diagnosis of hepatorenal tyrosinemia (HT1, MIM 276700). HT1 is caused by mutations in the FAH gene, resulting in deficiency of fumarylacetoacetate hydrolase. HT1 newborns are usually clinically asymptomatic, but have coagulation abnormalities revealing liver dysfunction. Treatment with nitisinone (NTBC) plus dietary restriction of tyrosine and phenylalanine prevents the complications of HT1 Observations Two newborns screened positive for SA but had normal coagulation testing. Plasma and urine SA levels were 3–5 fold above the reference range but were markedly lower than in typical HT1. Neither individual received nitisinone or dietary therapy. They remain clinically normal, currently aged 9 and 15 years. Each was a compound heterozygote, having a splicing variant in trans with a prevalent “pseudodeficient” FAH allele, c.1021C > T (p.Arg341Trp), which confers partial FAH activity. All newborns identified with mild hypersuccinylacetonemia in Québec have had genetic deficiencies of tyrosine degradation: either deficiency of the enzyme preceding FAH, maleylacetoacetate isomerase, or partial deficiency of FAH itself. Conclusion Compound heterozygotes for c.1021C > T (p.Arg341Trp) and a severely deficient FAH allele have mild hypersuccinylacetonemia and to date they have remained asymptomatic without treatment. It is important to determine the long term outcome of such individuals.
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Affiliation(s)
- Hao Yang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine, Université de Montréal, Montréal, Québec, Canada
| | - Francis Rossignol
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine, Université de Montréal, Montréal, Québec, Canada
| | - Denis Cyr
- Service de Génétique médicale, Département de Pédiatrie, Centre hospitalier universitaire de Sherbrooke (CHUS), Sherbrooke, Québec, Canada
| | - Rachel Laframboise
- Service de Génétique médicale, Département de Pédiatrie, CHU de Québec-Centre hospitalier de l'Université Laval (CHUL), Québec, Canada
| | - Shu Pei Wang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine, Université de Montréal, Montréal, Québec, Canada
| | - Jean-François Soucy
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine, Université de Montréal, Montréal, Québec, Canada
| | - Marie-Thérèse Berthier
- Programme québécois de Dépistage Néonatal Sanguin, CHU de Québec-Université Laval, Québec, Canada
| | - Yves Giguère
- Programme québécois de Dépistage Néonatal Sanguin, CHU de Québec-Université Laval, Québec, Canada
| | - Paula J. Waters
- Service de Génétique médicale, Département de Pédiatrie, Centre hospitalier universitaire de Sherbrooke (CHUS), Sherbrooke, Québec, Canada
- Corresponding authors.
| | - Grant A. Mitchell
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine, Université de Montréal, Montréal, Québec, Canada
- Corresponding authors.
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Battat R, Kopylov U, Byer J, Sewitch MJ, Rahme E, Nedjar H, Zelikovic E, Dionne S, Bessissow T, Afif W, Waters PJ, Seidman E, Bitton A. Vitamin B12 deficiency in inflammatory bowel disease: a prospective observational pilot study. Eur J Gastroenterol Hepatol 2017; 29:1361-1367. [PMID: 28953003 DOI: 10.1097/meg.0000000000000970] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND AIM Diagnostic and management guidelines for vitamin B12 (cobalamin, Cbl) deficiency in inflammatory bowel disease (IBD) are lacking. True deficiency is defined as Cbl concentrations below reference range combined with elevated methylmalonic acid (MMA) concentrations. Studies analyzing Cbl status in IBD use only Cbl concentrations without confirmatory MMA. This study aims to determine the proportion of IBD patients with Cbl concentrations below reference range and their predisposing clinical and genetic characteristics. We then compared this to the proportion with true deficiency. PATIENTS AND METHODS In a prospective observational pilot study of adult IBD outpatients, Cbl concentrations, MMA levels, and fucosyltransferase 2 mutations were measured at clinic visits. RESULTS A total of 66 Crohn's disease (CD) and 30 ulcerative colitis (UC) patients were recruited. Mean Cbl concentrations (pmol/l) in CD (253.7) were not significantly lower than UC (320.5, P=0.24). Serum Cbl below reference range (<148) was observed in 7.6 and 10% of CD and UC patients, respectively (P=0.70). True deficiency in CD and UC was 3 and 3.3%, respectively (P=1.0). Patients with ileal resections more than 30 cm had lower mean Cbl concentrations (177, P=0.02) and a trend toward higher proportions with Cbl levels below reference range (40%, P=0.06), but not increased deficiency rates (0%, P=1.0). Disease location, severity, and fucosyltransferase 2 mutations were not associated with altered Cbl status. CONCLUSION True Cbl deficiency was rare in IBD patients in this study. A disparity in Cbl status exists when confirmatory MMA levels are used compared with Cbl concentrations alone. Asymptomatic IBD patients with low serum Cbl require confirmatory tests to guide management and avoid unnecessary treatment.
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Affiliation(s)
- Robert Battat
- aDivision of Gastroenterology, Department of Medicine, McGill University Health Centre bDivision of Clinical Epidemiology, Department of Medicine, Research Institute of the McGill University Health Centre cDepartment of Medicine, McGill University dDivision of Gastroenterology, Department of Medicine, Jewish General Hospital, Montreal eMedical Genetics Service, Department of Medicine, Centre Hospitalier Universitaire de Sherbrooke (CHUS), University of Sherbrooke, Sherbrooke fDepartment of Gastroenterology, Sheba Medical Center Tel Hashomer and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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Waters PJ, Thuriot F, Clarke JT, Gravel S, Watkins D, Rosenblatt DS, Lévesque S. Methylmalonyl-coA epimerase deficiency: A new case, with an acute metabolic presentation and an intronic splicing mutation in the MCEE gene. Mol Genet Metab Rep 2016; 9:19-24. [PMID: 27699154 PMCID: PMC5037260 DOI: 10.1016/j.ymgmr.2016.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/02/2016] [Accepted: 09/03/2016] [Indexed: 11/27/2022] Open
Abstract
Methylmalonyl-coA epimerase (MCE) follows propionyl-coA carboxylase and precedes methylmalonyl-coA mutase in the pathway converting propionyl-coA to succinyl-coA. MCE deficiency has previously been described in six patients, one presenting with metabolic acidosis, the others with nonspecific neurological symptoms or asymptomatic. The clinical significance and biochemical characteristics of this rare condition have been incompletely defined. We now describe a patient who presented acutely at 5 years of age with vomiting, dehydration, confusion, severe metabolic acidosis and mild hyperammonemia. At presentation, organic acid profiles were dominated by increased ketones and 3-hydroxypropionate, with moderately elevated methylcitrate and propionylglycine, and acylcarnitine profiles showed marked C3 (propionylcarnitine) elevation with normal C4DC (methylmalonylcarnitine + succinylcarnitine). Propionic acidemia was initially suspected, but it was subsequently noted that methylmalonic acid was mildly but persistently elevated in urine, and clearly elevated in plasma and cerebrospinal fluid. The overall biochemical profile prompted consideration of MCE deficiency. Studies on cultured fibroblasts showed moderately decreased propionate incorporation. Complementation analysis permitted assignment to the MCEE group. A heterozygous p.Arg47Ter (p.R47*) mutation in the MCEE gene was identified by sequencing of exons, and RNA studies identified a novel intronic splicing mutation, c.379-644A > G, confirming the diagnosis of MCE deficiency. Following the initial severe presentation, development has been normal and the clinical course over the subsequent six years has remained relatively uneventful on an essentially normal diet. This report contributes to the clinical and biochemical characterisation of this rare disorder, while highlighting potential causes of under-diagnosis or of diagnostic confusion.
