51
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Contestabile R, di Salvo ML, Bunik V, Tramonti A, Vernì F. The multifaceted role of vitamin B 6 in cancer: Drosophila as a model system to investigate DNA damage. Open Biol 2020; 10:200034. [PMID: 32208818 PMCID: PMC7125957 DOI: 10.1098/rsob.200034] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A perturbed uptake of micronutrients, such as minerals and vitamins, impacts on different human diseases, including cancer and neurological disorders. Several data converge towards a crucial role played by many micronutrients in genome integrity maintenance and in the establishment of a correct DNA methylation pattern. Failure in the proper accomplishment of these processes accelerates senescence and increases the risk of developing cancer, by promoting the formation of chromosome aberrations and deregulating the expression of oncogenes. Here, the main recent evidence regarding the impact of some B vitamins on DNA damage and cancer is summarized, providing an integrated and updated analysis, mainly centred on vitamin B6. In many cases, it is difficult to finely predict the optimal vitamin rate that is able to protect against DNA damage, as this can be influenced by a given individual's genotype. For this purpose, a precious resort is represented by model organisms which allow limitations imposed by more complex systems to be overcome. In this review, we show that Drosophila can be a useful model to deeply understand mechanisms underlying the relationship between vitamin B6 and genome integrity.
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Affiliation(s)
- Roberto Contestabile
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche 'A. Rossi Fanelli', Sapienza Università di Roma, P.le A. Moro, 5, 00185, Roma, Italy
| | - Martino Luigi di Salvo
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche 'A. Rossi Fanelli', Sapienza Università di Roma, P.le A. Moro, 5, 00185, Roma, Italy
| | - Victoria Bunik
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia.,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119991, Russia.,Sechenov Medical University, Sechenov University, 119048 Moscow, Russia
| | - Angela Tramonti
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti and Dipartimento di Scienze Biochimiche 'A. Rossi Fanelli', Sapienza Università di Roma, P.le A. Moro, 5, 00185, Roma, Italy.,Istituto di Biologia e Patologia Molecolari, Consiglio Nazionale delle Ricerche, Pl.e A. Moro, 5, 00185 Roma, Italy
| | - Fiammetta Vernì
- Dipartimento di Biologia e Biotecnologie 'Charles Darwin', Sapienza Università di Roma, Pl.e A. Moro, 5, 00185 Roma, Italy
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52
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Abstract
Developmental and epileptic encephalopathies (DEEs) can be primarily attributed to genetic causes. The genetic landscape of DEEs has been largely shaped by the rise of high-throughput sequencing, which led to the discovery of new DEE-associated genes and helped identify de novo pathogenic variants. We discuss briefly the contribution of de novo variants to DEE and also focus on alternative inheritance models that contribute to DEE. First, autosomal recessive inheritance in outbred populations may have a larger contribution than previously appreciated, accounting for up to 13% of DEEs. A small subset of genes that typically harbor de novo variants have been associated with recessive inheritance, and often these individuals have more severe clinical presentations. Additionally, pathogenic variants in X-linked genes have been identified in both affected males and females, possibly due to a lack of X-chromosome inactivation skewing. Collectively, exome sequencing has resulted in a molecular diagnosis for many individuals with DEE, but this still leaves many cases unsolved. Multiple factors contribute to the missing etiology, including nonexonic variants, mosaicism, epigenetics, and oligogenic inheritance. Here, we focus on the first 2 factors. We discuss the promises and challenges of genome sequencing, which allows for a more comprehensive analysis of the genome, including interpretation of structural and noncoding variants and also yields a high number of de novo variants for interpretation. We also consider the contribution of genetic mosaicism, both what it means for a molecular diagnosis in mosaic individuals and the important implications for genetic counseling.
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Affiliation(s)
- Hannah C Happ
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Gemma L Carvill
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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53
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Chi W, Iyengar ASR, Albersen M, Bosma M, Verhoeven-Duif NM, Wu CF, Zhuang X. Pyridox (am) ine 5'-phosphate oxidase deficiency induces seizures in Drosophila melanogaster. Hum Mol Genet 2020; 28:3126-3136. [PMID: 31261385 DOI: 10.1093/hmg/ddz143] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/31/2019] [Accepted: 06/04/2019] [Indexed: 12/12/2022] Open
Abstract
Pyridox (am) ine 5'-phosphate oxidase (PNPO) is a rate-limiting enzyme in converting dietary vitamin B6 (VB6) to pyridoxal 5'-phosphate (PLP), the biologically active form of VB6 and involved in the synthesis of neurotransmitters including γ-aminobutyric acid (GABA), dopamine, and serotonin. In humans, PNPO mutations have been increasingly identified in neonatal epileptic encephalopathy and more recently also in early-onset epilepsy. Till now, little is known about the neurobiological mechanisms underlying PNPO-deficiency-induced seizures due to the lack of animal models. Previously, we identified a c.95 C>A missense mutation in sugarlethal (sgll)-the Drosophila homolog of human PNPO (hPNPO)-and found mutant (sgll95) flies exhibiting a lethal phenotype on a diet devoid of VB6. Here, we report the establishment of both sgll95 and ubiquitous sgll knockdown (KD) flies as valid animal models of PNPO-deficiency-induced epilepsy. Both sgll95 and sgll KD flies exhibit spontaneous seizures before they die. Electrophysiological recordings reveal that seizures caused by PNPO deficiency have characteristics similar to that in flies treated with the GABA antagonist picrotoxin. Both seizures and lethality are associated with low PLP levels and can be rescued by ubiquitous expression of wild-type sgll or hPNPO, suggesting the functional conservation of the PNPO enzyme between humans and flies. Results from cell type-specific sgll KD further demonstrate that PNPO in the brain is necessary for seizure prevention and survival. Our establishment of the first animal model of PNPO deficiency will lead to better understanding of VB6 biology, the PNPO gene and its mutations discovered in patients, and can be a cost-effective system to test therapeutic strategies.
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Affiliation(s)
- Wanhao Chi
- Committee on Genetics, Genomics and Systems Biology.,Department of Neurobiology, University of Chicago, Chicago, IL, USA
| | - Atulya S R Iyengar
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA, USA
| | - Monique Albersen
- Section Metabolic Diagnostics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, EA, The Netherlands
| | - Marjolein Bosma
- Section Metabolic Diagnostics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, EA, The Netherlands
| | - Nanda M Verhoeven-Duif
- Section Metabolic Diagnostics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, EA, The Netherlands
| | - Chun-Fang Wu
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA, USA
| | - Xiaoxi Zhuang
- Department of Neurobiology, University of Chicago, Chicago, IL, USA
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54
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Jiao X, Xue J, Gong P, Wu Y, Zhang Y, Jiang Y, Yang Z. Clinical and genetic features in pyridoxine-dependent epilepsy: a Chinese cohort study. Dev Med Child Neurol 2020; 62:315-321. [PMID: 31737911 DOI: 10.1111/dmcn.14385] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/18/2019] [Indexed: 01/18/2023]
Abstract
AIM To characterize the clinical and genetic characteristics of a large cohort of patients with pyridoxine-dependent epilepsy (PDE). METHOD We retrospectively collected clinical and genetic information of 33 (15 males, 18 females; mean [SD] age 4y 11mo [2y 5mo]; 1y 3mo-10y 4mo) patients with PDE from 31 unrelated families at a single centre. RESULTS There were many types of seizures, with focal seizures in 32 cases. Dravet syndrome was suspected clinically in two patients. Electroencephalogram (EEG) was normal in seven patients at the initial stage and then in 17 patients during pyridoxine maintenance therapy. Genetic studies revealed 26 kinds of variants in ALDH7A1 and four in PLPBP with 18 variants unreported previously, and 48 ALDH7A1 variants were located in exon 11, 12, 14, and 17 or intron 9 and 11. In addition, three patients carried different exons deletion. Among these, seizures could be controlled for several years in one patient by levetiracetam monotherapy. Another patient remained seizure free for up to 7 months without therapy. All patients received oral pyridoxine treatment, with only one case (with exon 8-13 deletion) showing poor control. INTERPRETATION This study illustrates the range of clinical presentations and genetic causes in PDE, as well as responsiveness to antiepileptic drugs. A relationship between EEG and pyridoxine therapy could be seen in many cases. Seizure control was seen in all with pyridoxine monotherapy except for one patient. WHAT THIS PAPER ADDS There is a parallel relationship between electroencephalogram and pyridoxine therapy in many patients. Patients with pyridoxine-dependent epilepsy may respond well to low-dose pyridoxine.
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Affiliation(s)
- Xianru Jiao
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Jiao Xue
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Pan Gong
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Ye Wu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yuehua Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Zhixian Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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55
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Helbig I, Ellis CA. Personalized medicine in genetic epilepsies - possibilities, challenges, and new frontiers. Neuropharmacology 2020; 172:107970. [PMID: 32413583 DOI: 10.1016/j.neuropharm.2020.107970] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 01/05/2020] [Accepted: 01/16/2020] [Indexed: 12/13/2022]
Abstract
Identifying the optimal treatment based on specific characteristics of each patient is the main promise of precision medicine. In the field of epilepsy, the identification of more than 100 causative genes provides the enticing possibility of treatments targeted to specific disease etiologies. These conditions include classical examples, such as the use of vitamin B6 in antiquitin deficiency or the ketogenic diet in GLUT1 deficiency, where the disease mechanism can be directly addressed by the selection of a specific therapeutic compound. For epilepsies caused by channelopathies there have been advances in understanding how the selection of existing medications can be targeted to the functional consequences of genetic alterations. We discuss the examples of the use of sodium channel blockers such as phenytoin and oxcarbazepine in the sodium channelopathies, quinidine in KCNT1-related epilepsies, and strategies in GRIN-related epilepsies as examples of epilepsy precision medicine. Assessing the clinical response to targeted treatments of these conditions has been complicated by genetic and phenotypic heterogeneity, as well as by various neurological and non-neurological comorbidities. Moving forward, the development of standardized outcome measures will be critical to successful precision medicine trials in complex and heterogeneous disorders like the epilepsies. Finally, we address new frontiers in epilepsy precision medicine, including the need to match the growing volume of genetic data with high-throughput functional assays to assess the functional consequences of genetic variants and the ability to extract clinical data at large scale from electronic medical records and apply quantitative methods based on standardized phenotyping language.
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Affiliation(s)
- Ingo Helbig
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA; The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, USA; Department of Biomedical and Health Informatics (DBHi), Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA; Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104, USA.
| | - Colin A Ellis
- The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, USA; Department of Biomedical and Health Informatics (DBHi), Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA; Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104, USA
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56
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Fux A, Sieber SA. Biochemical and Proteomic Studies of Human Pyridoxal 5'-Phosphate-Binding Protein (PLPBP). ACS Chem Biol 2020; 15:254-261. [PMID: 31825581 PMCID: PMC9558310 DOI: 10.1021/acschembio.9b00857] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The pyridoxal 5′-phosphate-binding protein (PLPBP)
is an
evolutionarily conserved protein linked to pyridoxal 5′-phosphate-binding.
Although mutations in PLPBP were shown to cause vitamin B6-dependent
epilepsy, its cellular role and function remain elusive. We here report
a detailed biochemical investigation of human PLPBP and its epilepsy-causing
mutants by evaluating stability, cofactor binding, and oligomerization.
In this context, chemical cross-linking combined with mass spectrometry
unraveled an unexpected dimeric assembly of PLPBP. Furthermore, the
interaction network of PLPBP was elucidated by chemical cross-linking
paired with co-immunoprecipitation. A mass spectrometric analysis
in a PLPBP knockout cell line resulted in distinct proteomic changes
compared to wild type cells, including upregulation of several cytoskeleton-
and cell division-associated proteins. Finally, transfection experiments
with vitamin B6-dependent epilepsy-causing PLPBP variants indicate
a potential role of PLPBP in cell division as well as proper muscle
function. Taken together, our studies on the structure and cellular
role of human PLPBP enable a better understanding of the physiological
and pathological mechanism of this important protein.
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Affiliation(s)
- Anja Fux
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
| | - Stephan A. Sieber
- Department of Chemistry, Chair of Organic Chemistry II, Center for Integrated Protein Science (CIPSM), Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
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57
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Johnstone DL, Al-Shekaili HH, Tarailo-Graovac M, Wolf NI, Ivy AS, Demarest S, Roussel Y, Ciapaite J, van Roermund CWT, Kernohan KD, Kosuta C, Ban K, Ito Y, McBride S, Al-Thihli K, Abdelrahim RA, Koul R, Al Futaisi A, Haaxma CA, Olson H, Sigurdardottir LY, Arnold GL, Gerkes EH, Boon M, Heiner-Fokkema MR, Noble S, Bosma M, Jans J, Koolen DA, Kamsteeg EJ, Drögemöller B, Ross CJ, Majewski J, Cho MT, Begtrup A, Wasserman WW, Bui T, Brimble E, Violante S, Houten SM, Wevers RA, van Faassen M, Kema IP, Lepage N, Lines MA, Dyment DA, Wanders RJA, Verhoeven-Duif N, Ekker M, Boycott KM, Friedman JM, Pena IA, van Karnebeek CDM. PLPHP deficiency: clinical, genetic, biochemical, and mechanistic insights. Brain 2020; 142:542-559. [PMID: 30668673 DOI: 10.1093/brain/awy346] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 10/30/2018] [Accepted: 11/13/2018] [Indexed: 12/20/2022] Open
Abstract
Biallelic pathogenic variants in PLPBP (formerly called PROSC) have recently been shown to cause a novel form of vitamin B6-dependent epilepsy, the pathophysiological basis of which is poorly understood. When left untreated, the disease can progress to status epilepticus and death in infancy. Here we present 12 previously undescribed patients and six novel pathogenic variants in PLPBP. Suspected clinical diagnoses prior to identification of PLPBP variants included mitochondrial encephalopathy (two patients), folinic acid-responsive epilepsy (one patient) and a movement disorder compatible with AADC deficiency (one patient). The encoded protein, PLPHP is believed to be crucial for B6 homeostasis. We modelled the pathogenicity of the variants and developed a clinical severity scoring system. The most severe phenotypes were associated with variants leading to loss of function of PLPBP or significantly affecting protein stability/PLP-binding. To explore the pathophysiology of this disease further, we developed the first zebrafish model of PLPHP deficiency using CRISPR/Cas9. Our model recapitulates the disease, with plpbp-/- larvae showing behavioural, biochemical, and electrophysiological signs of seizure activity by 10 days post-fertilization and early death by 16 days post-fertilization. Treatment with pyridoxine significantly improved the epileptic phenotype and extended lifespan in plpbp-/- animals. Larvae had disruptions in amino acid metabolism as well as GABA and catecholamine biosynthesis, indicating impairment of PLP-dependent enzymatic activities. Using mass spectrometry, we observed significant B6 vitamer level changes in plpbp-/- zebrafish, patient fibroblasts and PLPHP-deficient HEK293 cells. Additional studies in human cells and yeast provide the first empirical evidence that PLPHP is localized in mitochondria and may play a role in mitochondrial metabolism. These models provide new insights into disease mechanisms and can serve as a platform for drug discovery.
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Affiliation(s)
- Devon L Johnstone
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Hilal H Al-Shekaili
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.,British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada
| | - Maja Tarailo-Graovac
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.,British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada.,Institute of Physiology and Biochemistry, Faculty of Biology, The University of Belgrade, Belgrade, Serbia.,Departments of Biochemistry, Molecular Biology, and Medical Genetics, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Nicole I Wolf
- Department of Child Neurology, Amsterdam University Medical Centres, Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Autumn S Ivy
- Division of Child Neurology, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, CA, USA
| | - Scott Demarest
- Departments of Pediatrics and Neurology, University of Colorado School of Medicine, Children's Hospital Colorado, CO, USA
| | - Yann Roussel
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Jolita Ciapaite
- Department of Genetics, Center for Molecular Medicine, University Medical Center, Utrecht, The Netherlands
| | - Carlo W T van Roermund
- Department of Pediatrics and Clinical Chemistry, Laboratory Division, Laboratory Genetic Metabolic Diseases, Amsterdam University Medical Centres, Amsterdam, The Netherlands
| | - Kristin D Kernohan
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Ceres Kosuta
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Kevin Ban
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Yoko Ito
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Skye McBride
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Khalid Al-Thihli
- Genetic and Developmental Medicine Clinic, Sultan Qaboos University Hospital, Muscat, Oman
| | - Rana A Abdelrahim
- Department of Child Health, Sultan Qaboos University Hospital, Muscat, Oman
| | - Roshan Koul
- Paediatric Neurology Unit, Child Health Department, Sultan Qaboos University Hospital, Muscat, Oman
| | - Amna Al Futaisi
- Paediatric Neurology Unit, Child Health Department, Sultan Qaboos University Hospital, Muscat, Oman
| | - Charlotte A Haaxma
- Department of Pediatric Neurology, Amalia Children's Hospital and Donders Institute of Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Heather Olson
- Department of Neurology, Division of Epilepsy and Clinical Neurophysiology, Boston Children's Hospital, Boston, MA, USA
| | - Laufey Yr Sigurdardottir
- Department of Neurology, University of Central Florida, Nemours Children's Hospital, Orlando, FL, USA
| | - Georgianne L Arnold
- Department of Pediatrics, University of Pittsburgh Medical Center, Pittsburg, PA, USA
| | - Erica H Gerkes
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - M Boon
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - M Rebecca Heiner-Fokkema
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Sandra Noble
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Marjolein Bosma
- Department of Genetics, Center for Molecular Medicine, University Medical Center, Utrecht, The Netherlands
| | - Judith Jans
- Department of Genetics, Center for Molecular Medicine, University Medical Center, Utrecht, The Netherlands.,United for Metabolic Diseases, The Netherlands
| | - David A Koolen
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Britt Drögemöller
- British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada.,Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Colin J Ross
- British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada.,Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Jacek Majewski
- McGill University and Genome Quebec Innovation Centre, Montreal, QC, Canada.,Department of Human Genetics, McGill University, Montreal, QC, Canada
| | | | | | - Wyeth W Wasserman
- British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada
| | - Tuan Bui
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Elise Brimble
- Department of Neurology and Neurological Sciences, Stanford Medicine, Stanford, CA, USA
| | - Sara Violante
- Department of Genetics and Genomic Sciences and Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sander M Houten
- Department of Genetics and Genomic Sciences and Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ron A Wevers
- United for Metabolic Diseases, The Netherlands.,Translational Metabolic Laboratory, Department Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Martijn van Faassen
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Ido P Kema
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Nathalie Lepage
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | | | - Matthew A Lines
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Division of Metabolics and Newborn Screening, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - David A Dyment
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Department of Medical Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Ronald J A Wanders
- Department of Pediatrics and Clinical Chemistry, Laboratory Division, Laboratory Genetic Metabolic Diseases, Amsterdam University Medical Centres, Amsterdam, The Netherlands.,United for Metabolic Diseases, The Netherlands
| | - Nanda Verhoeven-Duif
- Department of Genetics, Center for Molecular Medicine, University Medical Center, Utrecht, The Netherlands.,United for Metabolic Diseases, The Netherlands
| | - Marc Ekker
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Kym M Boycott
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Department of Medical Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Jan M Friedman
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.,British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada
| | - Izabella A Pena
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Clara D M van Karnebeek
- British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada.,United for Metabolic Diseases, The Netherlands.,Departments of Pediatrics and Clinical Genetics, Amsterdam University Medical Centres, Amsterdam, The Netherlands.,Centre for Molecular Medicine and Therapeutics, Department of Pediatrics, University of British Columbia, Vancouver, Canada
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58
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Koul R, Alfutaisi A, Abdelrahim R, Altihilli K. Pyridoxine Responsive Seizures: Beyond Aldehyde Dehydrogenase 7A1. J Neurosci Rural Pract 2019; 10:613-616. [PMID: 31831980 PMCID: PMC6906095 DOI: 10.1055/s-0039-1697775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Objective
Pyridoxine responsive seizures (PDRs) are characterized by early-onset seizures and epileptic encephalopathy (neonates and infants) which respond to pyridoxine. Any type of seizures can be the first presentation of PDRs in these children. The aim of this 20-year retrospective study was to report the profile of 35 children with PDRs.
Materials and Methods
Neonatal and infantile seizures responding to pyridoxine were analyzed retrospectively from 1998 to 2018. Depending on the clinical features, laboratory results, and genetic study, they were divided into following four groups: (A) responders with α-aminoadipic semialdehyde dehydrogenase 7A1 (
ALDH7A1
) mutation, (B) responders with pyridoxal phosphate homeostasis protein (PLPHP) mutation, (C) responders with none of these two known mutations, (D) and responders in combination with antiepileptic medications.
Results
Sixteen of 35 children had genetic mutation, 4 with
ALDH7A1
mutation, and 12 with PLPHP mutation recently described. Nineteen of 35 children had no genetic positivity.
Conclusion
A large number of children with pyridoxine response do not have known genetic confirmation. Over time, new genes, responsible for pyridoxine dependency, may be identified or an unknown metabolic disorder may be seen in these children.
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Affiliation(s)
- Roshan Koul
- Department of Neurology, Institute of Liver and Biliary Sciences, New Delhi, India
| | - Amna Alfutaisi
- Child Neurology, Sultan Qaboos University Hospital, College of Medicine and Health Sciences, Muscat, Oman
| | - Rana Abdelrahim
- Child Neurology, Sultan Qaboos University Hospital, College of Medicine and Health Sciences, Muscat, Oman
| | - Khalid Altihilli
- Department of Genetics, Sultan Qaboos University Hospital, College of Medicine and Health Sciences, Muscat, Oman
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59
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Ito T, Hori R, Hemmi H, Downs DM, Yoshimura T. Inhibition of glycine cleavage system by pyridoxine 5'-phosphate causes synthetic lethality in glyA yggS and serA yggS in Escherichia coli. Mol Microbiol 2019; 113:270-284. [PMID: 31677193 DOI: 10.1111/mmi.14415] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2019] [Indexed: 12/15/2022]
Abstract
The YggS/Ybl036c/PLPBP family includes conserved pyridoxal 5'-phosphate (PLP)-binding proteins that play a critical role in the homeostasis of vitamin B6 and amino acids. Disruption of members of this family causes pleiotropic effects in many organisms by unknown mechanisms. In Escherichia coli, conditional lethality of the yggS and glyA (encoding serine hydroxymethyltransferase) has been described, but the mechanism of lethality was not determined. Strains lacking yggS and serA (3-phosphoglycerate dehydrogenase) were conditionally lethality in the M9-glucose medium supplemented with Gly. Analyses of vitamin B6 pools found the high-levels of pyridoxine 5'-phosphate (PNP) in the two yggS mutants. Growth defects of the double mutants could be eliminated by overexpressing PNP/PMP oxidase (PdxH) to decrease the PNP levels. Further, a serA pdxH strain, which accumulates PNP in the presence of yggS, exhibited similar phenotype to serA yggS mutant. Together these data suggested the inhibition of the glycine cleavage (GCV) system caused the synthetic lethality. Biochemical assays confirmed that PNP disrupts the GCV system by competing with PLP in GcvP protein. Our data are consistent with a model in which PNP-dependent inhibition of the GCV system causes the conditional lethality observed in the glyA yggS or serA yggS mutants.
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Affiliation(s)
- Tomokazu Ito
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, 464-8601, Japan
| | - Ran Hori
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, 464-8601, Japan
| | - Hisashi Hemmi
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, 464-8601, Japan
| | - Diana M Downs
- Department of Microbiology, University of Georgia, Athens, GA, 30602, USA
| | - Tohru Yoshimura
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furou-chou, Chikusa, Nagoya, Aichi, 464-8601, Japan
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Ciapaite J, Albersen M, Savelberg SMC, Bosma M, Tessadori F, Gerrits J, Lansu N, Zwakenberg S, Bakkers JPW, Zwartkruis FJT, van Haaften G, Jans JJ, Verhoeven-Duif NM. Pyridox(am)ine 5'-phosphate oxidase (PNPO) deficiency in zebrafish results in fatal seizures and metabolic aberrations. Biochim Biophys Acta Mol Basis Dis 2019; 1866:165607. [PMID: 31759955 DOI: 10.1016/j.bbadis.2019.165607] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 10/21/2019] [Accepted: 11/01/2019] [Indexed: 02/07/2023]
Abstract
Pyridox(am)ine 5'-phosphate oxidase (PNPO) catalyzes oxidation of pyridoxine 5'-phosphate (PNP) and pyridoxamine 5'-phosphate (PMP) to pyridoxal 5'-phosphate (PLP), the active form of vitamin B6. PNPO deficiency results in neonatal/infantile seizures and neurodevelopmental delay. To gain insight into this disorder we generated Pnpo deficient (pnpo-/-) zebrafish (CRISPR/Cas9 gene editing). Locomotion analysis showed that pnpo-/- zebrafish develop seizures resulting in only 38% of pnpo-/- zebrafish surviving beyond 20 days post fertilization (dpf). The age of seizure onset varied and survival after the onset was brief. Biochemical profiling at 20 dpf revealed a reduction of PLP and pyridoxal (PL) and accumulation of PMP and pyridoxamine (PM). Amino acids involved in neurotransmission including glutamate, γ-aminobutyric acid (GABA) and glycine were decreased. Concentrations of several, mostly essential, amino acids were increased in pnpo-/- zebrafish suggesting impaired activity of PLP-dependent transaminases involved in their degradation. PLP treatment increased survival at 20 dpf and led to complete normalization of PLP, PL, glutamate, GABA and glycine. However, amino acid profiles only partially normalized and accumulation of PMP and PM persisted. Taken together, our data indicate that not only decreased PLP but also accumulation of PMP may play a role in the clinical phenotype of PNPO deficiency.
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Affiliation(s)
- Jolita Ciapaite
- Department of Genetics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands; Center for Molecular Medicine, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands.
| | - Monique Albersen
- Department of Genetics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Sanne M C Savelberg
- Department of Genetics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands; Center for Molecular Medicine, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Marjolein Bosma
- Department of Genetics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Federico Tessadori
- Department of Genetics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands; Center for Molecular Medicine, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands; Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, the Netherlands
| | - Johan Gerrits
- Department of Genetics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Nico Lansu
- Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, the Netherlands
| | - Susan Zwakenberg
- Center for Molecular Medicine, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands; Department of Molecular Cancer Research, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Jeroen P W Bakkers
- Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, the Netherlands; Department of Medical Physiology, University Medical Center Utrecht, 3584 CM Utrecht, the Netherlands
| | - Fried J T Zwartkruis
- Center for Molecular Medicine, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands; Department of Molecular Cancer Research, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Gijs van Haaften
- Department of Genetics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands; Center for Molecular Medicine, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Judith J Jans
- Department of Genetics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands; Center for Molecular Medicine, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
| | - Nanda M Verhoeven-Duif
- Department of Genetics, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands; Center for Molecular Medicine, University Medical Center Utrecht, 3584 EA Utrecht, the Netherlands
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61
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Jensen KV, Frid M, Stödberg T, Barbaro M, Wedell A, Christensen M, Bak M, Ek J, Madsen CG, Darin N, Grønborg S. Diagnostic pitfalls in vitamin B6-dependent epilepsy caused by mutations in the PLPBP gene. JIMD Rep 2019; 50:1-8. [PMID: 31741821 PMCID: PMC6850975 DOI: 10.1002/jmd2.12063] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/04/2019] [Accepted: 06/05/2019] [Indexed: 12/03/2022] Open
Abstract
Vitamin B6-responsive epilepsies are a group of genetic disorders including ALDH7A1 deficiency, PNPO deficiency, and others, usually causing neonatal onset seizures resistant to treatment with common antiepileptic drugs. Recently, biallelic mutations in PLPBP were shown to be a novel cause of vitamin B6-dependent epilepsy with a variable phenotype. The different vitamin B6-responsive epilepsies can be detected and distinguished by their respective biomarkers and genetic analysis. Unfortunately, metabolic biomarkers for early detection and prognosis of PLPBP deficiency are currently still lacking. Here, we present data from two further patients with vitamin B6-dependent seizures caused by variants in PLPBP, including a novel missense variant, and compare their genotype and phenotypic presentation to previously described cases. Hyperglycinemia and hyperlactatemia are the most consistently observed biochemical abnormalities in pyridoxal phosphate homeostasis protein (PLPHP) deficient patients and were present in both patients in this report within the first days of life. Lactic acidemia, the neuroradiological, and clinical presentation led to misdiagnosis of a mitochondrial encephalopathy in two previously published cases with an early fatal course. Similarly, on the background of glycine elevation in plasma, glycine encephalopathy was wrongly adopted as diagnosis for a patient in our report. In this regard, lactic acidemia as well as hyperglycinemia appear to be diagnostic pitfalls in patients with vitamin B6-responsive epilepsies, including PLPHP deficiency. SYNOPSIS In vitamin B6-responsive epilepsies, including PLPHP deficiency, there are several diagnostic pitfalls, including lactic acidemia as well as hyperglycinemia, highlighting the importance of a pyridoxine trial, and genetic testing.