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Affiliation(s)
- Paula J. Waters
- Medical Genetics Service, Department of Pediatrics, Centre hospitalier universitaire de Sherbrooke (CHUS) and University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Fanny Thuriot
- Medical Genetics Service, Department of Pediatrics, Centre hospitalier universitaire de Sherbrooke (CHUS) and University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Joe T.R. Clarke
- Medical Genetics Service, Department of Pediatrics, Centre hospitalier universitaire de Sherbrooke (CHUS) and University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Serge Gravel
- Medical Genetics Service, Department of Pediatrics, Centre hospitalier universitaire de Sherbrooke (CHUS) and University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - David Watkins
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | | | - Sébastien Lévesque
- Medical Genetics Service, Department of Pediatrics, Centre hospitalier universitaire de Sherbrooke (CHUS) and University of Sherbrooke, Sherbrooke, Quebec, Canada
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Yang H, Al-Hertani W, Cyr D, Laframboise R, Parizeault G, Wang SP, Rossignol F, Berthier MT, Giguère Y, Waters PJ, Mitchell GA. Hypersuccinylacetonaemia and normal liver function in maleylacetoacetate isomerase deficiency. J Med Genet 2016; 54:241-247. [PMID: 27876694 DOI: 10.1136/jmedgenet-2016-104289] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/29/2016] [Accepted: 11/01/2016] [Indexed: 11/04/2022]
Abstract
BACKGROUND A high level of succinylacetone (SA) in blood is a sensitive, specific newborn screening marker for hepatorenal tyrosinemia type 1 (HT1, MIM 276700) caused by deficiency of fumarylacetoacetate hydrolase (FAH). Newborns with HT1 are usually clinically asymptomatic but show liver dysfunction with coagulation abnormalities (prolonged prothrombin time and/or high international normalised ratio). Early treatment with nitisinone (NTBC) plus dietary restriction of tyrosine and phenylalanine prevents the complications of severe liver disease and neurological crises. METHODS AND RESULTS Six newborns referred for hypersuccinylacetonaemia but who had normal coagulation testing on initial evaluation had sequence variants in the GSTZ1 gene, encoding maleylacetoacetate isomerase (MAAI), the enzyme preceding FAH in tyrosine degradation. Initial plasma SA levels ranged from 233 to 1282 nmol/L, greater than normal (<24 nmol/L) but less than the initial values of patients with HT1 (16 944-74 377 nmol/L, n=15). Four individuals were homozygous for c.449C>T (p.Ala150Val). One was compound heterozygous for c.259C>T (p.Arg87Ter) and an intronic sequence variant. In one, a single heterozygous GSTZ1 sequence variant was identified, c.295G>A (p.Val99Met). Bacterial expression of p.Ala150Val and p.Val99Met revealed low MAAI activity. The six individuals with mild hypersuccinylacetonaemia (MHSA) were not treated with diet or nitisinone. Their clinical course has been normal for up to 13 years. CONCLUSIONS MHSA can be caused by sequence variants in GSTZ1. Such individuals have thus far remained asymptomatic despite receiving no specific treatment.
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Affiliation(s)
- Hao Yang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada.,College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Walla Al-Hertani
- Departments of Medical Genetics and Paediatrics, Cumming School of Medicine, University of Calgary and Alberta Children's Hospital, Calgary, Alberta, Canada.,Department of Medical Genetics, Centre universitaire de Santé McGill (CUSM), Québec, Canada
| | - Denis Cyr
- Service de Génétique médicale, Département de Pédiatrie, Centre hospitalier universitaire de Sherbrooke (CHUS), Sherbrooke, Québec, Canada
| | - Rachel Laframboise
- Service de Génétique médicale, Département de Pédiatrie, CHU de Québec-Centre hospitalier de l'Université Laval (CHUL), Québec City, Québec, Canada
| | - Guy Parizeault
- Département de Pédiatrie, Centre Hospitalier de la Sagamie, Sagamie, Québec, Canada
| | - Shu Pei Wang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada
| | - Francis Rossignol
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada
| | - Marie-Thérèse Berthier
- Programme québécois de Dépistage Néonatal Sanguin, CHU de Québec-Université Laval, Québec City, Québec, Canada
| | - Yves Giguère
- Programme québécois de Dépistage Néonatal Sanguin, CHU de Québec-Université Laval, Québec City, Québec, Canada
| | - Paula J Waters
- Service de Génétique médicale, Département de Pédiatrie, Centre hospitalier universitaire de Sherbrooke (CHUS), Sherbrooke, Québec, Canada
| | - Grant A Mitchell
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada
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Lévesque S, Auray-Blais C, Gravel E, Boutin M, Dempsey-Nunez L, Jacques PE, Chenier S, Larue S, Rioux MF, Al-Hertani W, Nadeau A, Mathieu J, Maranda B, Désilets V, Waters PJ, Keutzer J, Austin S, Kishnani P. Diagnosis of late-onset Pompe disease and other muscle disorders by next-generation sequencing. Orphanet J Rare Dis 2016; 11:8. [PMID: 26809617 PMCID: PMC4727295 DOI: 10.1186/s13023-016-0390-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Accepted: 01/17/2016] [Indexed: 11/16/2022] Open
Abstract
Background Late-onset Pompe disease (LOPD) is a rare treatable lysosomal storage disorder characterized by progressive lysosomal glycogen accumulation and muscle weakness, with often a limb-girdle pattern. Despite published guidelines, testing for LOPD is often overlooked or delayed in adults, owing to its low frequency compared to other muscle disorders with similar muscle patterns. Next-generation sequencing has the capability to test concurrently for several muscle disorders. This could potentially lead to increased diagnosis of LOPD, disorders with non-specific muscle weakness or atypical patients. Methods We developed a gene panel to further study its clinical utility in a cohort of patients with suspected muscle disorders. We designed a gene panel to analyze the coding sequences and splice site junctions of GAA causing LOPD, along with 77 other genes causing muscle disorders with overlapping phenotypes. Results At a median coverage of ~200X (sequences per base), all GAA exons were successfully covered with >20X and only 0.3 % of exons across all genes were <20X. The panel showed an excellent sensitivity (100 %) and specificity (98 %) across all selected genes, using known variations in Pompe patients and controls. We determined its clinical utility by analyzing 34 patients with suspected muscle disorders of undetermined etiology and various muscle patterns, who were referred or followed in neuromuscular and genetics clinics. A putative diagnosis was found in up to 32 % of patients. The gene panel was instrumental in reaching a diagnosis in atypical patients, including one LOPD case. Acid alpha-glucosidase activity was used to confirm the molecular results in all patients. Conclusion This work highlights the high clinical utility of gene panels in patients with suspected muscle disorders and its potential to facilitate the diagnosis of patients showing non-specific muscle weakness or atypical phenotypes. We propose that gene panels should be used as a first-tier test in patients with suspected muscle disorders of undetermined etiology, which could further increase overall diagnosis of muscle conditions, and potentially reduce diagnostic delay. Further studies are necessary to determine the impact of first-tier gene panels on diagnostic delay and on treatment outcome for LOPD. Electronic supplementary material The online version of this article (doi:10.1186/s13023-016-0390-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sébastien Lévesque
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada.
| | - Christiane Auray-Blais
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada
| | - Elaine Gravel
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada
| | - Michel Boutin
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada
| | - Laura Dempsey-Nunez
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada
| | - Pierre-Etienne Jacques
- Departments of Biology and Computer Science, Faculty of Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Sébastien Chenier
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada
| | - Sandrine Larue
- Department of Neurology, Notre-Dame Hospital, Université de Montréal, Montreal, QC, Canada
| | - Marie-France Rioux
- Department of Neurology, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Walla Al-Hertani
- Department of Pediatrics, Cumming School of Medicine, University of Calgary, and Alberta Children's Hospital, Calgary, AB, Canada
| | - Amelie Nadeau
- Department of Pediatrics, Division of Pediatric Neurology, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Jean Mathieu
- Neuromuscular Clinic, Centre de réadaptation en déficience physique de Jonquière, Saguenay, QC, Canada
| | - Bruno Maranda
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada
| | - Valérie Désilets
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada
| | - Paula J Waters
- Department of Pediatrics, Division of Medical Genetics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, and Centre Hospitalier Universitaire de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, QC, J1H 5N4, Canada
| | - Joan Keutzer
- Genzyme Corporation, a Sanofi Company, Cambridge, MA, USA
| | - Stephanie Austin
- Department of Pediatrics, Division of Medical Genetics, Duke University Medical Center, Durham, NC, USA
| | - Priya Kishnani
- Department of Pediatrics, Division of Medical Genetics, Duke University Medical Center, Durham, NC, USA
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Horvath GA, Ye R, Stockler-Ipsiroglu S, Waters PJ, Blakely RD, Coulter-Mackie M. MG-142 Improved motor function with 5-hydroxytryptophan in a family with systemic serotonin deficiency, hemiplegic migraines and neurodegenerative course. J Med Genet 2015. [DOI: 10.1136/jmedgenet-2015-103577.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Braun RJ, Dumit VI, Monpays C, Roucou X, Serrano D, St-Pierre J, Waters PJ, Bates I, Gris D. Struggling for breath in Sherbrooke - 1st Symposium on "One mitochondrion, many diseases" in Sherbrooke, Québec, Canada, March 11th, 2015. Microb Cell 2015; 2:208-213. [PMID: 28357294 PMCID: PMC5349142 DOI: 10.15698/mic2015.06.207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Ralf J Braun
- Institute of Cell Biology, University of Bayreuth, 95440 Bayreuth, Germany
| | - Verónica I Dumit
- ZBSA Center for Biological Systems Analysis, Core Facility Proteomics, University of Freiburg, Freiburg, Germany. ; Department of Dermatology, Medical Center - University of Freiburg, Freiburg, Germany
| | - Cécile Monpays
- Department of Pharmacology and Physiology, University of Sherbrooke Hospital Centre (CHUS), Sherbrooke, QC, Canada
| | - Xavier Roucou
- Department of Biochemistry, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Daniel Serrano
- Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Julie St-Pierre
- Goodmann Cancer Research Centre & Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Paula J Waters
- Medical Genetics Service, Department of Pediatrics, University of Sherbrooke Hospital Centre (CHUS), Sherbrooke, QC, Canada
| | - Ian Bates
- Carl Zeiss Canada MicroImaging, Toronto, ON, Canada
| | - Denis Gris
- Program of Immunology, Department of Pediatrics, CR-CHUS, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada
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Waters PJ, You L, Phommarinh K, Yak S, El Tarazi S, Berthier MT, Giguère Y, Gagnon T, Cyr D, Al-Hertani W. A newborn with persistent mild elevations of succinylacetone in bloodspot, plasma and urine, without identified mutations in the FAH gene. Clin Biochem 2014. [DOI: 10.1016/j.clinbiochem.2014.07.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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15
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Mills PB, Footitt EJ, Ceyhan S, Waters PJ, Jakobs C, Clayton PT, Struys EA. Urinary AASA excretion is elevated in patients with molybdenum cofactor deficiency and isolated sulphite oxidase deficiency. J Inherit Metab Dis 2012; 35:1031-6. [PMID: 22403017 DOI: 10.1007/s10545-012-9466-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 01/18/2012] [Accepted: 02/09/2012] [Indexed: 11/27/2022]
Abstract
Analysis of α-aminoadipic semialdehyde is an important tool in the diagnosis of antiquitin deficiency (pyridoxine-dependent epilepsy). However continuing use of this test has revealed that elevated urinary excretion of α-aminoadipic semialdehyde is not only found in patients with pyridoxine-dependent epilepsy but is also seen in patients with molybdenum cofactor deficiency and isolated sulphite oxidase deficiency. This should be taken into account when interpreting the laboratory data. Sulphite was shown to inhibit α-aminoadipic semialdehyde dehydrogenase in vitro.