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Affiliation(s)
| | - Maria Frid
- Department of PaediatricsRyhov County HospitalJönköpingSweden
| | - Tommy Stödberg
- Department of Women's and Children's HealthKarolinska InstitutetStockholmSweden
- Neuropaediatric UnitKarolinska University HospitalStockholmSweden
| | - Michela Barbaro
- Centre for Inherited Metabolic DiseasesKarolinska University HospitalStockholmSweden
- Department of Molecular Medicine and SurgeryKarolinska InstitutetStockholmSweden
| | - Anna Wedell
- Centre for Inherited Metabolic DiseasesKarolinska University HospitalStockholmSweden
- Department of Molecular Medicine and SurgeryScience for Life Laboratory, Karolinska InstitutetStockholmSweden
| | - Mette Christensen
- Department of Clinical GeneticsCopenhagen University HospitalCopenhagenDenmark
| | - Mads Bak
- Department of Clinical GeneticsCopenhagen University HospitalCopenhagenDenmark
| | - Jakob Ek
- Department of Clinical GeneticsCopenhagen University HospitalCopenhagenDenmark
| | - Camilla Gøbel Madsen
- Department of Radiology, Centre for Functional and Diagnostic Imaging and ResearchCopenhagen University, Hvidovre HospitalHvidovreDenmark
| | - Niklas Darin
- Department of PediatricsUniversity of Gothenburg, Sahlgrenska University HospitalGothenburgSweden
| | - Sabine Grønborg
- Department of Clinical GeneticsCopenhagen University HospitalCopenhagenDenmark
- Centre for Inherited Metabolic Diseases, Department of PaediatricsCopenhagen University HospitalCopenhagenDenmark
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62
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Barile A, Tramonti A, di Salvo ML, Nogués I, Nardella C, Malatesta F, Contestabile R. Allosteric feedback inhibition of pyridoxine 5'-phosphate oxidase from Escherichia coli. J Biol Chem 2019; 294:15593-15603. [PMID: 31484724 DOI: 10.1074/jbc.ra119.009697] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 09/02/2019] [Indexed: 11/06/2022] Open
Abstract
In Escherichia coli, the synthesis of pyridoxal 5'-phosphate (PLP), the catalytically active form of vitamin B6, takes place through the so-called deoxyxylulose 5-phosphate-dependent pathway, whose last step is pyridoxine 5'-phosphate (PNP) oxidation to PLP, catalyzed by the FMN-dependent enzyme PNP oxidase (PNPOx). This enzyme plays a pivotal role in controlling intracellular homeostasis and bioavailability of PLP. PNPOx has been proposed to undergo product inhibition resulting from PLP binding at the active site. PLP has also been reported to bind tightly at a secondary site, apparently without causing PNPOx inhibition. The possible location of this secondary site has been indicated by crystallographic studies as two symmetric surface pockets present on the PNPOx homodimer, but this site has never been verified by other experimental means. Here, we demonstrate, through kinetic measurements, that PLP inhibition is actually of a mixed-type nature and results from binding of this vitamer at an allosteric site. This interpretation was confirmed by the characterization of a mutated PNPOx form, in which substrate binding at the active site is heavily hampered but PLP binding is preserved. Structural and functional connections between the active site and the allosteric site were indicated by equilibrium binding experiments, which revealed different PLP-binding stoichiometries with WT and mutant PNPOx forms. These observations open up new horizons on the mechanisms that regulate E. coli PNPOx, which may have commonalities with the mechanisms regulating human PNPOx, whose crucial role in vitamin B6 metabolism and epilepsy is well-known.
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Affiliation(s)
- Anna Barile
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli," Sapienza Università di Roma, Laboratory affiliated with Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Angela Tramonti
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli," Sapienza Università di Roma, Laboratory affiliated with Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Piazzale Aldo Moro 5, 00185 Roma, Italy.,Istituto di Biologia e Patologia Molecolari, CNR, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Martino Luigi di Salvo
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli," Sapienza Università di Roma, Laboratory affiliated with Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Isabel Nogués
- Istituto di Ricerca sugli Ecosistemi Terrestri, CNR, Via G. Marconi 2, 05010 Porano (TR), Italy
| | - Caterina Nardella
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli," Sapienza Università di Roma, Laboratory affiliated with Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Francesco Malatesta
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli," Sapienza Università di Roma, Laboratory affiliated with Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Roberto Contestabile
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli," Sapienza Università di Roma, Laboratory affiliated with Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Piazzale Aldo Moro 5, 00185 Roma, Italy
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63
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Tiani KA, Stover PJ, Field MS. The Role of Brain Barriers in Maintaining Brain Vitamin Levels. Annu Rev Nutr 2019; 39:147-173. [DOI: 10.1146/annurev-nutr-082018-124235] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It is increasingly recognized that tissue-specific nutrient deficiencies can exist in the absence of whole-body deficiency and that these deficiencies may result from disease or disease-related physiological processes. Brain and central nervous system tissues require adequate nutrient levels to function. Many nutrients are concentrated in the cerebrospinal fluid relative to the serum in healthy individuals, and other nutrients resist depletion in the presence of whole-body nutrient depletion. The endothelial, epithelial, and arachnoid brain barriers work in concert to selectively transport, concentrate, and maintain levels of the specific nutrients required by the brain while also blocking the passage of blood-borne toxins and pathogens to brain and central nervous system tissues. These barriers preserve nutrient levels within the brain and actively concentrate nutrients within the cerebrospinal fluid and brain. The roles of physical and energetic barriers, including the blood–brain and blood–nerve barriers, in maintaining brain nutrient levels in health and disease are discussed.
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Affiliation(s)
- Kendra A. Tiani
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
| | - Patrick J. Stover
- College of Agriculture and Life Sciences, Texas A & M University, College Station, Texas 77843-2142, USA
| | - Martha S. Field
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA
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64
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Chelban V, Wilson MP, Warman Chardon J, Vandrovcova J, Zanetti MN, Zamba‐Papanicolaou E, Efthymiou S, Pope S, Conte MR, Abis G, Liu Y, Tribollet E, Haridy NA, Botía JA, Ryten M, Nicolaou P, Minaidou A, Christodoulou K, Kernohan KD, Eaton A, Osmond M, Ito Y, Bourque P, Jepson JEC, Bello O, Bremner F, Cordivari C, Reilly MM, Foiani M, Heslegrave A, Zetterberg H, Heales SJR, Wood NW, Rothman JE, Boycott KM, Mills PB, Clayton PT, Houlden H. PDXK mutations cause polyneuropathy responsive to pyridoxal 5'-phosphate supplementation. Ann Neurol 2019; 86:225-240. [PMID: 31187503 PMCID: PMC6772106 DOI: 10.1002/ana.25524] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 06/05/2019] [Accepted: 06/07/2019] [Indexed: 12/30/2022]
Abstract
OBJECTIVE To identify disease-causing variants in autosomal recessive axonal polyneuropathy with optic atrophy and provide targeted replacement therapy. METHODS We performed genome-wide sequencing, homozygosity mapping, and segregation analysis for novel disease-causing gene discovery. We used circular dichroism to show secondary structure changes and isothermal titration calorimetry to investigate the impact of variants on adenosine triphosphate (ATP) binding. Pathogenicity was further supported by enzymatic assays and mass spectroscopy on recombinant protein, patient-derived fibroblasts, plasma, and erythrocytes. Response to supplementation was measured with clinical validated rating scales, electrophysiology, and biochemical quantification. RESULTS We identified biallelic mutations in PDXK in 5 individuals from 2 unrelated families with primary axonal polyneuropathy and optic atrophy. The natural history of this disorder suggests that untreated, affected individuals become wheelchair-bound and blind. We identified conformational rearrangement in the mutant enzyme around the ATP-binding pocket. Low PDXK ATP binding resulted in decreased erythrocyte PDXK activity and low pyridoxal 5'-phosphate (PLP) concentrations. We rescued the clinical and biochemical profile with PLP supplementation in 1 family, improvement in power, pain, and fatigue contributing to patients regaining their ability to walk independently during the first year of PLP normalization. INTERPRETATION We show that mutations in PDXK cause autosomal recessive axonal peripheral polyneuropathy leading to disease via reduced PDXK enzymatic activity and low PLP. We show that the biochemical profile can be rescued with PLP supplementation associated with clinical improvement. As B6 is a cofactor in diverse essential biological pathways, our findings may have direct implications for neuropathies of unknown etiology characterized by reduced PLP levels. ANN NEUROL 2019;86:225-240.
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Affiliation(s)
- Viorica Chelban
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Neurology and NeurosurgeryInstitute of Emergency MedicineChisinauMoldova
| | - Matthew P. Wilson
- Genetics and Genomic MedicineUniversity College London Great Ormond Street Institute of Child HealthLondonUnited Kingdom
| | - Jodi Warman Chardon
- Department of Medicine (Neurology)University of OttawaOttawaOntarioCanada
- Ottawa Hospital Research InstituteOttawaOntarioCanada
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Jana Vandrovcova
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - M. Natalia Zanetti
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Eleni Zamba‐Papanicolaou
- Cyprus Institute of Neurology and GeneticsNicosiaCyprus
- Cyprus School of Molecular MedicineNicosiaCyprus
| | - Stephanie Efthymiou
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Simon Pope
- Neurometabolic Unit, National Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - Maria R. Conte
- Randall Centre of Cell and Molecular Biophysics, School of Basic and Medical BiosciencesKing's College LondonLondonUnited Kingdom
| | - Giancarlo Abis
- Randall Centre of Cell and Molecular Biophysics, School of Basic and Medical BiosciencesKing's College LondonLondonUnited Kingdom
| | - Yo‐Tsen Liu
- Department of NeurologyNeurological Institute, Taipei Veterans General HospitalTaipeiTaiwan
- National Yang‐Ming University School of MedicineTaipeiTaiwan
- Institute of Brain Science, National Yang‐Ming UniversityTaipeiTaiwan
| | - Eloise Tribollet
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Nourelhoda A. Haridy
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Neurology and PsychiatryAssiut University Hospital, Faculty of MedicineAsyutEgypt
| | - Juan A. Botía
- Reta Lila Weston Research LaboratoriesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Information and Communications EngineeringUniversity of MurciaMurciaSpain
| | - Mina Ryten
- Reta Lila Weston Research LaboratoriesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Medical & Molecular GeneticsKing's College London, Guy's HospitalLondonUnited Kingdom
| | - Paschalis Nicolaou
- Cyprus Institute of Neurology and GeneticsNicosiaCyprus
- Cyprus School of Molecular MedicineNicosiaCyprus
| | - Anna Minaidou
- Cyprus Institute of Neurology and GeneticsNicosiaCyprus
- Cyprus School of Molecular MedicineNicosiaCyprus
| | - Kyproula Christodoulou
- Cyprus Institute of Neurology and GeneticsNicosiaCyprus
- Cyprus School of Molecular MedicineNicosiaCyprus
| | - Kristin D. Kernohan
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
- Newborn Screening Ontario, Children's Hospital of Eastern OntarioOttawaOntarioCanada
| | - Alison Eaton
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Matthew Osmond
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Yoko Ito
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Pierre Bourque
- Department of Medicine (Neurology)University of OttawaOttawaOntarioCanada
- Ottawa Hospital Research InstituteOttawaOntarioCanada
| | - James E. C. Jepson
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Oscar Bello
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Fion Bremner
- Neuro‐ophthalmology DepartmentNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - Carla Cordivari
- Clinical Neurophysiology DepartmentNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - Mary M. Reilly
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Martha Foiani
- Clinical Neurophysiology DepartmentNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
- Department of Neurodegenerative DiseaseUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Amanda Heslegrave
- Department of Neurodegenerative DiseaseUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- UK Dementia Research Institute at University College LondonLondonUnited Kingdom
| | - Henrik Zetterberg
- Department of Neurodegenerative DiseaseUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- UK Dementia Research Institute at University College LondonLondonUnited Kingdom
- Clinical Neurochemistry LaboratorySahlgrenska University HospitalMölndalSweden
- Department of Psychiatry and NeurochemistryInstitute of Neuroscience and Physiology, Sahlgrenska Academy at University of GothenburgMölndalSweden
| | - Simon J. R. Heales
- Neurometabolic Unit, National Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - Nicholas W. Wood
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Neurogenetics LaboratoryNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - James E. Rothman
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Cell BiologyYale School of MedicineNew HavenCT
| | - Kym M. Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Philippa B. Mills
- Genetics and Genomic MedicineUniversity College London Great Ormond Street Institute of Child HealthLondonUnited Kingdom
| | - Peter T. Clayton
- Genetics and Genomic MedicineUniversity College London Great Ormond Street Institute of Child HealthLondonUnited Kingdom
| | - Henry Houlden
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Neurogenetics LaboratoryNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
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Abstract
Introduction: Vitamin B6 dependent epilepsies are a group of treatable diseases (ALDH7A1 deficiency, PNPO deficiency, PLP binding protein deficiency, hyperprolinaemia type II and hypophosphatasia and glycosylphosphatidylinositol anchor synthesis defects) responding to pyridoxine or pyridoxal-5I-phosphate. Areas covered: A critical review was conducted on the therapeutic management of all the reported patients with genetically confirmed diagnoses of diseases affecting vitamin B6 metabolism and presenting with pyridoxine or pyridoxal-5I-phosphate dependent-seizures. Data about safety and efficacy were analyzed as well as the management of supplementation with pyridoxine or pyridoxal-5I-phosphate both in the acute phases and in the maintenance therapies. The authors also analyzed alternative therapeutic strategies for ALDH7A1 deficiency (lysine-restricted diet, arginine supplementation, oligonucleotide antisense therapy, upstream inhibition of aminoadipic semialdehyde synthase). Expert opinion: The administration of pyridoxine or pyridoxal-5I-phosphate should be considered in all intractable seizures also beyond the first year of life. Lysine restricted diet and arginine supplementation should be introduced in all the confirmed ALDH7A1 deficient patients. Pre or post-natal supplementation with pyridoxine should be given in familial cases until an eventual molecular genetic disconfirmation. Minor data about alternative therapies are available for other disorders of vitamin B6 metabolism.
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Affiliation(s)
- Mario Mastrangelo
- Division of Child Neurology and Infantile Psychiatry, Department of Human Neurosciences, Sapienza University of Rome , Roma , Italy
| | - Serena Cesario
- Division of Child Neurology and Infantile Psychiatry, Department of Human Neurosciences, Sapienza University of Rome , Roma , Italy
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Ochoa JH, Sosa-Olavarria A, Quiroga H, Sepulveda W. Sonographic Detection of Seizure-Like Activity in Fetuses with Congenital Infection: Report of Three Cases and Review of the Literature. Fetal Diagn Ther 2019; 46:207-216. [PMID: 31352447 DOI: 10.1159/000500023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/27/2019] [Indexed: 11/19/2022]
Abstract
Fetal seizure is a very rare prenatal finding and associated with an almost invariably poor outcome, the most common causes being hypoxic-ischemic encephalopathy, congenital anomalies of either the central nervous system (CNS) or musculoskeletal system, and metabolic disorders. The prenatal detection of seizure-like activity in fetuses with congenital infection has not been previously reported. In this report, we describe 3 cases of seizures in fetuses with congenital infection including Zika virus (n = 2) and toxoplasmosis (n = 1). All 3 fetuses had associated CNS abnormalities and the perinatal outcome was uniformly poor. This report suggests that for fetuses with proven congenital infections an extended and targeted sonographic examination may be helpful in -detecting associated fetal seizures that may even worsen the neonatal outcome.
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Affiliation(s)
| | | | | | - Waldo Sepulveda
- FETALMED, Maternal-Fetal Diagnostic Center, Fetal Imaging Unit, Santiago, Chile
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67
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Wilson MP, Plecko B, Mills PB, Clayton PT. Disorders affecting vitamin B 6 metabolism. J Inherit Metab Dis 2019; 42:629-646. [PMID: 30671974 DOI: 10.1002/jimd.12060] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 12/12/2018] [Indexed: 12/21/2022]
Abstract
Vitamin B6 is present in our diet in many forms, however, only pyridoxal 5'-phosphate (PLP) can function as a cofactor for enzymes. The intestine absorbs nonphosphorylated B6 vitamers, which are converted by specific enzymes to the active PLP form. The role of PLP is enabled by its reactive aldehyde group. Pathways reliant on PLP include amino acid and neurotransmitter metabolism, folate and 1-carbon metabolism, protein and polyamine synthesis, carbohydrate and lipid metabolism, mitochondrial function and erythropoiesis. Besides the role of PLP as a cofactor B6 vitamers also play other cellular roles, for example, as antioxidants, modifying expression and action of steroid hormone receptors, affecting immune function, as chaperones and as an antagonist of Adenosine-5'-triphosphate (ATP) at P2 purinoceptors. Because of the vital role of PLP in neurotransmitter metabolism, particularly synthesis of the inhibitory transmitter γ-aminobutyric acid, it is not surprising that various inborn errors leading to PLP deficiency manifest as B6 -responsive epilepsy, usually of early onset. This includes pyridox(am)ine phosphate oxidase deficiency (a disorder affecting PLP synthesis and recycling), disorders affecting PLP import into the brain (hypophosphatasia and glycosylphosphatidylinositol anchor synthesis defects), a disorder of an intracellular PLP-binding protein (PLPBP, previously named PROSC) and disorders where metabolites accumulate that inactivate PLP, for example, ALDH7A1 deficiency and hyperprolinaemia type II. Patients with these disorders can show rapid control of seizures in response to either pyridoxine and/or PLP with a lifelong dependency on supraphysiological vitamin B6 supply. The clinical and biochemical features of disorders leading to B6 -responsive seizures and the treatment of these disorders are described in this review.
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Affiliation(s)
- Matthew P Wilson
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health, London, UK
| | - Barbara Plecko
- Department of Pediatrics and Adolescent Medicine, Division of General Pediatrics, University Childrens' Hospital Graz, Medical University Graz, Graz, Austria
| | - Philippa B Mills
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health, London, UK
| | - Peter T Clayton
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health, London, UK
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Kernohan KD, Hartley T, Naumenko S, Armour CM, Graham GE, Nikkel SM, Lines M, Geraghty MT, Richer J, Mears W, Boycott KM, Dyment DA. Diagnostic clarity of exome sequencing following negative comprehensive panel testing in the neonatal intensive care unit. Am J Med Genet A 2019; 176:1688-1691. [PMID: 30160830 DOI: 10.1002/ajmg.a.38838] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 04/25/2018] [Accepted: 04/26/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Kristin D Kernohan
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Taila Hartley
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Sergey Naumenko
- Centre for Computational Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Christine M Armour
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Gail E Graham
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada
| | - Sarah M Nikkel
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Matthew Lines
- Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada
| | - Michael T Geraghty
- Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada
| | - Julie Richer
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada
| | - Wendy Mears
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Kym M Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.,Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada
| | - David A Dyment
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Ontario, Canada.,Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.,Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada
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69
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Conserved Pyridoxal 5'-Phosphate-Binding Protein YggS Impacts Amino Acid Metabolism through Pyridoxine 5'-Phosphate in Escherichia coli. Appl Environ Microbiol 2019; 85:AEM.00430-19. [PMID: 30902856 DOI: 10.1128/aem.00430-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 03/15/2019] [Indexed: 12/31/2022] Open
Abstract
Escherichia coli YggS (COG0325) is a member of the highly conserved pyridoxal 5'-phosphate (PLP)-binding protein (PLPBP) family. Recent studies suggested a role for this protein family in the homeostasis of vitamin B6 and amino acids. The deletion or mutation of a member of this protein family causes pleiotropic effects in many organisms and is causative of vitamin B6-dependent epilepsy in humans. To date, little has been known about the mechanism by which lack of YggS results in these diverse phenotypes. In this study, we determined that the pyridoxine (PN) sensitivity observed in yggS-deficient E. coli was caused by the pyridoxine 5'-phosphate (PNP)-dependent overproduction of Val, which is toxic to E. coli The data suggest that the yggS mutation impacts Val accumulation by perturbing the biosynthetic of Thr from homoserine (Hse). Exogenous Hse inhibited the growth of the yggS mutant, caused further accumulation of PNP, and increased the levels of some intermediates in the Thr-Ile-Val metabolic pathways. Blocking the Thr biosynthetic pathway or decreasing the intracellular PNP levels abolished the perturbations of amino acid metabolism caused by the exogenous PN and Hse. Our data showed that a high concentration of intracellular PNP is the root cause of at least some of the pleiotropic phenotypes described for a yggS mutant of E. coli IMPORTANCE Recent studies showed that deletion or mutation of members of the YggS protein family causes pleiotropic effects in many organisms. Little is known about the causes, mechanisms, and consequences of these diverse phenotypes. It was previously shown that yggS mutations in E. coli result in the accumulation of PNP and some metabolites in the Ile/Val biosynthetic pathway. This work revealed that some exogenous stresses increase the aberrant accumulation of PNP in the yggS mutant. In addition, the current report provides evidence indicating that some, but not all, of the phenotypes of the yggS mutant in E. coli are due to the elevated PNP level. These results will contribute to continuing efforts to determine the molecular functions of the members of the YggS protein family.
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The Epilepsy Genetics Initiative: Systematic reanalysis of diagnostic exomes increases yield. Epilepsia 2019; 60:797-806. [PMID: 30951195 PMCID: PMC6519344 DOI: 10.1111/epi.14698] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 03/02/2019] [Accepted: 03/04/2019] [Indexed: 12/15/2022]
Abstract
OBJECTIVE The Epilepsy Genetics Initiative (EGI) was formed in 2014 to create a centrally managed database of clinically generated exome sequence data. EGI performs systematic research-based reanalysis to identify new molecular diagnoses that were not possible at the time of initial sequencing and to aid in novel gene discovery. Herein we report on the efficacy of this approach 3 years after inception. METHODS One hundred sixty-six individuals with epilepsy who underwent diagnostic whole exome sequencing (WES) were enrolled, including 139 who had not received a genetic diagnosis. Sequence data were transferred to the EGI and periodically reevaluated on a research basis. RESULTS Eight new diagnoses were made as a result of updated annotations or the discovery of novel epilepsy genes after the initial diagnostic analysis was performed. In five additional cases, we provided new evidence to support or contradict the likelihood of variant pathogenicity reported by the laboratory. One novel epilepsy gene was discovered through dual interrogation of research and clinically generated WES. SIGNIFICANCE EGI's diagnosis rate of 5.8% represents a considerable increase in diagnostic yield and demonstrates the value of periodic reinterrogation of whole exome data. The initiative's contributions to gene discovery underscore the importance of data sharing and the value of collaborative enterprises.
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71
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Johannsen J, Bierhals T, Deindl P, Hecher L, Hermann K, Hempel M, Kloth K, Denecke J. Excessive Seizure Clusters in an Otherwise Well-Controlled Epilepsy as a Possible Hallmark of Untreated Vitamin B6-Responsive Epilepsy due to a Homozygous PLPBP Missense Variant. J Pediatr Genet 2019; 8:222-225. [PMID: 31687261 DOI: 10.1055/s-0039-1685501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 03/11/2019] [Indexed: 01/14/2023]
Abstract
Recently, mutations in the PLPBP gene were described as a novel cause for vitamin B6-responsive epilepsy. We report the outcome in case of a male adolescent with a novel homozygous missense variant in PLPBP who was never treated with pyridoxine until the age of 16 years. He presented with only mild cognitive impairment and an early-onset, well-controlled epilepsy. In our patient, excessive seizure clusters and anxiety states occurred intermittently, suggesting that the combination might be a hallmark in untreated patients. Thus, mutations in PLPBP should be addressed even in adolescent patients with only mild learning disabilities and relatively good seizure control over the years.
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Affiliation(s)
- Jessika Johannsen
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tatjana Bierhals
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Philipp Deindl
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Laura Hecher
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Katharina Hermann
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maja Hempel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Katja Kloth
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jonas Denecke
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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72
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Coughlin CR, Swanson MA, Spector E, Meeks NJ, Kronquist KE, Aslamy M, Wempe MF, van Karnebeek CD, Gospe SM, Aziz VG, Tsai BP, Gao H, Nagy PL, Hyland K, van Dooren SJ, Salomons GS, Van Hove JL. The genotypic spectrum of ALDH7A1 mutations resulting in pyridoxine dependent epilepsy: A common epileptic encephalopathy. J Inherit Metab Dis 2019; 42:353-361. [PMID: 30043187 PMCID: PMC6345606 DOI: 10.1002/jimd.12045] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Pyridoxine dependent epilepsy (PDE) is a treatable epileptic encephalopathy characterized by a positive response to pharmacologic doses of pyridoxine. Despite seizure control, at least 75% of individuals have intellectual disability and developmental delay. Current treatment paradigms have resulted in improved cognitive outcomes emphasizing the importance of an early diagnosis. As genetic testing is increasingly accepted as first tier testing for epileptic encephalopathies, we aimed to provide a comprehensive overview of ALDH7A1 mutations that cause PDE. The genotypes, ethnic origin and reported gender was collected from 185 subjects with a diagnosis of PDE. The population frequency for the variants in this report and the existing literature were reviewed in the Genome Aggregation Database (gnomAD). Novel variants identified in population databases were also evaluated through in silico prediction software and select variants were over-expressed in an E.coli-based expression system to measure α-aminoadipic semialdehyde dehydrogenase activity and production of α-aminoadipic acid. This study adds 47 novel variants to the literature resulting in a total of 165 reported pathogenic variants. Based on this report, in silico predictions, and general population data, we estimate an incidence of approximately 1:64,352 live births. This report provides a comprehensive overview of known ALDH7A1 mutations that cause PDE, and suggests that PDE may be more common than initially estimated. Due to the relative high frequency of the disease, the likelihood of under-diagnosis given the wide clinical spectrum and limited awareness among clinicians as well as the cognitive improvement noted with early treatment, newborn screening for PDE may be warranted.