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Affiliation(s)
- Philippa B Mills
- Clinical and Molecular Genetics Unit, Institute of Child Health, University College London with Great Ormond Street Hospital for Children NHS Trust, London, WC1N 1EH, UK.
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Roefs AM, Waters PJ, Moore GRW, Dolman PJ. Orbicularis oculi muscle biopsies for mitochondrial DNA analysis in suspected mitochondrial myopathy. Br J Ophthalmol 2012; 96:1296-9. [DOI: 10.1136/bjophthalmol-2012-301853] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Coulter-Mackie MB, Li A, Lian Q, Struys E, Stockler S, Waters PJ. Overexpression of human antiquitin in E. coli: enzymatic characterization of twelve ALDH7A1 missense mutations associated with pyridoxine-dependent epilepsy. Mol Genet Metab 2012; 106:478-81. [PMID: 22784480 DOI: 10.1016/j.ymgme.2012.06.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 06/14/2012] [Accepted: 06/14/2012] [Indexed: 11/19/2022]
Abstract
Pyridoxine dependent epilepsy is an autosomal recessive disorder characterized by early onset seizures responsive to pyridoxine and caused by a defect in the α-aminoadipic semialdehyde dehydrogenase (antiquitin) gene (ALDH7A1). In order to characterize the effects of a series of twelve disease-associated ALDH7A1 missense mutations on antiquitin activity, we generated the mutations in a recombinant human antiquitin cDNA and expressed them in Escherichia coli. We developed an automated spectrophotometric assay of antiquitin enzymatic activity using the natural substrate α-aminoadipic semialdehyde. The substrate was generated using a recombinant lysine aminotransferase gene (lat) from Streptomyces clavuligerus. In the E. coli expression system all the mutants were stably expressed but lacked enzymatic activity. This is consistent with pathogenicity of these mutations in vivo.
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Mercimek-Mahmutoglu S, Horvath GA, Coulter-Mackie M, Nelson T, Waters PJ, Sargent M, Struys E, Jakobs C, Stockler-Ipsiroglu S, Connolly MB. Profound neonatal hypoglycemia and lactic acidosis caused by pyridoxine-dependent epilepsy. Pediatrics 2012; 129:e1368-72. [PMID: 22529283 DOI: 10.1542/peds.2011-0123] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Pyridoxine-dependent epilepsy (PDE) was first described in 1954. The ALDH7A1 gene mutations resulting in α-aminoadipic semialdehyde dehydrogenase deficiency as a cause of PDE was identified only in 2005. Neonatal epileptic encephalopathy is the presenting feature in >50% of patients with classic PDE. We report the case of a 13-month-old girl with profound neonatal hypoglycemia (0.6 mmol/L; reference range >2.4), lactic acidosis (11 mmol/L; reference range <2), and bilateral symmetrical temporal lobe hemorrhages and thalamic changes on cranial MRI. She developed multifocal and myoclonic seizures refractory to multiple antiepileptic drugs that responded to pyridoxine. The diagnosis of α-aminoadipic semialdehyde dehydrogenase deficiency was confirmed based on the elevated urinary α-aminoadipic semialdehyde excretion, compound heterozygosity for a known splice mutation c.834G>A (p.Val278Val), and a novel putative pathogenic missense mutation c.1192G>C (p.Gly398Arg) in the ALDH7A1 gene. She has been seizure-free since 1.5 months of age on treatment with pyridoxine alone. She has motor delay and central hypotonia but normal language and social development at the age of 13 months. This case is the first description of a patient with PDE due to mutations in the ALDH7A1 gene who presented with profound neonatal hypoglycemia and lactic acidosis masquerading as a neonatal-onset gluconeogenesis defect. PDE should be included in the differential diagnosis of hypoglycemia and lactic acidosis in addition to medically refractory neonatal seizures.
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Affiliation(s)
- Saadet Mercimek-Mahmutoglu
- Division of Biochemical Diseases, Department of Pediatrics, University of British Columbia, Vancouver, Canada.
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19
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Waters PJ, McKeon A, Leite MI, Rajasekharan S, Lennon VA, Villalobos A, Palace J, Mandrekar JN, Vincent A, Bar-Or A, Pittock SJ. Serologic diagnosis of NMO: a multicenter comparison of aquaporin-4-IgG assays. Neurology 2012; 78:665-71; discussion 669. [PMID: 22302543 DOI: 10.1212/wnl.0b013e318248dec1] [Citation(s) in RCA: 379] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
OBJECTIVES Neuromyelitis optica (NMO) immunoglobulin G (IgG) (aquaporin-4 [AQP4] IgG) is highly specific for NMO and related disorders, and autoantibody detection has become an essential investigation in patients with demyelinating disease. However, although different techniques are now used, no multicenter comparisons have been performed. This study compares the sensitivity and specificity of different assays, including an in-house flow cytometric assay and 2 commercial assays (ELISA and transfected cell-based assay [CBA]). METHODS Six assay methods (in-house or commercial) were performed in 2 international centers using coded serum from patients with NMO (35 patients), NMO spectrum disorders (25 patients), relapsing-remitting multiple sclerosis (39 patients), miscellaneous autoimmune diseases (25 patients), and healthy subjects (22 subjects). RESULTS The highest sensitivities were yielded by assays detecting IgG binding to cells expressing recombinant AQP4 with quantitative flow cytometry (77; 46 of 60) or visual observation (CBA, 73%; 44 of 60). The fluorescence immunoprecipitation assay and tissue-based immunofluorescence assay were least sensitive (48%-53%). The CBA and ELISA commercial assays (100% specific) yielded sensitivities of 68% (41 of 60) and 60% (36 of 60), respectively, and sensitivity of 72% (43 of 60) when used in combination. CONCLUSIONS The greater sensitivity and excellent specificity of second-generation recombinant antigen-based assays for detection of NMO-IgG in a clinical setting should enable earlier diagnosis of NMO spectrum disorders and prompt initiation of disease-appropriate therapies.
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Affiliation(s)
- P J Waters
- Neuroimmunology Group, Nuffield Department of Clinical Neurosciences, Oxford, UK.
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20
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Al-Thihli K, Ebrahim H, Hughes DA, Patel M, Tipple M, Salvarinova R, Gardiner J, Vallance H, Waters PJ. A variant of unknown significance in the GLA gene causing diagnostic uncertainty in a young female with isolated hypertrophic cardiomyopathy. Gene 2012; 497:320-2. [PMID: 22336178 DOI: 10.1016/j.gene.2012.01.056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 12/30/2011] [Accepted: 01/21/2012] [Indexed: 10/14/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is genetically heterogeneous, and largely caused by mutations in genes encoding sarcomere proteins. However, GLA mutations causing Fabry disease, an X-linked lysosomal storage disorder, may also present with isolated HCM. As HCM genetic testing panels are increasingly being used clinically, variants of unknown significance (VUS) are encountered, leading to challenges in interpretation. We present an illustrative case: a 10-year-old girl with isolated HCM who, on testing with a HCM multi-gene panel, was found to carry a maternally inherited p.W24R variant in GLA. Attempts to evaluate the significance of this variant, by direct biochemical testing of patient specimens, gave inconclusive results. Subsequent in vitro protein expression studies suggested that the variant is unlikely to be pathogenic. This case highlights diagnostic dilemmas that can be provoked by VUS in general, and specifically raises a question whether GLA sequencing should be included in first-line diagnostic testing for female children with isolated hypertrophic cardiomyopathy.
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Affiliation(s)
- Khalid Al-Thihli
- Biochemical Diseases Clinical Service, BC Children's Hospital, Vancouver, BC, Canada.
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21
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Horvath GA, Selby K, Poskitt K, Hyland K, Waters PJ, Coulter-Mackie M, Stockler-Ipsiroglu SG. Hemiplegic migraine, seizures, progressive spastic paraparesis, mood disorder, and coma in siblings with low systemic serotonin. Cephalalgia 2011; 31:1580-6. [DOI: 10.1177/0333102411420584] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background: Serotonin has an important role in vascular resistance and blood pressure control, and a functional serotonin transporter polymorphism has been associated with migraine. Disturbances in serotonin metabolism have been associated with autism, depression, and myoclonus related conditions, but serotonin has far more functions in the body. Familial hemiplegic migraine is a rare autosomal dominant subtype of migraine with aura in which attacks are associated with hemiparesis. Cases: We present two siblings with hemiplegic migraine, depression, progressive spastic paraparesis, myelopathy, and spinal cord atrophy. One of the sisters presented with prolonged coma after a migraine episode. Both sisters were found to have low cerebrospinal fluid serotonin metabolite (5-hydroxyindoleacetic acid), low platelet serotonin levels, and diminished serotonin transport capacity. Their clinical symptoms improved on 5-hydroxytryptophan replacement therapy. Mutational analysis of the CACNA1A and ATP1A2 genes was negative. Conclusion: This is the first time that systemic serotonin deficiency has been described in familial hemiplegic migraine. We hypothesize that the deficiency of serotonin transport may be part of a complex cellular membrane trafficking dysfunction involving not only the serotonin transporter but also other transporters and ion channels.
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Affiliation(s)
| | | | - Ken Poskitt
- British Columbia Children's Hospital, Canada
| | | | - Paula J Waters
- British Columbia Children's Hospital, Canada
- University of British Columbia, Canada
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22
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Van Karnebeek CDM, Waters PJ, Sargent MA, Mezei MM, Wong LJ, Wang J, Stöckler-Ipsiroglu S, Stöckler-Ipsiroglu S. Expanding the clinical phenotype of the mitochondrial m.13513G>A mutation with the first report of a fatal neonatal presentation. Dev Med Child Neurol 2011; 53:565-8. [PMID: 21518340 DOI: 10.1111/j.1469-8749.2010.03907.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Diagnosis of mitochondrial disease is often a challenge because of the extreme heterogeneity of the clinical phenotype and the variety of underlying gene defects. Insight into the range of clinical phenotypes associated with a particular mitochondrial DNA mutation will facilitate better recognition of patients at risk by focused gene testing. We present a family affected by the mitochondrial m.13513G>A (p.D393N, ND5) mutation, illustrating a previously unreported degree of clinical heterogeneity, varying from mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) in a 10-year-old female, to a fatal neonatal course with metabolic acidosis and hypotonia in a younger sister, to absence of medical problems in the mother. The mutation loads ranging from 66% in the deceased neonate to 30% in the female with MELAS and 7% in the asymptomatic mother, correlated with severity of the clinical phenotype. The importance of proactive collection and storage of appropriate samples during the diagnostic work-up of an acutely ill or deceased neonate, allowing subsequent mitochondrial investigations, is hereby illustrated.
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Affiliation(s)
- Clara D M Van Karnebeek
- Division of Biochemical Diseases, Department of Pediatrics, British Columbia Children's Hospital/University of British Columbia, Vancouver, BC, Canada
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23
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Alfadhel M, Lillquist YP, Waters PJ, Sinclair G, Struys E, McFadden D, Hendson G, Hyams L, Shoffner J, Vallance HD. Infantile cardioencephalopathy due to a COX15 gene defect: Report and review. Am J Med Genet A 2011; 155A:840-4. [DOI: 10.1002/ajmg.a.33881] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 12/09/2010] [Indexed: 11/10/2022]
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24
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McLarren KW, Severson TM, du Souich C, Stockton DW, Kratz LE, Cunningham D, Hendson G, Morin RD, Wu D, Paul JE, An J, Nelson TN, Chou A, DeBarber AE, Merkens LS, Michaud JL, Waters PJ, Yin J, McGillivray B, Demos M, Rouleau GA, Grzeschik KH, Smith R, Tarpey PS, Shears D, Schwartz CE, Gecz J, Stratton MR, Arbour L, Hurlburt J, Van Allen MI, Herman GE, Zhao Y, Moore R, Kelley RI, Jones SJM, Steiner RD, Raymond FL, Marra MA, Boerkoel CF. Hypomorphic temperature-sensitive alleles of NSDHL cause CK syndrome. Am J Hum Genet 2010; 87:905-14. [PMID: 21129721 DOI: 10.1016/j.ajhg.2010.11.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 10/31/2010] [Accepted: 11/10/2010] [Indexed: 12/28/2022] Open
Abstract
CK syndrome (CKS) is an X-linked recessive intellectual disability syndrome characterized by dysmorphism, cortical brain malformations, and an asthenic build. Through an X chromosome single-nucleotide variant scan in the first reported family, we identified linkage to a 5 Mb region on Xq28. Sequencing of this region detected a segregating 3 bp deletion (c.696_698del [p.Lys232del]) in exon 7 of NAD(P) dependent steroid dehydrogenase-like (NSDHL), a gene that encodes an enzyme in the cholesterol biosynthesis pathway. We also found that males with intellectual disability in another reported family with an NSDHL mutation (c.1098 dup [p.Arg367SerfsX33]) have CKS. These two mutations, which alter protein folding, show temperature-sensitive protein stability and complementation in Erg26-deficient yeast. As described for the allelic disorder CHILD syndrome, cells and cerebrospinal fluid from CKS patients have increased methyl sterol levels. We hypothesize that methyl sterol accumulation, not only cholesterol deficiency, causes CKS, given that cerebrospinal fluid cholesterol, plasma cholesterol, and plasma 24S-hydroxycholesterol levels are normal in males with CKS. In summary, CKS expands the spectrum of cholesterol-related disorders and insight into the role of cholesterol in human development.
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25
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Wong LJC, Naviaux RK, Brunetti-Pierri N, Zhang Q, Schmitt ES, Truong C, Milone M, Cohen BH, Wical B, Ganesh J, Basinger AA, Burton BK, Swoboda K, Gilbert DL, Vanderver A, Saneto RP, Maranda B, Arnold G, Abdenur JE, Waters PJ, Copeland WC. Molecular and clinical genetics of mitochondrial diseases due to POLG mutations. Hum Mutat 2010; 29:E150-72. [PMID: 18546365 DOI: 10.1002/humu.20824] [Citation(s) in RCA: 201] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mutations in the POLG gene have emerged as one of the most common causes of inherited mitochondrial disease in children and adults. They are responsible for a heterogeneous group of at least 6 major phenotypes of neurodegenerative disease that include: 1) childhood Myocerebrohepatopathy Spectrum disorders (MCHS), 2) Alpers syndrome, 3) Ataxia Neuropathy Spectrum (ANS) disorders, 4) Myoclonus Epilepsy Myopathy Sensory Ataxia (MEMSA), 5) autosomal recessive Progressive External Ophthalmoplegia (arPEO), and 6) autosomal dominant Progressive External Ophthalmoplegia (adPEO). Due to the clinical heterogeneity, time-dependent evolution of symptoms, overlapping phenotypes, and inconsistencies in muscle pathology findings, definitive diagnosis relies on the molecular finding of deleterious mutations. We sequenced the exons and flanking intron region from approximately 350 patients displaying a phenotype consistent with POLG related mitochondrial disease and found informative mutations in 61 (17%). Two mutant alleles were identified in 31 unrelated index patients with autosomal recessive POLG-related disorders. Among them, 20 (67%) had Alpers syndrome, 4 (13%) had arPEO, and 3 (10%) had ANS. In addition, 30 patients carrying one altered POLG allele were found. A total of 25 novel alterations were identified, including 6 null mutations. We describe the predicted structural/functional and clinical importance of the previously unreported missense variants and discuss their likelihood of being pathogenic. In conclusion, sequence analysis allows the identification of mutations responsible for POLG-related disorders and, in most of the autosomal recessive cases where two mutant alleles are found in trans, finding deleterious mutations can provide an unequivocal diagnosis of the disease.