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Affiliation(s)
- Curtis R. Coughlin
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
- These authors contributed equally to the manuscript
- Correspondence: Curtis Coughlin II,
| | - Michael A. Swanson
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
- These authors contributed equally to the manuscript
| | - Elaine Spector
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
- Molecular Genetics Laboratory, Department of Pathology and Laboratory Medicine, Children’s Hospital Colorado, Aurora, CO 80045, USA
| | - Naomi J.L. Meeks
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
- Molecular Genetics Laboratory, Department of Pathology and Laboratory Medicine, Children’s Hospital Colorado, Aurora, CO 80045, USA
| | - Kathryn E. Kronquist
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
- Molecular Genetics Laboratory, Department of Pathology and Laboratory Medicine, Children’s Hospital Colorado, Aurora, CO 80045, USA
| | - Mezhgan Aslamy
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Michael F. Wempe
- School of Pharmacy, Department of Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Clara D.M. van Karnebeek
- Department of Pediatrics and Clinical Genetics, Academic Medical Centre, 1105 AZ Amsterdam, The Netherlands
- Department of Pediatrics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver BC V5Z4H4, Canada
| | - Sidney M. Gospe
- Division of Pediatric Neurology, Departments of Neurology and Pediatrics, University of Washington, Seattle, WA, USA
- Seattle Children’s Research Institute, Seattle, WA, USA
| | | | | | - Hanlin Gao
- Fulgent Genetics, Temple City, CA, 91780, USA
| | - Peter L. Nagy
- Medical Neurogenetics Laboratories, LLC, Atlanta, GA, USA
| | - Keith Hyland
- Medical Neurogenetics Laboratories, LLC, Atlanta, GA, USA
| | - Silvy J.M. van Dooren
- Department of Clinical Chemistry, Metabolic Unit, VU University Medical Center & Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Gajja S. Salomons
- Department of Clinical Chemistry, Metabolic Unit, VU University Medical Center & Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Johan L.K. Van Hove
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
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73
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Møller RS, Hammer TB, Rubboli G, Lemke JR, Johannesen KM. From next-generation sequencing to targeted treatment of non-acquired epilepsies. Expert Rev Mol Diagn 2019; 19:217-228. [DOI: 10.1080/14737159.2019.1573144] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Rikke S. Møller
- Department of Epilepsy Genetics and Precision Medicine, The Danish Epilepsy Centre, Dianalund, Denmark
- Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Trine B. Hammer
- Department of Epilepsy Genetics and Precision Medicine, The Danish Epilepsy Centre, Dianalund, Denmark
| | - Guido Rubboli
- Department of Epilepsy Genetics and Precision Medicine, The Danish Epilepsy Centre, Dianalund, Denmark
- Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Johannes R. Lemke
- Institute of Human Genetics, University of Leipzig Hospitals and Clinics, Leipzig, Germany
| | - Katrine M. Johannesen
- Department of Epilepsy Genetics and Precision Medicine, The Danish Epilepsy Centre, Dianalund, Denmark
- Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
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Abstract
Inborn errors of metabolism, also known as inherited metabolic diseases, constitute an important group of conditions presenting with neurologic signs in newborns. They are individually rare but collectively common. Many are treatable through restoration of homeostasis of a disrupted metabolic pathway. Given their frequency and potential for treatment, the clinician should be aware of this group of conditions and learn to identify the typical manifestations of the different inborn errors of metabolism. In this review, we summarize the clinical, laboratory, electrophysiologic, and neuroimaging findings of the different inborn errors of metabolism that can present with florid neurologic signs and symptoms in the neonatal period.
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MESH Headings
- Adult
- Female
- Humans
- Infant, Newborn
- Infant, Newborn, Diseases/diagnosis
- Infant, Newborn, Diseases/diagnostic imaging
- Infant, Newborn, Diseases/physiopathology
- Infant, Newborn, Diseases/therapy
- Metabolism, Inborn Errors/diagnosis
- Metabolism, Inborn Errors/diagnostic imaging
- Metabolism, Inborn Errors/physiopathology
- Metabolism, Inborn Errors/therapy
- Neuroimaging
- Pregnancy
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Affiliation(s)
- Carlos R Ferreira
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, United States; Rare Disease Institute, Children's National Health System, Washington, DC, United States
| | - Clara D M van Karnebeek
- Departments of Pediatrics and Clinical Genetics, Amsterdam University Medical Centers, Amsterdam, The Netherlands; Department of Pediatrics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada.
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75
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Improved cognition, mild anxiety-like behavior and decreased motor performance in pyridoxal phosphatase-deficient mice. Biochim Biophys Acta Mol Basis Dis 2019; 1865:193-205. [DOI: 10.1016/j.bbadis.2018.08.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 08/13/2018] [Accepted: 08/14/2018] [Indexed: 01/02/2023]
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76
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Hassel B, Rogne AG, Hope S. Intellectual Disability Associated With Pyridoxine-Responsive Epilepsies: The Need to Protect Cognitive Development. Front Psychiatry 2019; 10:116. [PMID: 30930802 PMCID: PMC6423912 DOI: 10.3389/fpsyt.2019.00116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 02/15/2019] [Indexed: 01/03/2023] Open
Abstract
Pyridoxine (vitamin B6)-responsive epilepsies are severe forms of epilepsy that manifest as seizures immediately after birth, sometimes in utero, sometimes months, or years after birth. Seizures may be treated efficiently by life-long supplementation with pyridoxine or its biologically active form, pyridoxal phosphate, but even so patients may become intellectually disabled, for which there currently is no effective treatment. The condition may be caused by mutations in several genes (TNSALP, PIGV, PIGL, PIGO, PNPO, PROSC, ALDH7A1, MOCS2, or ALDH4A1). Mutations in ALDH7A1, MOCS2, and ALDH4A1 entail build-up of reactive aldehydes (α-aminoadipic semialdehyde, γ-glutamic semialdehyde) that may react non-enzymatically with macromolecules of brain cells. Such reactions may alter the function of macromolecules, and they may produce "advanced glycation end products" (AGEs). AGEs trigger inflammation in the brain. This understanding points to aldehyde-quenching, anti-AGE, or anti-inflammatory therapies as possible strategies to protect cognitive development and prevent intellectual disability in affected children. Studies on how aldehydes traverse cell membranes and how they affect brain function could further the development of therapies for patients with pyridoxine-responsive epilepsies.
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Affiliation(s)
- Bjørnar Hassel
- Department for Neurohabilitation, Oslo University Hospital and University of Oslo, Oslo, Norway.,Norwegian Defence Research Establishment (FFI), Kjeller, Norway
| | - Ane Gretesdatter Rogne
- Department for Neurohabilitation, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Sigrun Hope
- Department for Neurohabilitation, Oslo University Hospital and University of Oslo, Oslo, Norway
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77
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van Karnebeek CDM, Sayson B, Lee JJY, Tseng LA, Blau N, Horvath GA, Ferreira CR. Metabolic Evaluation of Epilepsy: A Diagnostic Algorithm With Focus on Treatable Conditions. Front Neurol 2018; 9:1016. [PMID: 30559706 PMCID: PMC6286965 DOI: 10.3389/fneur.2018.01016] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 11/12/2018] [Indexed: 01/04/2023] Open
Abstract
Although inborn errors of metabolism do not represent the most common cause of seizures, their early identification is of utmost importance, since many will require therapeutic measures beyond that of common anti-epileptic drugs, either in order to control seizures, or to decrease the risk of neurodegeneration. We translate the currently-known literature on metabolic etiologies of epilepsy (268 inborn errors of metabolism belonging to 21 categories, with 74 treatable errors), into a 2-tiered diagnostic algorithm, with the first-tier comprising accessible, affordable, and less invasive screening tests in urine and blood, with the potential to identify the majority of treatable conditions, while the second-tier tests are ordered based on individual clinical signs and symptoms. This resource aims to support the pediatrician, neurologist, biochemical, and clinical geneticists in early identification of treatable inborn errors of metabolism in a child with seizures, allowing for timely initiation of targeted therapy with the potential to improve outcomes.
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Affiliation(s)
- Clara D M van Karnebeek
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada.,Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, BC, Canada.,Departments of Pediatrics and Clinical Genetics, Emma Children's Hospital, Amsterdam University Medical Centres, Amsterdam, Netherlands
| | - Bryan Sayson
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - Jessica J Y Lee
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - Laura A Tseng
- Departments of Pediatrics and Clinical Genetics, Emma Children's Hospital, Amsterdam University Medical Centres, Amsterdam, Netherlands
| | - Nenad Blau
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Heidelberg, Germany.,Division of Metabolism, University Children's Hospital, Zurich, Switzerland
| | - Gabriella A Horvath
- Division of Biochemical Diseases, Department of Pediatrics, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - Carlos R Ferreira
- Division of Genetics and Metabolism, Children's National Health System, Washington, DC, United States.,National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, United States
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Tumienė B, Peterlin B, Maver A, Utkus A. Contemporary scope of inborn errors of metabolism involving epilepsy or seizures. Metab Brain Dis 2018; 33:1781-1786. [PMID: 30006695 DOI: 10.1007/s11011-018-0288-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 07/10/2018] [Indexed: 01/15/2023]
Abstract
Many inborn errors of metabolism may present with epilepsy or seizures, however, current scope of these diseases is unknown. Due to available precision medicine approaches in many inborn errors of metabolism and sophisticated traditional diagnostics, this group of disorders is of special relevance to clinicians. Besides, as current treatment is challenging and unsuccessful in more than 30% of all epilepsy patients, these diseases may provide valuable models for ictogenesis and epileptogenesis studies and potentially pave the ways to identification of novel treatments. The aim of this study was to elucidate genetic architecture of inborn errors of metabolism involving epilepsy or seizures and to evaluate their diagnostic approaches. After extensive search, 880 human genes were identified with a considerable part, 373 genes (42%), associated with inborn errors of metabolism. The most numerous group comprised disorders of energy metabolism (115, 31% of all inborn errors of metabolism). A substantial number of these diseases (26%, 97/373) have established specific treatments, therefore timely diagnosis comes as an obligation. Highly heterogenous, overlapping and non-specific phenotypes in most of inborn errors of metabolism presenting with epilepsy or seizures usually preclude phenotype-driven diagnostics. Besides, as traditional diagnostics involves a range of specialized metabolic tests with low diagnostic yields and is generally inefficient and lengthy, next-generation sequencing-based methods were proposed as a cost-efficient one-step way to shorten "diagnostic odyssey". Extensive list of 373 epilepsy- or seizures-associated inborn errors of metabolism genes may be of value in development of gene panels and as a tool for variants' filtration.
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Affiliation(s)
- Birutė Tumienė
- Institute of Biomedical Sciences, Faculty of Medicine, Vilnius University, Santariskiu 2, LT-08661, Vilnius, Lithuania.
- Vilnius University Hospital Santaros Klinikos, Santariskiu 2, LT-08661, Vilnius, Lithuania.
| | - Borut Peterlin
- Clinical Institute for Medical Genetics, Division of Gynecology, University of Ljubljana Medical Centre, Ljubljana, Slovenia
| | - Aleš Maver
- Clinical Institute for Medical Genetics, Division of Gynecology, University of Ljubljana Medical Centre, Ljubljana, Slovenia
| | - Algirdas Utkus
- Institute of Biomedical Sciences, Faculty of Medicine, Vilnius University, Santariskiu 2, LT-08661, Vilnius, Lithuania
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Forcada-Nadal A, Llácer JL, Contreras A, Marco-Marín C, Rubio V. The P II-NAGK-PipX-NtcA Regulatory Axis of Cyanobacteria: A Tale of Changing Partners, Allosteric Effectors and Non-covalent Interactions. Front Mol Biosci 2018; 5:91. [PMID: 30483512 PMCID: PMC6243067 DOI: 10.3389/fmolb.2018.00091] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 10/18/2018] [Indexed: 11/13/2022] Open
Abstract
PII, a homotrimeric very ancient and highly widespread (bacteria, archaea, plants) key sensor-transducer protein, conveys signals of abundance or poorness of carbon, energy and usable nitrogen, converting these signals into changes in the activities of channels, enzymes, or of gene expression. PII sensing is mediated by the PII allosteric effectors ATP, ADP (and, in some organisms, AMP), 2-oxoglutarate (2OG; it reflects carbon abundance and nitrogen scarcity) and, in many plants, L-glutamine. Cyanobacteria have been crucial for clarification of the structural bases of PII function and regulation. They are the subject of this review because the information gathered on them provides an overall structure-based view of a PII regulatory network. Studies on these organisms yielded a first structure of a PII complex with an enzyme, (N-acetyl-Lglutamate kinase, NAGK), deciphering how PII can cause enzyme activation, and how it promotes nitrogen stockpiling as arginine in cyanobacteria and plants. They have also revealed the first clear-cut mechanism by which PII can control gene expression. A small adaptor protein, PipX, is sequestered by PII when nitrogen is abundant and is released when is scarce, swapping partner by binding to the 2OG-activated transcriptional regulator NtcA, co-activating it. The structures of PII-NAGK, PII-PipX, PipX alone, of NtcA in inactive and 2OG-activated forms and as NtcA-2OG-PipX complex, explain structurally PII regulatory functions and reveal the changing shapes and interactions of the T-loops of PII depending on the partner and on the allosteric effectors bound to PII. Cyanobacterial studies have also revealed that in the PII-PipX complex PipX binds an additional transcriptional factor, PlmA, thus possibly expanding PipX roles beyond NtcA-dependency. Further exploration of these roles has revealed a functional interaction of PipX with PipY, a pyridoxal-phosphate (PLP) protein involved in PLP homeostasis whose mutations in the human ortholog cause epilepsy. Knowledge of cellular levels of the different components of this PII-PipX regulatory network and of KD values for some of the complexes provides the basic background for gross modeling of the system at high and low nitrogen abundance. The cyanobacterial network can guide searches for analogous components in other organisms, particularly of PipX functional analogs.
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Affiliation(s)
- Alicia Forcada-Nadal
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas, Valencia, Spain.,Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain
| | - José Luis Llácer
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas, Valencia, Spain.,Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras - Instituto de Salud Carlos III, Valencia, Spain
| | - Asunción Contreras
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain
| | - Clara Marco-Marín
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas, Valencia, Spain.,Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras - Instituto de Salud Carlos III, Valencia, Spain
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas, Valencia, Spain.,Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras - Instituto de Salud Carlos III, Valencia, Spain
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80
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Shiraku H, Nakashima M, Takeshita S, Khoo CS, Haniffa M, Ch'ng GS, Takada K, Nakajima K, Ohta M, Okanishi T, Kanai S, Fujimoto A, Saitsu H, Matsumoto N, Kato M. PLPBP mutations cause variable phenotypes of developmental and epileptic encephalopathy. Epilepsia Open 2018; 3:495-502. [PMID: 30525118 PMCID: PMC6276781 DOI: 10.1002/epi4.12272] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2018] [Indexed: 11/06/2022] Open
Abstract
Objective Vitamin B6-dependent epilepsies are treatable disorders caused by variants in several genes, such as ALDH7A1,PNPO, and others. Recently, biallelic variants in PLPBP, formerly known as PROSC, were identified as a novel cause of vitamin B6-dependent epilepsies. Our objective was to further delineate the phenotype of PLPBP mutation. Methods We identified 4 unrelated patients harboring a total of 4 variants in PLPBP, including 3 novel variants, in a cohort of 700 patients with developmental and epileptic encephalopathies. Clinical information in each case was collected. Results Each patient had a different clinical course of epilepsy, with seizure onset from the first day of life to 3 months of age. Generalized tonic-clonic seizures were commonly noted. Myoclonic seizures or focal seizures were also observed in 2 patients. Interictal electroencephalography showed variable findings, such as suppression burst, focal or multifocal discharges, and diffuse slow activity. Unlike previous reports, all the patients had some degree of intellectual disability, although some of them had received early treatment with vitamin B6, suggesting that different mutation types influence the severity and outcome of the seizures. Significance PLPBP variants should be regarded as among the causative genes of developmental and epileptic encephalopathy, even when it occurs after the neonatal period. Early diagnosis and proper treatment with pyridoxine or pyridoxal phosphate is essential to improve the neurologic prognosis in neonates or young children with poorly controlled seizures.
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Affiliation(s)
- Hiroshi Shiraku
- Department of Pediatrics JA Toride General Hospital Toride Japan.,Department of Child Neurology National Center of Neurology and Psychiatry Kodaira, Tokyo Japan
| | - Mitsuko Nakashima
- Department of Human Genetics Yokohama City University Graduate School of Medicine Yokohama Japan.,Department of Biochemistry Hamamatsu University School of Medicine Hamamatsu Japan
| | - Saoko Takeshita
- Department of Pediatrics Yokohama City University Medical Center Yokohama Japan
| | - Chai-Soon Khoo
- Department of Paediatrics Sarawak General Hospital Kuching Malaysia
| | - Muzhirah Haniffa
- Department of Genetics Hospital Kuala Lumpur Kuala Lumpur Malaysia
| | - Gaik-Siew Ch'ng
- Department of Genetics Hospital Kuala Lumpur Kuala Lumpur Malaysia
| | - Kazuma Takada
- Department of Pediatrics JA Toride General Hospital Toride Japan
| | - Keisuke Nakajima
- Department of Pediatrics JA Toride General Hospital Toride Japan
| | - Masayasu Ohta
- Department of Pediatrics JA Toride General Hospital Toride Japan
| | - Tohru Okanishi
- Department of Child Neurology Comprehensive Epilepsy Center Seirei-Hamamatsu General Hospital Shizuoka Japan
| | - Sotaro Kanai
- Department of Child Neurology Comprehensive Epilepsy Center Seirei-Hamamatsu General Hospital Shizuoka Japan
| | - Ayataka Fujimoto
- Department of Neurosurgery Comprehensive Epilepsy Center Seirei-Hamamatsu General Hospital Hamamatsu Japan
| | - Hirotomo Saitsu
- Department of Biochemistry Hamamatsu University School of Medicine Hamamatsu Japan
| | - Naomichi Matsumoto
- Department of Human Genetics Yokohama City University Graduate School of Medicine Yokohama Japan
| | - Mitsuhiro Kato
- Department of Pediatrics Showa University School of Medicine Shinagawa-ku, Tokyo Japan
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81
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Toldo I, Bonardi CM, Bettella E, Polli R, Talenti G, Burlina A, Sartori S, Murgia A. Brain malformations associated to Aldh7a1 gene mutations: Report of a novel homozygous mutation and literature review. Eur J Paediatr Neurol 2018; 22:1042-1053. [PMID: 30005813 DOI: 10.1016/j.ejpn.2018.06.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 06/20/2018] [Accepted: 06/27/2018] [Indexed: 01/27/2023]
Abstract
BACKGROUND The ALDH7A1 gene is known to be responsible for autosomal recessive pyridoxine-dependent epilepsy (OMIM 266100). The phenotypic spectrum of ALDH7A1 mutations is very heterogeneous ranging from refractory epilepsy and neurodevelopmental delay, to multisystem neonatal disorder. AIM The present study aims at describing the phenotype associated with a novel homozygous ALDH7A1 mutation and the spectrum of brain malformations associated with pyridoxine-dependent epilepsy. METHODS We conducted a literature review on the Internet database Pubmed (up to November 2017) searching for ALDH7A1 mutations associated with brain malformations and brain MRI findings. RESULTS We present the case of two siblings, children of related parents. The proband presented neonatal focal seizures not responding to conventional antiepileptic drugs. Electroencephalography showed a suppression burst pattern and several multifocal ictal patterns, responsive to pyridoxine. Brain MRI was normal. Molecular analysis by targeted next-generation sequencing panel for epileptic encephalopathy disclosed a homozygous missense mutation of ALDH7A1. The same mutation was then found in a stored sample of DNA from peripheral blood of an older sister dead 3 years earlier. This girl presented a complex brain malformation diagnosed with a foetal MRI and had neonatal refractory seizures with suppression burst pattern. She died at 6 months of age. LITERATURE REVIEW The brain abnormalities most frequently reported in pyridoxine-dependent epilepsy include: agenesia/hypoplasia of the corpus callosum, not specific white matter abnormalities, large cisterna magna, ventriculomegaly, haemorrhages, cerebellum hypoplasia/dysplasia, and, more rarely, dysplasia of the brainstem and hydrocephalus. DISCUSSION AND CONCLUSIONS ALDH7A1 mutations have been associated to different brain abnormalities, documented by MRI only in few cases. The study cases expand the clinical spectrum of ALDH7A1 associated conditions, suggesting to look for ALDH7A1 mutations not only in classical phenotypes but also in patients with brain malformations, mainly if there is a response to a pyridoxine trial.
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Affiliation(s)
- Irene Toldo
- Department of Woman's and Child's Health, University Hospital of Padua, Italy.
| | | | - Elisa Bettella
- Department of Woman's and Child's Health, University Hospital of Padua, Italy.
| | - Roberta Polli
- Department of Woman's and Child's Health, University Hospital of Padua, Italy.
| | - Giacomo Talenti
- Department of Neurosciences, University Hospital of Padua, Italy.
| | - Alberto Burlina
- Department of Woman's and Child's Health, University Hospital of Padua, Italy.
| | - Stefano Sartori
- Department of Woman's and Child's Health, University Hospital of Padua, Italy.
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82
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Myers KA, Johnstone DL, Dyment DA. Epilepsy genetics: Current knowledge, applications, and future directions. Clin Genet 2018; 95:95-111. [PMID: 29992546 DOI: 10.1111/cge.13414] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 07/03/2018] [Accepted: 07/06/2018] [Indexed: 12/12/2022]
Abstract
The rapid pace of disease gene discovery has resulted in tremendous advances in the field of epilepsy genetics. Clinical testing with comprehensive gene panels, exomes, and genomes are now available and have led to higher diagnostic rates and insights into the underlying disease processes. As such, the contribution to the care of patients by medical geneticists, neurogeneticists and genetic counselors are significant; the dysmorphic examination, the necessary pre- and post-test counseling, the selection of the appropriate next-generation sequencing-based test(s), and the interpretation of sequencing results require a care provider to have a comprehensive working knowledge of the strengths and limitations of the available testing technologies. As the underlying mechanisms of the encephalopathies and epilepsies are better understood, there may be opportunities for the development of novel therapies based on an individual's own specific genotype. Drug screening with in vitro and in vivo models of epilepsy can potentially facilitate new treatment strategies. The future of epilepsy genetics will also probably include other-omic approaches such as transcriptomes, metabolomes, and the expanded use of whole genome sequencing to further improve our understanding of epilepsy and provide better care for those with the disease.
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Affiliation(s)
- K A Myers
- Department of Pediatrics, University of McGill, Montreal, Canada.,Research Institute of the McGill University Health Centre, Montreal, Canada
| | - D L Johnstone
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
| | - D A Dyment
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada.,Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Canada
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83
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Tremiño L, Forcada-Nadal A, Rubio V. Insight into vitamin B 6 -dependent epilepsy due to PLPBP (previously PROSC) missense mutations. Hum Mutat 2018; 39:1002-1013. [PMID: 29689137 DOI: 10.1002/humu.23540] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/03/2018] [Accepted: 04/20/2018] [Indexed: 11/11/2022]
Abstract
Vitamin B6 -dependent genetic epilepsy was recently associated to mutations in PLPBP (previously PROSC), the human version of the widespread COG0325 gene that encodes TIM-barrel-like pyridoxal phosphate (PLP)-containing proteins of unclear function. We produced recombinantly, purified and characterized human PROSC (called now PLPHP) and its six missense mutants reported in epileptic patients. Normal PLPHP is largely a monomer with PLP bound through a Schiff-base linkage. The PLP-targeting antibiotic d-cycloserine decreased the PLP-bound peak as expected for pseudo-first-order reaction. The p.Leu175Pro mutation grossly misfolded PLPHP. Mutations p.Arg241Gln and p.Pro87Leu decreased protein solubility and yield of pure PLPHP, but their pure forms were well folded, similarly to pure p.Pro40Leu, p.Tyr69Cys, and p.Arg205Gln mutants (judged from CD spectra). PLPHP stability was decreased in p.Arg241Gln, p.Pro40Leu, and p.Arg205Gln mutants (thermofluor assays). The p.Arg241Gln and p.Tyr69Cys mutants respectively lacked PLP or had a decreased amount of this cofactor. With p.Tyr69Cys there was extensive protein dimerization due to disulfide bridge formation, and PLP accessibility was decreased (judged from d-cycloserine reaction). A 3-D model of human PLPHP allowed rationalizing the effects of most mutations. Overall, the six missense mutations caused ill effects and five of them impaired folding or decreased stability, suggesting the potential of pharmacochaperone-based therapeutic approaches.
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Affiliation(s)
- Lorena Tremiño
- Instituto de Biomedicina de Valencia (IBV-CSIC), Valencia, Spain
| | | | - Vicente Rubio
- Instituto de Biomedicina de Valencia (IBV-CSIC), Valencia, Spain.,Group 739 of the Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
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84
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Evidence that the metabolite repair enzyme NAD(P)HX epimerase has a moonlighting function. Biosci Rep 2018; 38:BSR20180223. [PMID: 29654173 PMCID: PMC5938422 DOI: 10.1042/bsr20180223] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/04/2018] [Accepted: 04/09/2018] [Indexed: 11/25/2022] Open
Abstract
NAD(P)H-hydrate epimerase (EC 5.1.99.6) is known to help repair NAD(P)H hydrates (NAD(P)HX), which are damage products existing as R and S epimers. The S epimer is reconverted to NAD(P)H by a dehydratase; the epimerase facilitates epimer interconversion. Epimerase deficiency in humans causes a lethal disorder attributed to NADHX accumulation. However, bioinformatic evidence suggest caution about this attribution by predicting that the epimerase has a second function connected to vitamin B6 (pyridoxal 5′-phosphate and related compounds). Specifically, (i) the epimerase is fused to a B6 salvage enzyme in plants, (ii) epimerase genes cluster on the chromosome with B6-related genes in bacteria, and (iii) epimerase and B6-related genes are coexpressed in yeast and Arabidopsis. The predicted second function was explored in Escherichia coli, whose epimerase and dehydratase are fused and encoded by yjeF. The putative NAD(P)HX epimerase active site has a conserved lysine residue (K192 in E. coli YjeF). Changing this residue to alanine cut in vitro epimerase activity by ≥95% but did not affect dehydratase activity. Mutant cells carrying the K192A mutation had essentially normal NAD(P)HX dehydratase activity and NAD(P)HX levels, showing that the mutation had little impact on NAD(P)HX repair in vivo. However, these cells showed metabolome changes, particularly in amino acids, which exceeded those in cells lacking the entire yjeF gene. The K192A mutant cells also had reduced levels of ‘free’ (i.e. weakly bound or unbound) pyridoxal 5'-phosphate. These results provide circumstantial evidence that the epimerase has a metabolic function beyond NAD(P)HX repair and that this function involves vitamin B6.
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85
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Genetics of Epilepsy in the Era of Precision Medicine: Implications for Testing, Treatment, and Genetic Counseling. CURRENT GENETIC MEDICINE REPORTS 2018. [DOI: 10.1007/s40142-018-0139-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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86
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Falsaperla R, Vari MS, Toldo I, Murgia A, Sartori S, Vecchi M, Suppiej A, Burlina A, Mastrangelo M, Leuzzi V, Marchiani V, De Liso P, Capovilla G, Striano P, Vitaliti G. Pyridoxine-dependent epilepsies: an observational study on clinical, diagnostic, therapeutic and prognostic features in a pediatric cohort. Metab Brain Dis 2018; 33:261-269. [PMID: 29178011 DOI: 10.1007/s11011-017-0150-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 11/14/2017] [Indexed: 11/28/2022]
Abstract
The aim of our study was to describe the clinical, electroencephalogram, molecular findings and the diagnostic and therapeutic flow-chart of children with pyridoxine-dependent epilepsies (PDEs). We performed a retrospective observational study on children with PDEs, diagnosed and followed-up in Italian Pediatric Departments. In each centre, the authors collected data from a cohort of children admitted for intractable seizures, responsive to pyridoxine administration and resistant to other anticonvulsant therapies. Data were retrospectively analysed from January 2016 to January 2017. Sixteen patients (13 males, and 3 females) were included. We found that 93.75% of patients underwent conventional anticonvulsant therapy before starting pyridoxine administration and 62.5% had ex-juvantibus diagnosis, as specific serum diagnostic tests had been performed in only 37.5% of patients by alpha-AASA and pipecolic acid blood and urine dosage. The most common type of seizure was generalized tonic-clonic in 7 patients and the most common EEG pattern was characterized by a "burst suppression" pattern. Before pyridoxine administration, other anticonvulsant drugs were used in 93.75% of patients, with consequent onset of drug-resistance. Phenobarbital was the most frequently used drug as first-line treatment. The importance of our study relies on the need of a deeper knowledge of PDEs in terms of early diagnosis, avoiding incorrect treatment and related adverse events, clinical and EEG pathognomonic features, and genetic aspects of the disease.