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Affiliation(s)
- Lee-Jun C Wong
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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26
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Mercimek-Mahmutoglu S, Reilly C, Human D, Waters PJ, Stoeckler-Ipsiroglu S. Progression of organ manifestations upon enzyme replacement therapy in a patient with mucopolysaccharidosis type I/Hurler. World J Pediatr 2009; 5:319-21. [PMID: 19911152 DOI: 10.1007/s12519-009-0062-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Accepted: 04/15/2009] [Indexed: 11/24/2022]
Abstract
BACKGROUND Enzyme replacement therapy (ERT) has been increasingly used as an interim treatment in severe mucopolysaccharidosis type I (MPSI)/Hurler patients prior to hematopoietic stem cell transplantation (HSCT). METHODS We present the outcome of a patient with MPSI/Hurler after 14 months of ERT prior to HSCT. RESULTS Urinary glucosaminoglycan excretion decreased by 70% after one month of ERT. Liver volume decreased by 14% of baseline after 12 months of ERT. Pre-existing thoracolumbar kyphosis progressed to thoracolumbar dislocation with complete displacement of facets after 12 months of ERT. New development of mitral valve thickening was found by echocardiography and mild hearing loss progressed to severe sensorineural hearing loss after 13 months of ERT. CONCLUSIONS ERT over a period of 14 months did not prevent progression of organ manifestations in our patient. Patients should be monitored every 6 months for cardiac, skeletal and audiological involvement on ERT.
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Affiliation(s)
- Saadet Mercimek-Mahmutoglu
- Division of Biochemical Diseases, Department of Pediatrics, British Columbia Children's Hospital, Vancouver, Canada.
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27
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Lehman AM, Schultz KR, Poskitt K, Bjornson B, Keyes R, Waters PJ, Clarke LA, Everett R, McConnell D, Stockler S. Intracranial calcification after cord blood neonatal transplantation for krabbe disease. Neuropediatrics 2009; 40:189-91. [PMID: 20135576 DOI: 10.1055/s-0029-1243189] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Infantile-onset Krabbe disease results from a deficiency of the lysosomal enzyme galactocerebrosidase and leads to death from profound central and peripheral demyelination. Neonatal hematopoietic cell transplantation may result in near-normal cognitive development and partial rescue of gross motor development. The long-term course of the disorder for treated patients seems to involve slowly progressive neurological impairment. We describe the detailed 3-year outcomes of this experimental procedure using umbilical cord blood in a prenatally-diagnosed newborn with Krabbe disease. Substantial perivascular calcifications and atrophy of the white matter developed in the first year post-transplantation. Despite persistent neuroradiological and electrophysiological evidence of leukodystrophy, at age 3 years she has had only mildly impaired non-motor development and moderately impaired motor skills. The cause of these severe white matter changes may have been due to ongoing Krabbe disease or to effects of the chemotherapy regimen or to an interaction of these factors. Extended long-term follow-up of children neonatally transplanted for Krabbe disease is needed before the full utility and limitations of neonatal transplantation can be determined.
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Affiliation(s)
- A M Lehman
- Department of Medical Genetics, British Columbia Children's Hospital, University of British Columbia, Vancouver, Canada
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28
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Rosenberg EH, Struys EA, Hyland K, Plecko B, Waters PJ, Mercimek-Mahmutoglu S, Stockler-Ipsiroglu S, Gallagher RC, Scharer G, Van Hove JLK, Jakobs C, Salomons GS. Mutation detection in DNA isolated from cerebrospinal fluid and urine: Clinical utility and pitfalls of multiple displacement amplification. Mol Genet Metab 2009; 97:312-4. [PMID: 19501531 DOI: 10.1016/j.ymgme.2009.05.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 05/01/2009] [Accepted: 05/02/2009] [Indexed: 11/15/2022]
Abstract
This study describes the use of cerebral spinal fluid (CSF) and/or urine as source of DNA for mutation analysis combined with multiple displacement amplification. The findings illustrate the opportunities and pitfalls of these methods in the search for identification of the pathogenic mutations in the case that only scarce material is available such as CSF.
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Affiliation(s)
- Efraim H Rosenberg
- Metabolic Unit, Department of Clinical Chemistry, VU University Medical Center (PK 1 X009), 1081 HV Amsterdam, The Netherlands
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29
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Gallagher RC, Van Hove JLK, Scharer G, Hyland K, Plecko B, Waters PJ, Mercimek-Mahmutoglu S, Stockler-Ipsiroglu S, Salomons GS, Rosenberg EH, Struys EA, Jakobs C. Folinic acid-responsive seizures are identical to pyridoxine-dependent epilepsy. Ann Neurol 2009; 65:550-6. [DOI: 10.1002/ana.21568] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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30
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Greenberg CR, Dilling LA, Thompson GR, Seargeant LE, Haworth JC, Phillips S, Chan A, Vallance HD, Waters PJ, Sinclair G, Lillquist Y, Wanders RJA, Olpin SE. The paradox of the carnitine palmitoyltransferase type Ia P479L variant in Canadian Aboriginal populations. Mol Genet Metab 2009; 96:201-7. [PMID: 19217814 DOI: 10.1016/j.ymgme.2008.12.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 12/30/2008] [Accepted: 12/30/2008] [Indexed: 10/21/2022]
Abstract
Investigation of seven patients from three families suspected of a fatty acid oxidation defect showed mean CPT-I enzyme activity of 5.9+/-4.9 percent of normal controls. The families, two Inuit, one First Nation, live in areas of Canada geographically very distant from each other. The CPT1 and CPT2 genes were fully sequenced in 5 of the patients. All were homozygous for the same P479L mutation in a highly conserved region of the CPT1 gene. Two patients from the first family were also homozygous for the CPT2 F352C polymorphism in the CPT2 gene. Genotyping the patients and their family members confirmed that all seven patients were homozygous for the P479L variant allele in the CPT1 gene, as were 27 of 32 family members. Three of the seven patients and two cousins had hypoketotic hypoglycemia attributable to CPT-Ia deficiency, but adults homozygous for the variant denied hypoglycemia. We screened 422 consecutive newborns from the region of one of the Inuit families for this variant; 294 were homozygous, 103 heterozygous, and only 25 homozygous normal; thus the frequency of this variant allele is 0.81. There was an infant death in one family and at least 10 more deaths in those infants (7 homozygous, 3 heterozygous) consecutively tested for the mutation at birth. Thus there is an astonishingly high frequency of CPT1 P479L variant and, judging from the enzyme analysis in the seven patients, also CPT-I deficiency in the areas of Canada inhabited by these families. Despite the deficiency of CPT-Ia which is the major rate-limiting enzyme for long chain fatty acid oxidation, clinical effects, with few exceptions, were slight or absent. One clue to explaining this paradox is that, judging from the fatty acid oxidation studies in whole blood and fibroblasts, the low residual activity of CPT-Ia is sufficient to allow a reasonable flux through the mitochondrial oxidation system. It is likely that the P479L variant is of ancient origin and presumably its preservation must have conveyed some advantage.
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Affiliation(s)
- Cheryl R Greenberg
- Department of Pediatrics and Child Health, University of Manitoba, Children's Hospital, CE208-820 Sherbrook Street, Winnipeg, MB, Canada R3A 1R9.
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31
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Wang J, Brautbar A, Chan AK, Dzwiniel T, Li FY, Waters PJ, Graham BH, Wong LJ. Two mtDNA mutations 14487T>C (M63V, ND6) and 12297T>C (tRNA Leu) in a Leigh syndrome family. Mol Genet Metab 2009; 96:59-65. [PMID: 19062322 DOI: 10.1016/j.ymgme.2008.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 10/09/2008] [Accepted: 10/09/2008] [Indexed: 10/21/2022]
Abstract
Mitochondrial cytopathies are characterized by a large variability of clinical phenotypes and severity. The 14487T>C mutation in mtDNA has been recently described to be associated with Leigh syndrome. The 12297T>C mutation has been described in isolated dilated cardiomyopathy patients. Here, we report a family with multiple members who harbor both mutations, with only a few individuals who are affected with Leigh syndrome. Mitochondrial whole genome sequencing analysis in the proband's muscle specimen detected two nearly homoplasmic mutations: 14487T>C (M63V in ND6) and 12297T>C in the tRNA (Leu) (CUN) gene. These two mutations were also detected in the blood, urine sediments, hair follicles, and buccal swab samples of all matrilineal relatives tested. All individuals tested were nearly homoplasmic for the 12297T>C mutation, but had variable degrees of heteroplasmy for 14487T>C. We also screened for the frequency of these two mutations. Of 268 patients with Leigh or Leigh-like disease, one case was found to harbor the 14487T>C mutation (0.3%), and one had the 12297T>C mutation (0.3%). Neither mutation was detected in the 88 patients meeting MELAS syndrome criteria nor in the 56 patients with respiratory chain complex I or I+III deficiency. In conclusion, the 14487T>C mutation appears as the primary etiology of Leigh syndrome in this family, demonstrating the high level of heteroplasmy needed for a clinically significant phenotype with this mutation. The 12297T>C mutation was not associated with dilated cardiomyopathy for the family members who were clinically evaluated and who were shown by testing to be nearly homoplasmic for that mutation.