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Affiliation(s)
- Raffaele Falsaperla
- General Pediatrics and Pediatric Acute and Emergency Unit, Policlinico-Vittorio-Emanuele University Hospital, University of Catania, Catania, Italy
| | - Maria Stella Vari
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, "G. Gaslini" Institute, Genoa, Italy
| | - Irene Toldo
- Neurology and Neurophysiology O.U., Department of Woman's and Child's Health, University Hospital of Padua, Padua, Italy
| | - Alessandra Murgia
- Neurology and Neurophysiology O.U., Department of Woman's and Child's Health, University Hospital of Padua, Padua, Italy
| | - Stefano Sartori
- Neurology and Neurophysiology O.U., Department of Woman's and Child's Health, University Hospital of Padua, Padua, Italy
| | - Marilena Vecchi
- Neurology and Neurophysiology O.U., Department of Woman's and Child's Health, University Hospital of Padua, Padua, Italy
| | - Agnese Suppiej
- Neurology and Neurophysiology O.U., Department of Woman's and Child's Health, University Hospital of Padua, Padua, Italy
| | - Alberto Burlina
- Inherited Metabolic Diseases O.U., Department of Woman's and Child's Health, University Hospital of Padua, Padua, Italy
| | - Mario Mastrangelo
- Department of Pediatrics, Child Neurology and Psychiatry, Sapienza University of Rome, Policlinico Umberto I Hospital, Rome, Italy
| | - Vincenzo Leuzzi
- Department of Pediatrics, Child Neurology and Psychiatry, Sapienza University of Rome, Policlinico Umberto I Hospital, Rome, Italy
| | - Valentina Marchiani
- Infantile Neuropsychiatry O.U., Policlinico Sant'Orsola-Malpighi, DIMEC, University of Bologna, Bologna, Italy
| | - Paola De Liso
- Department of Pediatrics, Child Neurology and Psychiatry, Sapienza University of Rome, Policlinico Umberto I Hospital, Rome, Italy
| | - Giuseppe Capovilla
- Department of Child Neuropsychiatry, Epilepsy Center, C. Poma Hospital, Mantua, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, "G. Gaslini" Institute, Genoa, Italy
| | - Giovanna Vitaliti
- General Pediatrics and Pediatric Acute and Emergency Unit, Policlinico-Vittorio-Emanuele University Hospital, University of Catania, Catania, Italy.
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87
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Clayton PT, Mills PB. Micronutrients. JOURNAL OF INBORN ERRORS OF METABOLISM AND SCREENING 2018. [DOI: 10.1177/2326409818765011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Peter T. Clayton
- Genetics and Genomic Medicine, UCL, Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Philippa B. Mills
- Genetics and Genomic Medicine, UCL, Great Ormond Street Institute of Child Health, London, United Kingdom
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88
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Pena IA, Roussel Y, Daniel K, Mongeon K, Johnstone D, Weinschutz Mendes H, Bosma M, Saxena V, Lepage N, Chakraborty P, Dyment DA, van Karnebeek CDM, Verhoeven-Duif N, Bui TV, Boycott KM, Ekker M, MacKenzie A. Pyridoxine-Dependent Epilepsy in Zebrafish Caused by Aldh7a1 Deficiency. Genetics 2017; 207:1501-1518. [PMID: 29061647 PMCID: PMC5714462 DOI: 10.1534/genetics.117.300137] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 10/04/2017] [Indexed: 11/25/2022] Open
Abstract
Pyridoxine-dependent epilepsy (PDE) is a rare disease characterized by mutations in the lysine degradation gene ALDH7A1 leading to recurrent neonatal seizures, which are uniquely alleviated by high doses of pyridoxine or pyridoxal 5'-phosphate (vitamin B6 vitamers). Despite treatment, neurodevelopmental disabilities are still observed in most PDE patients underlining the need for adjunct therapies. Over 60 years after the initial description of PDE, we report the first animal model for this disease: an aldh7a1-null zebrafish (Danio rerio) displaying deficient lysine metabolism and spontaneous and recurrent seizures in the larval stage (10 days postfertilization). Epileptiform electrographic activity was observed uniquely in mutants as a series of population bursts in tectal recordings. Remarkably, as is the case in human PDE, the seizures show an almost immediate sensitivity to pyridoxine and pyridoxal 5'-phosphate, with a resulting extension of the life span. Lysine supplementation aggravates the phenotype, inducing earlier seizure onset and death. By using mass spectrometry techniques, we further explored the metabolic effect of aldh7a1 knockout. Impaired lysine degradation with accumulation of PDE biomarkers, B6 deficiency, and low γ-aminobutyric acid levels were observed in the aldh7a1-/- larvae, which may play a significant role in the seizure phenotype and PDE pathogenesis. This novel model provides valuable insights into PDE pathophysiology; further research may offer new opportunities for drug discovery to control seizure activity and improve neurodevelopmental outcomes for PDE.
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Affiliation(s)
- Izabella A Pena
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Pediatrics, Faculty of Medicine, University of Ottawa, Ontario K1H 8L1, Canada
- Department of Biology, University of Ottawa, Ontario K1N 6N5, Canada
| | - Yann Roussel
- Department of Biology, University of Ottawa, Ontario K1N 6N5, Canada
| | - Kate Daniel
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
| | - Kevin Mongeon
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Pediatrics, Faculty of Medicine, University of Ottawa, Ontario K1H 8L1, Canada
| | - Devon Johnstone
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Pediatrics, Faculty of Medicine, University of Ottawa, Ontario K1H 8L1, Canada
| | | | - Marjolein Bosma
- Departments of Pediatrics and Clinical Genetics, Academic Medical Centre, 1105 AZ Amsterdam, The Netherlands
| | - Vishal Saxena
- Department of Biology, University of Ottawa, Ontario K1N 6N5, Canada
| | - Nathalie Lepage
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
| | - Pranesh Chakraborty
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
| | - David A Dyment
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Pediatrics, Faculty of Medicine, University of Ottawa, Ontario K1H 8L1, Canada
| | - Clara D M van Karnebeek
- Departments of Pediatrics and Clinical Genetics, Academic Medical Centre, 1105 AZ Amsterdam, The Netherlands
- Department of Pediatrics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver V5Z 4H4, British Columbia, Canada
| | - Nanda Verhoeven-Duif
- Department of Genetics, Center for Molecular Medicine, University Medical Center (UMC), 3584 EA Utrecht, The Netherlands
| | - Tuan Vu Bui
- Department of Biology, University of Ottawa, Ontario K1N 6N5, Canada
| | - Kym M Boycott
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Pediatrics, Faculty of Medicine, University of Ottawa, Ontario K1H 8L1, Canada
| | - Marc Ekker
- Department of Biology, University of Ottawa, Ontario K1N 6N5, Canada
| | - Alex MacKenzie
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Pediatrics, Faculty of Medicine, University of Ottawa, Ontario K1H 8L1, Canada
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89
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Ramos RJ, Pras-Raves ML, Gerrits J, van der Ham M, Willemsen M, Prinsen H, Burgering B, Jans JJ, Verhoeven-Duif NM. Vitamin B6 is essential for serine de novo biosynthesis. J Inherit Metab Dis 2017; 40:883-891. [PMID: 28801717 DOI: 10.1007/s10545-017-0061-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/29/2017] [Accepted: 05/31/2017] [Indexed: 11/30/2022]
Abstract
Pyridoxal 5'-phosphate (PLP), the metabolically active form of vitamin B6, plays an essential role in brain metabolism as a cofactor in numerous enzyme reactions. PLP deficiency in brain, either genetic or acquired, results in severe drug-resistant seizures that respond to vitamin B6 supplementation. The pathogenesis of vitamin B6 deficiency is largely unknown. To shed more light on the metabolic consequences of vitamin B6 deficiency in brain, we performed untargeted metabolomics in vitamin B6-deprived Neuro-2a cells. Significant alterations were observed in a range of metabolites. The most surprising observation was a decrease of serine and glycine, two amino acids that are known to be elevated in the plasma of vitamin B6 deficient patients. To investigate the cause of the low concentrations of serine and glycine, a metabolic flux analysis on serine biosynthesis was performed. The metabolic flux results showed that the de novo synthesis of serine was significantly reduced in vitamin B6-deprived cells. In addition, formation of glycine and 5-methyltetrahydrofolate was decreased. Thus, vitamin B6 is essential for serine de novo biosynthesis in neuronal cells, and serine de novo synthesis is critical to maintain intracellular serine and glycine. These findings suggest that serine and glycine concentrations in brain may be deficient in patients with vitamin B6 responsive epilepsy. The low intracellular 5-mTHF concentrations observed in vitro may explain the favourable but so far unexplained response of some patients with pyridoxine-dependent epilepsy to folinic acid supplementation.
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Affiliation(s)
- Rúben J Ramos
- Section Metabolic Diagnostics, Department of Genetics, University Medical Center Utrecht, KC02.069.1, Lundlaan 6, 3584 EA, Utrecht, The Netherlands
| | - Mia L Pras-Raves
- Section Metabolic Diagnostics, Department of Genetics, University Medical Center Utrecht, KC02.069.1, Lundlaan 6, 3584 EA, Utrecht, The Netherlands
| | - Johan Gerrits
- Section Metabolic Diagnostics, Department of Genetics, University Medical Center Utrecht, KC02.069.1, Lundlaan 6, 3584 EA, Utrecht, The Netherlands
| | - Maria van der Ham
- Section Metabolic Diagnostics, Department of Genetics, University Medical Center Utrecht, KC02.069.1, Lundlaan 6, 3584 EA, Utrecht, The Netherlands
| | - Marcel Willemsen
- Section Metabolic Diagnostics, Department of Genetics, University Medical Center Utrecht, KC02.069.1, Lundlaan 6, 3584 EA, Utrecht, The Netherlands
| | - Hubertus Prinsen
- Section Metabolic Diagnostics, Department of Genetics, University Medical Center Utrecht, KC02.069.1, Lundlaan 6, 3584 EA, Utrecht, The Netherlands
| | - Boudewijn Burgering
- Department of Molecular Cancer Research and Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, 3584 EA, The Netherlands
| | - Judith J Jans
- Section Metabolic Diagnostics, Department of Genetics, University Medical Center Utrecht, KC02.069.1, Lundlaan 6, 3584 EA, Utrecht, The Netherlands.
| | - Nanda M Verhoeven-Duif
- Section Metabolic Diagnostics, Department of Genetics, University Medical Center Utrecht, KC02.069.1, Lundlaan 6, 3584 EA, Utrecht, The Netherlands
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90
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Tremiño L, Forcada-Nadal A, Contreras A, Rubio V. Studies on cyanobacterial protein PipY shed light on structure, potential functions, and vitamin B 6 -dependent epilepsy. FEBS Lett 2017; 591:3431-3442. [PMID: 28914444 DOI: 10.1002/1873-3468.12841] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 08/21/2017] [Accepted: 09/01/2017] [Indexed: 11/11/2022]
Abstract
The Synechococcus elongatus COG0325 gene pipY functionally interacts with the nitrogen regulatory gene pipX. As a first step toward a molecular understanding of such interactions, we characterized PipY. This 221-residue protein is monomeric and hosts pyridoxal phosphate (PLP), binding it with limited affinity and losing it upon incubation with D-cycloserine. PipY crystal structures with and without PLP reveal a single-domain monomer folded as the TIM barrel of type-III fold PLP enzymes, with PLP highly exposed, fitting a role for PipY in PLP homeostasis. The mobile PLP phosphate-anchoring C-terminal helix might act as a trigger for PLP exchange. Exploiting the universality of COG0325 functions, we used PipY in site-directed mutagenesis studies to shed light on disease causation by epilepsy-associated mutations in the human COG0325 gene PROSC.
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Affiliation(s)
- Lorena Tremiño
- Instituto de Biomedicina de Valencia (IBV-CSIC), CIBER de Enfermedades Raras (CIBERER-ISCIII), Valencia, Spain
| | - Alicia Forcada-Nadal
- Instituto de Biomedicina de Valencia (IBV-CSIC), CIBER de Enfermedades Raras (CIBERER-ISCIII), Valencia, Spain.,Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Spain
| | - Asunción Contreras
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Spain
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia (IBV-CSIC), CIBER de Enfermedades Raras (CIBERER-ISCIII), Valencia, Spain
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91
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Wilson MP, Footitt EJ, Papandreou A, Uudelepp ML, Pressler R, Stevenson DC, Gabriel C, McSweeney M, Baggot M, Burke D, Stödberg T, Riney K, Schiff M, Heales SJR, Mills KA, Gissen P, Clayton PT, Mills PB. An LC-MS/MS-Based Method for the Quantification of Pyridox(am)ine 5'-Phosphate Oxidase Activity in Dried Blood Spots from Patients with Epilepsy. Anal Chem 2017; 89:8892-8900. [PMID: 28782931 PMCID: PMC5588098 DOI: 10.1021/acs.analchem.7b01358] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We report the development of a rapid, simple, and robust LC-MS/MS-based enzyme assay using dried blood spots (DBS) for the diagnosis of pyridox(am)ine 5'-phosphate oxidase (PNPO) deficiency (OMIM 610090). PNPO deficiency leads to potentially fatal early infantile epileptic encephalopathy, severe developmental delay, and other features of neurological dysfunction. However, upon prompt treatment with high doses of vitamin B6, affected patients can have a normal developmental outcome. Prognosis of these patients is therefore reliant upon a rapid diagnosis. PNPO activity was quantified by measuring pyridoxal 5'-phosphate (PLP) concentrations in a DBS before and after a 30 min incubation with pyridoxine 5'-phosphate (PNP). Samples from 18 PNPO deficient patients (1 day-25 years), 13 children with other seizure disorders receiving B6 supplementation (1 month-16 years), and 37 child hospital controls (5 days-15 years) were analyzed. DBS from the PNPO-deficient samples showed enzyme activity levels lower than all samples from these two other groups as well as seven adult controls; no false positives or negatives were identified. The method was fully validated and is suitable for translation into the clinical diagnostic arena.
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Affiliation(s)
- Matthew P Wilson
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health , 30 Guilford Street, London WC1N 1EH, United Kingdom
| | | | - Apostolos Papandreou
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health , 30 Guilford Street, London WC1N 1EH, United Kingdom
| | - Mari-Liis Uudelepp
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health , 30 Guilford Street, London WC1N 1EH, United Kingdom
| | | | | | | | | | | | | | - Tommy Stödberg
- Neuropediatric Unit, Karolinska University Hospital , Stockholm SE-171 76, Sweden
| | - Kate Riney
- Neurosciences Unit, The Lady Cilento Children's Hospital , 501 Stanley Street, South Brisbane, Queensland 4101, Australia
| | - Manuel Schiff
- Reference Center for Inborn Errors of Metabolism, Robert Debré University Hospital , APHP, Paris 75019, France
| | - Simon J R Heales
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health , 30 Guilford Street, London WC1N 1EH, United Kingdom.,Neurometabolic Unit, National Hospital for Neurology and Neurosurgery , Queen Square, London WC1N 3BG, United Kingdom
| | - Kevin A Mills
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health , 30 Guilford Street, London WC1N 1EH, United Kingdom
| | - Paul Gissen
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health , 30 Guilford Street, London WC1N 1EH, United Kingdom
| | - Peter T Clayton
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health , 30 Guilford Street, London WC1N 1EH, United Kingdom
| | - Philippa B Mills
- Genetics and Genomic Medicine, UCL GOS Institute of Child Health , 30 Guilford Street, London WC1N 1EH, United Kingdom
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92
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Falsaperla R, Corsello G. Pyridoxine dependent epilepsies: new therapeutical point of view. Ital J Pediatr 2017; 43:68. [PMID: 28779752 PMCID: PMC5545091 DOI: 10.1186/s13052-017-0387-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/28/2017] [Indexed: 12/01/2022] Open
Abstract
Pyridoxine dependent epilepsies (PDEs) are rare autosomal recessive disorders with onset in neonatal period. Seizures are typically not responsive to conventional antiepileptic drugs, but they cease after parental pyridoxine administration. Atypical forms are characterized partly response to pyridoxine and a late onset of symptoms (up to the age of three years). Prevalence is variable and it has rarely been described. The genes involved in PDEs are the gene encoding for the Alpha-aminoadipic-semialdehyde dehydrogenase (ALDH7A1) and PROSC gene, which encodes a pyridoxal-5-phosphate binding protein. Mutations in the gene encoding for the pyridoxal-5′-phosphate oxidase enzyme (PNPO) are responsible of a clinical entity similar to PDEs responsive to pyridoxal-5-phosphate administration not to pyridoxine administration. PDEs diagnosis is often delayed because they are suspected only after conventional anticonvulsant drugs resistance. Herein authors aim to present an expert point of view on PDEs in childhood, reviewing the most recent literature data and proposing a new therapeutical approach for seizures of unknown origin in all those children up to the age of three years.
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Affiliation(s)
- Raffaele Falsaperla
- Unit of Pediatrics and Pediatric Emergency, University Hospital "Policlinico-Vittorio Emanuele", Via Plebiscito 628, 95124, Catania, Italy.
| | - Giovanni Corsello
- Department of Maternal and Child Health, University of Palermo, Palermo, Italy
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93
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Akiyama T, Hayashi Y, Hanaoka Y, Shibata T, Akiyama M, Tsuchiya H, Yamaguchi T, Kobayashi K. Pyridoxal 5'-phosphate, pyridoxal, and 4-pyridoxic acid in the paired serum and cerebrospinal fluid of children. Clin Chim Acta 2017; 472:118-122. [PMID: 28778380 DOI: 10.1016/j.cca.2017.07.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 07/23/2017] [Accepted: 07/31/2017] [Indexed: 11/29/2022]
Abstract
BACKGROUND We quantified pyridoxal 5'-phosphate (PLP), pyridoxal (PL), and 4-pyridoxic acid (PA) in paired serum and cerebrospinal fluid (CSF) samples from children and investigated the effect of age on the concentrations and CSF-to-serum ratios of these vitamers. METHODS Serum and CSF samples prospectively collected from 49 pediatric patients were analyzed. PLP, PL, and PA were measured using high-performance liquid chromatography with fluorescence detection, using pre-column derivatization by semicarbazide. Effects of age on these vitamers, the PLP-to-PL ratio, CSF-to-serum PLP ratio, and CSF-to-serum PL ratio were evaluated using correlation analysis. RESULTS The PLP, PL, and PA concentrations in the serum and CSF were higher at younger ages, except for CSF PA concentrations that were mostly below the limit of detection (<1.2nmol/l). The PLP-to-PL ratios in the serum and CSF correlated positively with age. The CSF-to-serum PLP ratio and CSF-to-serum PL ratio were independent of age. CONCLUSIONS Age-related changes in PLP, PL, and PA in serum and in CSF from pediatric patients and CSF-to-serum ratios of PLP and PL demonstrated in this study will provide valuable information for evaluating PLP supply to the central nervous system from the peripheral blood.
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Affiliation(s)
- Tomoyuki Akiyama
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan; Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
| | - Yumiko Hayashi
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan
| | - Yoshiyuki Hanaoka
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan
| | - Takashi Shibata
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan
| | - Mari Akiyama
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan
| | - Hiroki Tsuchiya
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan; Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Tokito Yamaguchi
- Department of Pediatrics, NHO Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan
| | - Katsuhiro Kobayashi
- Department of Child Neurology, Okayama University Hospital, Okayama, Japan; Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
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94
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Abstract
OPINION STATEMENT In the absence of a culprit epileptogenic lesion, pharmacoresistant seizures should prompt the physician to consider potentially treatable metabolic epilepsies, especially in the presence of developmental delays. Even though the anti-seizure treatment of the epilepsies remains symptomatic and usually tailored to an electroclinical phenotype rather than to an underlying etiology, a thorough metabolic workup might reveal a disease with an etiology-specific treatment. Early diagnosis is essential in the case of treatable metabolic epilepsies allowing timely intervention. Despite the advances in genetic testing, biochemical testing including cerebrospinal fluid studies are still needed to expedite the diagnostic workup and potential therapeutic trials. The diagnostician should have a high index of suspicion despite potential clinical digressions from seminal publications describing the initial cases, as these index patients may represent the most severe form of the condition rather than its most common presenting form. The often gratifying developmental outcome and seizure control with early treatment calls for a prompt diagnostic consideration of treatable metabolic diseases; even though relatively rare or potentially only seemingly so.
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95
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Labella JI, Cantos R, Espinosa J, Forcada-Nadal A, Rubio V, Contreras A. PipY, a Member of the Conserved COG0325 Family of PLP-Binding Proteins, Expands the Cyanobacterial Nitrogen Regulatory Network. Front Microbiol 2017; 8:1244. [PMID: 28744260 PMCID: PMC5504682 DOI: 10.3389/fmicb.2017.01244] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 06/20/2017] [Indexed: 11/13/2022] Open
Abstract
Synechococcus elongatus PCC 7942 is a paradigmatic model organism for nitrogen regulation in cyanobacteria. Expression of genes involved in nitrogen assimilation is positively regulated by the 2-oxoglutarate receptor and global transcriptional regulator NtcA. Maximal activation requires the subsequent binding of the co-activator PipX. PII, a protein found in all three domains of life as an integrator of signals of the nitrogen and carbon balance, binds to PipX to counteract NtcA activity at low 2-oxoglutarate levels. PII-PipX complexes can also bind to the transcriptional regulator PlmA, whose regulon remains unknown. Here we expand the nitrogen regulatory network to PipY, encoded by the bicistronic operon pipXY in S. elongatus. Work with PipY, the cyanobacterial member of the widespread family of COG0325 proteins, confirms the conserved roles in vitamin B6 and amino/keto acid homeostasis and reveals new PLP-related phenotypes, including sensitivity to antibiotics targeting essential PLP-holoenzymes or synthetic lethality with cysK. In addition, the related phenotypes of pipY and pipX mutants are consistent with genetic interactions in the contexts of survival to PLP-targeting antibiotics and transcriptional regulation. We also showed that PipY overexpression increased the length of S. elongatus cells. Taken together, our results support a universal regulatory role for COG0325 proteins, paving the way to a better understanding of these proteins and of their connections with other biological processes.
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Affiliation(s)
- José I Labella
- Departamento de Fisiología, Genética y Microbiología, Universidad de AlicanteAlicante, Spain
| | - Raquel Cantos
- Departamento de Fisiología, Genética y Microbiología, Universidad de AlicanteAlicante, Spain
| | - Javier Espinosa
- Departamento de Fisiología, Genética y Microbiología, Universidad de AlicanteAlicante, Spain
| | - Alicia Forcada-Nadal
- Departamento de Fisiología, Genética y Microbiología, Universidad de AlicanteAlicante, Spain.,Instituto de Biomedicina de Valencia - Consejo Superior de Investigaciones CientíficasValencia, Spain
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia - Consejo Superior de Investigaciones CientíficasValencia, Spain.,Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras - Instituto de Salud Carlos IIIValencia, Spain
| | - Asunción Contreras
- Departamento de Fisiología, Genética y Microbiología, Universidad de AlicanteAlicante, Spain
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96
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Sharma S, Prasad AN. Inborn Errors of Metabolism and Epilepsy: Current Understanding, Diagnosis, and Treatment Approaches. Int J Mol Sci 2017; 18:ijms18071384. [PMID: 28671587 PMCID: PMC5535877 DOI: 10.3390/ijms18071384] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 06/21/2017] [Accepted: 06/23/2017] [Indexed: 12/22/2022] Open
Abstract
Inborn errors of metabolism (IEM) are a rare cause of epilepsy, but seizures and epilepsy are frequently encountered in patients with IEM. Since these disorders are related to inherited enzyme deficiencies with resulting effects on metabolic/biochemical pathways, the term “metabolic epilepsy” can be used to include these conditions. These epilepsies can present across the life span, and share features of refractoriness to anti-epileptic drugs, and are often associated with co-morbid developmental delay/regression, intellectual, and behavioral impairments. Some of these disorders are amenable to specific treatment interventions; hence timely and appropriate diagnosis is critical to improve outcomes. In this review, we discuss those disorders in which epilepsy is a dominant feature and present an approach to the clinical recognition, diagnosis, and management of these disorders, with a greater focus on primarily treatable conditions. Finally, we propose a tiered approach that will permit a clinician to systematically investigate, identify, and treat these rare disorders.
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Affiliation(s)
- Suvasini Sharma
- Department of Pediatrics, Lady Hardinge Medical College, New Delhi 110001, India.
| | - Asuri N Prasad
- Department of Pediatrics and Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Children's Hospital of Western Ontario and London Health Sciences Centre, London, ON N6A5W9, Canada.
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97
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Plecko B, Zweier M, Begemann A, Mathis D, Schmitt B, Striano P, Baethmann M, Vari MS, Beccaria F, Zara F, Crowther LM, Joset P, Sticht H, Papuc SM, Rauch A. Confirmation of mutations inPROSCas a novel cause of vitamin B6-dependent epilepsy. J Med Genet 2017; 54:809-814. [DOI: 10.1136/jmedgenet-2017-104521] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/01/2017] [Accepted: 03/01/2017] [Indexed: 11/03/2022]
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98
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Pena IA, MacKenzie A, Van Karnebeek CDM. Current knowledge for pyridoxine-dependent epilepsy: a 2016 update. Expert Rev Endocrinol Metab 2017; 12:5-20. [PMID: 30058881 DOI: 10.1080/17446651.2017.1273107] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Pyridoxine-dependent epilepsy (PDE) is a rare genetic condition characterized by intractable and recurrent neonatal seizures that are uniquely alleviated by high doses of pyridoxine (vitamin B6). This recessive disease is caused by mutations in ALDH7A1, a gene encoding Antiquitin, an enzyme central to lysine degradation. This results in the pathogenic accumulation of the lysine intermediates Aminoadipate Semialdehyde (AASA) and its cyclic equilibrium form Piperideine-6-carboxylate (P6C) in body fluids; P6C reacts with pyridoxal-5'-phosphate (PLP, the active form of vitamin B6) causing its inactivation and leading to pyridoxine-dependent seizures. While PDE is responsive to pharmacological dosages of pyridoxine, despite lifelong supplementation, neurodevelopment delays are observed in >75% of PDE cases. Thus, adjunct treatment strategies are emerging to both improve seizure control and moderate the delays in cognition. These adjunctive therapies, lysine restriction and arginine supplementation, separately or in combination (with pyridoxine thus termed 'triple therapy'), have shown promising results and are recommended in all PDE patients. Other new therapeutic strategies currently in preclinical phase of study include antisense therapy and substrate reduction therapy. We present here a comprehensive review of current treatment options as well as PDE phenotype, differential diagnosis, current management and views upon the future of PDE research.
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Affiliation(s)
- Izabella Agostinho Pena
- a Children's Hospital of Eastern Ontario (CHEO) Research Institute , Ottawa , ON , Canada
- b Department of Cellular and Molecular Medicine , University of Ottawa , Ottawa , ON , Canada
| | - Alex MacKenzie
- a Children's Hospital of Eastern Ontario (CHEO) Research Institute , Ottawa , ON , Canada
- b Department of Cellular and Molecular Medicine , University of Ottawa , Ottawa , ON , Canada
| | - Clara D M Van Karnebeek
- c Department of Pediatrics, BC Children's Hospital Research Institute, Centre for Molecular Medicine and Therapeutics , University of British Columbia , Vancouver BC , Canada
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