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Affiliation(s)
- Jing Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, NAB 2015, Houston, TX 77030, USA
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32
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Horvath GA, Davidson AGF, Stockler-Ipsiroglu SG, Lillquist YP, Waters PJ, Olpin S, Andresen BS, Palaty J, Nelson J, Vallance H. Newborn screening for MCAD deficiency: experience of the first three years in British Columbia, Canada. Can J Public Health 2008. [PMID: 18767270 DOI: 10.1007/bf03403754] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND Medium Chain Acyl-CoA Dehydrogenase (MCAD) Deficiency is an autosomal recessive disorder of fatty acid oxidation, with potential fatal outcome. MCAD deficiency is diagnosed by acylcarnitine analysis on newborn screening blood spot cards by tandem mass spectrometry. Early diagnosis of MCAD and presymptomatic treatment can potentially reduce morbidity and mortality. OBJECTIVES To evaluate incidence, clinical outcome, biochemical and molecular phenotype of MCAD cases detected in the first three years of newborn screening in British Columbia (BC). METHODS AND RESULTS Medium chain length acylcarnitines, octanoylcarnitine (C8) and decanoylcarnitine (C10), were measured on newborn screening blood spot cards. Out of 121,000 live births, 17 newborns had C8 values above the screening cut-off of 0.38 umol/L. Ten newborns had elevated C8 on repeat cards and were investigated further. Both C8 and C8/C10 ratios remained abnormal in all confirmed MCAD cases. Positive predictive value of screening was 58% with no false negative results. Seven patients were homozygous for the common c.985A > G MCAD mutation and three others were compound heterozygous for the c.985A > G and a second mutation. Two novel mutations were identified (c.260T > C and c.382T > A). The estimated incidence of MCAD was approximately 1:12,000 live births. Upon frequent feeding and carnitine supplementation, none of the patients had metabolic crises or adverse outcomes. CONCLUSION Frequency of MCAD in BC is comparable to reports from other newborn screening programs. Persistence of elevated C8 levels and C8/C10 ratios in confirmed MCAD cases suggest that these are sensitive markers for newborn screening. Early detection and treatment have successfully prevented adverse health outcomes in patients with MCAD.
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Affiliation(s)
- Gabriella A Horvath
- Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, BC
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Brunetti-Pierri N, Selby K, O'Sullivan M, Hendson G, Truong C, Waters PJ, Wong LJ. Rapidly progressive neurological deterioration in a child with Alpers syndrome exhibiting a previously unremarkable brain MRI. Neuropediatrics 2008; 39:179-83. [PMID: 18991199 DOI: 10.1055/s-0028-1093334] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Alpers syndrome is a fatal disorder due to mutations in the POLG gene encoding the catalytic subunit of mitochondrial DNA polymerase gamma (Pol gamma) involved in mitochondrial DNA (mtDNA) replication. We describe a case of Alpers syndrome due to POLG mutations, with rapidly progressive course, a fatal outcome, and an essentially normal brain MRI in the early oligo-symptomatic phase. Our observation suggests that Alpers syndrome should be considered even in patients with an initially unremarkable brain MRI. The patient was found to harbor the p.Q497H, p.W748S and p.E1143G mutations in cis on one allele, and a fourth mutation, the p.G848S on the other allele. Although the individual mutations detected in the presented case have been previously reported, the specific genotype formed by the particular combination of these is novel.
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Affiliation(s)
- N Brunetti-Pierri
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
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34
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Horvath GA, Stockler-Ipsiroglu SG, Salvarinova-Zivkovic R, Lillquist YP, Connolly M, Hyland K, Blau N, Rupar T, Waters PJ. Autosomal recessive GTP cyclohydrolase I deficiency without hyperphenylalaninemia: evidence of a phenotypic continuum between dominant and recessive forms. Mol Genet Metab 2008; 94:127-31. [PMID: 18276179 DOI: 10.1016/j.ymgme.2008.01.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 01/08/2008] [Indexed: 12/29/2022]
Abstract
We describe a unique presentation of autosomal recessive (AR) GTP cyclohydrolase I (GTPCH) deficiency, with severe CNS involvement but without hyperphenylalaninemia. A male infant presented with progressive spasticity, dystonia and oculogyric episodes. Blood phenylalanine levels were persistently normal: whereas an oral phenylalanine loading test revealed impaired phenylalanine clearance. CSF neopterin and tetrahydrobiopterin (BH(4)) were low, homovanillic acid marginally low and 5-hydroxyindoleacetic acid normal. Fibroblasts showed decreased GTPCH enzyme activity. A homozygous novel mutation of GCH1, p.V206A, was identified. On treatment (BH(4), L-Dopa/Carbidopa and 5-hydroxytryptophan), motor development improved. Mutational analysis provided neonatal diagnosis of a younger brother who, after 18 months on treatment, shows normal development. AR GTPCH I deficiency can present without hyperphenylalaninemia and with normal or subtle CSF neurotransmitter profiles. Testing for GTPCH deficiency should be considered for patients with unexplained neurological symptoms and extrapyramidal movement disorder.
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Affiliation(s)
- Gabriella A Horvath
- Department of Pediatrics, BC's Children's Hospital and University of British Columbia, 4480 Oak Street, Vancouver, BC, Canada
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Coulter-Mackie MB, Lian Q, Applegarth DA, Toone J, Waters PJ, Vallance H. Mutation-based diagnostic testing for primary hyperoxaluria type 1: survey of results. Clin Biochem 2008; 41:598-602. [PMID: 18282470 DOI: 10.1016/j.clinbiochem.2008.01.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 01/17/2008] [Accepted: 01/18/2008] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To test for specific mutations in the alanine:glyoxylate aminotransferase (AGT) gene, in order to diagnose primary hyperoxaluria type 1 (PH1). DESIGN AND METHODS Samples of liver and/or DNA from 81 patients were submitted to our laboratory for diagnostic testing for PH1. Using a panel of selected mutations, DNA was examined in 64 cases, of which 36 had the diagnosis of PH1 confirmed by liver AGT assay. DNA sequencing was employed if mutation testing revealed only one mutation. RESULTS Identification of 100% of the mutations in the AGT-confirmed samples led to the development of a focused testing panel currently involving 4 common mutations, 7 mutations recurring at lower frequency and 5 with apparent ethnic associations. CONCLUSIONS This mutation panel alone would have identified the two causative mutations in 64% of the PH1 samples.
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36
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Andrade J, Waters PJ, Singh RS, Levin A, Toh BC, Vallance HD, Sirrs S. Screening for Fabry disease in patients with chronic kidney disease: limitations of plasma alpha-galactosidase assay as a screening test. Clin J Am Soc Nephrol 2007; 3:139-45. [PMID: 18003767 DOI: 10.2215/cjn.02490607] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND OBJECTIVES Fabry disease is a progressive X-linked disorder of glycosphingolipid metabolism that typically presents in childhood and progresses to heart failure and renal failure in adulthood. This study sought to determine the prevalence of Fabry disease in a multiethnic male chronic kidney disease population, involving dialysis-dependent, non-dialysis-dependent, and transplant patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A total of 499 patients were screened with assay of alpha-galactosidase activity using fluorometric enzyme assay on plasma prepared from fresh heparinized blood, followed by leukocyte alpha-galactosidase activity in the subset of patients with plasma alpha-galactosidase activity below the second percentile (corresponding to a value <3.0 nmol/h per ml plasma). RESULTS This study did not identify any new cases of Fabry disease; however, repeat testing of some of the study patients identified three limitations of the plasma enzyme assay that is commonly used as a high throughput screening method for Fabry disease: (1) False-negative results can occur; (2) these false-negative results are not prevented by use of inhibitors of alpha-galactosidase B activity; and (3) considerable intraindividual variation in plasma alpha-galactosidase levels reduces the discriminatory power of the screening test. CONCLUSION Clinicians need to be aware that screening using plasma will fail to detect some patients with Fabry disease.
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Affiliation(s)
- Jason Andrade
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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Basheer SN, Waters PJ, Lam CW, Acquaviva-Bourdain C, Hendson G, Poskitt K, Hukin J. Isolated sulfite oxidase deficiency in the newborn: lactic acidaemia and leukoencephalopathy. Neuropediatrics 2007; 38:38-41. [PMID: 17607604 DOI: 10.1055/s-2007-981484] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
We report a newborn with progressive leukoencephalopathy and lactic acidaemia, diagnosed with isolated sulfite oxidase deficiency. We show that low plasma total homocysteine (PTHcy) is a valuable early indicator of sulfite oxidase dysfunction, providing a crucial first-line screen, whereas plasma cystine is not always informative in the first few days of life.
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Affiliation(s)
- S N Basheer
- Division of Neurology, British Columbia's Children's Hospital, Vancouver, Canada.
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38
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Waters PJ, Khashu M, Lillquist Y, Senger C, Mattman A, Demos M, Setchell K, Rupar A, Scott P, Blau N, Vallance HD. Neonatal hyperphenylalaninemia, perinatal hemochromatosis, and renal tubulopathy: a unique patient or a novel metabolic disorder? Mol Genet Metab 2005; 86 Suppl 1:S148-52. [PMID: 16182582 DOI: 10.1016/j.ymgme.2005.07.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2005] [Revised: 07/22/2005] [Accepted: 07/25/2005] [Indexed: 01/08/2023]
Abstract
A neonate presented with hyperphenylalaninemia (HPA), with a persistently elevated phenylalanine/tyrosine ratio. The HPA was responsive to tetrahydrobiopterin (BH4). His clinical course was dominated by liver failure, associated with perinatal hemochromatosis. He also developed renal tubulopathy. HPA has not previously been reported in association with any of these features. We investigated the etiology of his condition, and discuss the possibility that this represents a novel single-gene disorder.
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Affiliation(s)
- Paula J Waters
- Department of Pathology and Laboratory Medicine, University of British Columbia, Children's and Women's Health Centre of British Columbia, Vancouver, BC, Canada.
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Demos MK, Waters PJ, Vallance HD, Lillquist Y, Makhseed N, Hyland K, Blau N, Connolly MB. 6-pyruvoyl-tetrahydropterin synthase deficiency with mild hyperphenylalaninemia. Ann Neurol 2005; 58:164-7. [PMID: 15984017 DOI: 10.1002/ana.20532] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Severe 6-pyruvoyl-tetrahydrobiopterin synthase deficiency is a tetrahydrobiopterin deficiency disorder that presents in infancy with developmental delay, seizures, and abnormal movements associated with hyperphenylalaninemia usually detectable by neonatal phenylketonuria screening programs. We describe an 8-year-old girl with delay, seizures, and dystonia with mild hyperphenylalaninemia detected in late childhood. The diagnosis of 6-pyruvoyl-tetrahydrobiopterin synthase deficiency was made by analysis of pterins in urine, pterins and neurotransmitters in cerebrospinal fluid, and enzyme assay. The patient improved clinically taking oral tetrahydrobiopterin, levodopa/carbidopa, and 5-hydroxytryptophan. This treatable condition may not always be detected by routine population screening for hyperphenylalaninemia.
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Affiliation(s)
- Michelle K Demos
- Department of Medical Genetics, University of British Columbia, Children's and Women's Health Centre of British Columbia, Vancouver, Canada.
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40
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Makhseed N, Vallance HD, Potter M, Waters PJ, Wong LTK, Lillquist Y, Pasquali M, Amat di San Filippo C, Longo N. Carnitine transporter defect due to a novel mutation in the SLC22A5 gene presenting with peripheral neuropathy. J Inherit Metab Dis 2004; 27:778-80. [PMID: 15617188 DOI: 10.1023/b:boli.0000045837.23328.f4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The carnitine transporter defect (McKusick 212140) is an autosomal recessive disorder caused by mutations in the SLC22A5 gene, which encodes the high-affinity carnitine transporter OCTN2 (Wang et al 2001). Diagnosis is suspected when plasma carnitine levels are extremely low and secondary causes of carnitine loss are excluded. The disease can present with recurrent Reye-like episodes of hypoketotic hypoglycaemia or with cardiomyopathy associated with myopathy (Stanley et al 1991). Here we report novel clinical findings in a 3-year-old with primary carnitine deficiency.
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Affiliation(s)
- N Makhseed
- Department of Pathology, Children's and Women's Health Center of B.C., Vancouver V6H 3N1, Canada
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41
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Scriver CR, Hurtubise M, Konecki D, Phommarinh M, Prevost L, Erlandsen H, Stevens R, Waters PJ, Ryan S, McDonald D, Sarkissian C. PAHdb 2003: what a locus-specific knowledgebase can do. Hum Mutat 2003; 21:333-44. [PMID: 12655543 DOI: 10.1002/humu.10200] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
PAHdb, a legacy of and resource in genetics, is a relational locus-specific database (http://www.pahdb.mcgill.ca). It records and annotates both pathogenic alleles (n = 439, putative disease-causing) and benign alleles (n = 41, putative untranslated polymorphisms) at the human phenylalanine hydroxylase locus (symbol PAH). Human alleles named by nucleotide number (systematic names) and their trivial names receive unique identifier numbers. The annotated gDNA sequence for PAH is typical for mammalian genes. An annotated gDNA sequence is numbered so that cDNA and gDNA sites are interconvertable. A site map for PAHdb leads to a large array of secondary data (attributes): source of the allele (submitter, publication, or population); polymorphic haplotype background; and effect of the allele as predicted by molecular modeling on the phenylalanine hydroxylase enzyme (EC 1.14.16.1) or by in vitro expression analysis. The majority (63%) of the putative pathogenic PAH alleles are point mutations causing missense in translation of which few have a primary effect on PAH enzyme kinetics. Most apparently have a secondary effect on its function through misfolding, aggregation, and intracellular degradation of the protein. Some point mutations create new splice sites. A subset of primary PAH mutations that are tetrahydrobiopterin-responsive is highlighted on a Curators' Page. A clinical module describes the corresponding human clinical disorders (hyperphenylalaninemia [HPA] and phenylketonuria [PKU]), their inheritance, and their treatment. PAHdb contains data on the mouse gene (Pah) and on four orthologous mutant mouse models and their use (for example, in research on oral treatment of PKU with the enzyme phenylalanine ammonia lyase [EC 4.3.1.5]).
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Affiliation(s)
- Charles R Scriver
- Department of Human Genetics, McGill University Health Centre, Montreal, Canada.
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Abstract
Mutations in the human PAH gene, which encodes phenylalanine hydroxylase are associated with varying degrees of hyperphenylalaninemia (HPA). The more severe of these manifest as a classic metabolic disease--phenylketonuria (PKU). In vitro expression analysis of PAH mutations has three major applications: 1) to confirm that a disease-associated mutation is genuinely pathogenic, 2) to assess the severity of a mutation's impact, and 3) to examine how a mutation exerts its deleterious effects on the PAH enzyme, that is, to elucidate the molecular mechanisms involved. Data on expression analysis of 81 PAH mutations in multiple in vitro systems is summarized in tabular form online at www.pahdb.mcgill.ca. A review of these findings points in particular to a prevalent general mechanism that appears to play a major role in the pathogenicity of many PAH mutations. Amino acid substitutions promote misfolding of the PAH protein monomer and/or oppose the correct assembly of monomers into the native tetrameric enzyme. The resulting structural aberrations trigger cellular defenses, provoking accelerated degradation of the abnormal protein. The intracellular steady-state levels of the mutant PAH enzyme are therefore reduced, leading to an overall decrease in phenylalanine hydroxylation within cells and thus to hyperphenylalaninemia. There is considerable scope for modulation of the enzymic and metabolic phenotypes by modification of the cellular handling--folding, assembly, and degradation--of the mutant PAH protein. This has major implications, both for our understanding of genotype-phenotype correlations and for the development of novel therapeutic approaches.
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Affiliation(s)
- Paula J Waters
- deBelle Laboratory for Biochemical Genetics, Montreal Children's Hospital, Montreal, Quebec, Canada.
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Waters PJ, Scriver CR, Parniak MA. Homomeric and heteromeric interactions between wild-type and mutant phenylalanine hydroxylase subunits: evaluation of two-hybrid approaches for functional analysis of mutations causing hyperphenylalaninemia. Mol Genet Metab 2001; 73:230-8. [PMID: 11461190 DOI: 10.1006/mgme.2001.3198] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phenylketonuria (PKU) is caused by mutations in the phenylalanine hydroxylase gene (PAH), while mutations in genes encoding the two enzymes (dihydropteridine reductase, DHPR, and pterin-4-alpha-carbinolamine dehydratase, PCD) required for recycling of its cofactor, tetrahydrobiopterin (BH(4)), cause other rarer disease forms of hyperphenylalaninemia. We have applied a yeast two-hybrid method, in which protein--protein interactions are measured by four reporter gene constructs, to the analysis of six PKU-associated PAH missense mutations (F39L, K42I, L48S, I65T, A104D, and R157N). By studying homomeric interactions between mutant PAH subunits, we show that this system is capable of detecting quite subtle aberrations in PAH oligomerization caused by missense mutations and that the observed results generally correlate with the severity of the mutation as determined by other expression systems. The mutant PAH subunits are also shown in this system to be able to interact with wild-type PAH subunits, pointing to an explanation for apparent dominant negative effects previously observed in obligate heterozygotes for PKU mutations. Based on our findings, the applications and limitations of two-hybrid approaches in understanding mechanisms by which PAH missense mutations exert their pathogenic effects are discussed. We have also used this technique to demonstrate homomeric interactions between wild-type DHPR subunits and between wild-type PCD subunits. These data provide a basis for functional studies on HPA-associated mutations affecting these enzymes.
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Affiliation(s)
- P J Waters
- deBelle Laboratory for Biochemical Genetics, Montreal Children's Hospital, Quebec, Canada.
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Waters PJ. Degradation of mutant proteins, underlying "loss of function" phenotypes, plays a major role in genetic disease. Curr Issues Mol Biol 2001; 3:57-65. [PMID: 11488412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Many Mendelian monogenic disorders are caused by loss of the function of a single protein. This can result from rapid degradation of the mutant protein by cellular proteases, which reduces the steady-state concentration of the protein within the cell. The susceptibility of a protein to such proteolytic breakdown depends upon its kinetics of monomer folding and oligomer assembly and upon the intrinsic (thermodynamic) stability of its functional native-state conformation. Other cellular proteins, notably molecular chaperones, promote correct protein folding and assembly and thus provide some protection against degradation. An accumulation of recent evidence indicates that premature or accelerated degradation of mutant proteins, provoked by aberrations in their conformation, occurs in various subcellular compartments and represents a significant and prevalent pathogenic mechanism underlying genetic diseases. Inter-individual variability in proteolytic and folding systems can in part explain why "simple monogenic diseases" often display inconsistent genotype-phenotype correlations which show these disorders to be in reality quite complex. Protein folding and degradation may also be modulated artificially using exogenous small molecules. The identification or design of compounds which can interact specifically with particular target proteins, and which in so doing can exert beneficial effects on protein folding, assembly and/or stability, is beginning to open up a new and remarkably promising avenue for the treatment of diverse genetic disorders.
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Affiliation(s)
- P J Waters
- Department of Human Genetics, McGill University-Montreal Children's Hospital Research Institute, Westmount, Quebec, Canada.
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45
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Abstract
Mutations in the human phenylalanine hydroxylase gene (PAH) altering the expressed cDNA nucleotide sequence (GenBank U49897) can impair activity of the corresponding enzyme product (hepatic phenylalanine hydroxylase, PAH) and cause hyperphenylalaninemia (HPA), a metabolic phenotype for which the major disease form is phenylketonuria (PKU; OMIM 261600). In vitro expression analysis of inherited human mutations in eukaryotic, prokaryotic, and cell-free systems is informative about the mechanisms of mutation effects on enzymatic activity and their predicted effect on the metabolic phenotype. Corresponding analysis of site-directed mutations in rat Pah cDNA has assigned critical functional roles to individual amino acid residues within the best understood species of phenylalanine hydroxylase. Data on in vitro expression of 35 inherited human mutations and 22 created rat mutations are reviewed here. The core data are accessible at the PAH Mutation Analysis Consortium Web site (http://www.mcgill.ca/pahdb).
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Affiliation(s)
- P J Waters
- Department of Pediatrics, McGill University, Montreal, Quebec, Canada
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46
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Waters PJ, Parniak MA, Hewson AS, Scriver CR. Alterations in protein aggregation and degradation due to mild and severe missense mutations (A104D, R157N) in the human phenylalanine hydroxylase gene (PAH). Hum Mutat 2000; 12:344-54. [PMID: 9792411 DOI: 10.1002/(sici)1098-1004(1998)12:5<344::aid-humu8>3.0.co;2-d] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Phenylalanine hydroxylase (PAH) catalyzes the conversion of phenylalanine to tyrosine; its activity is the major determinant of phenylalanine disposal. Mutations in the corresponding human gene (PAH), which encodes the human hepatic PAH enzyme, result in hyperphenylalaninemia; the resulting phenotypes can range in severity from mild forms of hyperphenylalaninemia with benign outcome to the severe form, phenylketonuria with impaired cognitive development. This paper describes the detailed characterization of two inherited recessive missense mutations in PAH, c.311C-->A (A104D) and [c.470G-->A;c.471A-->C] (R157N), which are associated, respectively, in the homozygous or functionally hemizygous states, with mild and severe metabolic phenotypes. We used three different in vitro PAH expression systems (in Escherichia coli, cell-free rabbit reticulocyte lysates, and human embryonal kidney cells), as well as a unique assay for phenylalanine oxidation in vivo. In each system, we observed alterations of PAH function and physical properties, compared with wild-type enzyme, and differences in relative severity of effects between these two mutations. Pulse-chase experiments showed increased PAH degradation, probably related to observed aberrations in protein folding and altered oligomerization, as a basic mechanism underlying effects of these missense mutations.
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Affiliation(s)
- P J Waters
- de Belle Laboratory for Biochemical Genetics, McGill University-Montreal Children's Hospital Research Institute, Quebec, Canada.
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Waters PJ, Parniak MA, Akerman BR, Scriver CR. Characterization of phenylketonuria missense substitutions, distant from the phenylalanine hydroxylase active site, illustrates a paradigm for mechanism and potential modulation of phenotype. Mol Genet Metab 2000; 69:101-10. [PMID: 10720436 DOI: 10.1006/mgme.2000.2965] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Missense mutations account for 48% of all reported human disease-causing alleles. Since few are predicted to ablate directly an enzyme's catalytic site or other functionally important amino acid residues, how do most missense mutations cause loss of function and lead to disease? The classic monogenic phenotype hyperphenylalaninemia (HPA), manifesting notably as phenylketonuria (PKU), where missense mutations in the PAH gene compose 60% of the alleles impairing phenylalanine hydroxylase (PAH) function, allows us to examine this question. Here we characterize four PKU-associated PAH mutations (F39L, K42I, L48S, I65T), each changing an amino acid distant from the enzyme active site. Using three complementary in vitro protein expression systems, and 3D-structural localization, we demonstrate a common mechanism. PAH protein folding is affected, causing altered oligomerization and accelerated proteolytic degradation, leading to reduced cellular levels of this cytosolic protein. Enzyme specific activity and kinetic properties are not adversely affected, implying that the only way these mutations reduce enzyme activity within cells in vivo is by producing structural changes which provoke the cell to destroy the aberrant protein. The F39L, L48S, and I65T PAH mutations were selected because each is associated with a spectrum of in vivo HPA among patients. Our in vitro data suggest that interindividual differences in cellular handling of the mutant, but active, PAH proteins will contribute to the observed variability of phenotypic severity. PKU thus supports a newly emerging paradigm both for mechanism whereby missense mutations cause genetic disease and for potential modulation of a disease phenotype.
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Affiliation(s)
- P J Waters
- deBelle Laboratory for Biochemical Genetics, Montreal Children's Hospital, Montreal, H3H 1P3, Canada.
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48
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Abstract
PAHdb is an online relational locus-specific "mutation database" (http://www.mcgill.ca/pahdb) for the human phenylalanine hydroxylase gene (symbol PAH) and its associated phenotypes (protein, metabolic, clinical). When combined with associated information (population distribution of allele, haplotype association, etc.) PAHdb functions as a knowledgebase. From the outset, and in the absence of raw data (e.g., sequence gels), PAHdb has instead been an annotated repository of information about mutations maintained by a team of curators. It is also disease-oriented, being focused on a variant phenotype (hyperphenylalaninemia (HPA) and its most important form of disease, phenylketonuria (PKU)) resulting from primary dysfunction of the PAH enzyme (EC 1.14.16.1); it is "patient friendly" in that it contains information for those personally involved with HPA/PKU (MIM# 261600). PAHdb also serves its community through direct interaction.
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Affiliation(s)
- C R Scriver
- Departments of Biology, Human Genetics, Medicine, and Pediatrics, McGill University Health Centre, Montreal, Quebec, Canada.
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49
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Abstract
The classification of genetic disease into chromosomal, monogenic and multifactorial categories is an oversimplification. Phenylketonuria (PKU) is a classic 'monogenic' autosomal recessive disease in which mutation at the human PAH locus was deemed sufficient to explain the impaired function of the enzyme phenylalanine hydroxylase (enzymic phenotype), the attendant hyperphenylalaninemia (metabolic phenotype) and the resultant mental retardation (cognitive phenotype). In the era of molecular genetics, expectations for a consistently close correlation between the mutant genotype and variant phenotype have been somewhat disappointed, and PKU is used here to illustrate how and why this might be the case. So-called monogenic traits do, indeed, conform to long-accepted ideas about the expression of 'major' loci and their importance in determining parameters of phenotype, but the associated features are as complex, in their own ways, as those in so-called complex traits.
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Affiliation(s)
- C R Scriver
- DeBelle Laboratory for Biochemical Genetics, Montreal Children's Hospital, 2300 Tupper Street, Montreal, Quebec, Canada H3H 1P3.
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Waters PJ, Parniak MA, Akerman BR, Jones AO, Scriver CR. Missense mutations in the phenylalanine hydroxylase gene (PAH) can cause accelerated proteolytic turnover of PAH enzyme: a mechanism underlying phenylketonuria. J Inherit Metab Dis 1999; 22:208-12. [PMID: 10384369 DOI: 10.1023/a:1005533825980] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- P J Waters
- deBelle Laboratory, McGill University-Montreal Children's Hospital Research Institute, Quebec, Canada.
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