1
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Mastrangelo M, Gasparri V, Bernardi K, Foglietta S, Ramantani G, Pisani F. Epilepsy Phenotypes of Vitamin B6-Dependent Diseases: An Updated Systematic Review. CHILDREN 2023; 10:children10030553. [PMID: 36980111 PMCID: PMC10047402 DOI: 10.3390/children10030553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/12/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023]
Abstract
Background: Vitamin B6-dependent epilepsies include treatable diseases responding to pyridoxine or pyridoxal-5Iphosphate (ALDH7A1 deficiency, PNPO deficiency, PLP binding protein deficiency, hyperprolinemia type II and hypophosphatasia and glycosylphosphatidylinositol anchor synthesis defects). Patients and methods: We conducted a systematic review of published pediatric cases with a confirmed molecular genetic diagnosis of vitamin B6-dependent epilepsy according to PRISMA guidelines. Data on demographic features, seizure semiology, EEG patterns, neuroimaging, treatment, and developmental outcomes were collected. Results: 497 published patients fulfilled the inclusion criteria. Seizure onset manifested at 59.8 ± 291.6 days (67.8% of cases in the first month of life). Clonic, tonic-clonic, and myoclonic seizures accounted for two-thirds of the cases, while epileptic spasms were observed in 7.6%. Burst-suppression/suppression-burst represented the most frequently reported specific EEG pattern (14.4%), mainly in PLPB, ALDH7A1, and PNPO deficiency. Pyridoxine was administered to 312 patients (18.5% intravenously, 76.9% orally, 4.6% not specified), and 180 also received antiseizure medications. Pyridoxine dosage ranged between 1 and 55 mg/kg/die. Complete seizure freedom was achieved in 160 patients, while a significant seizure reduction occurred in 38. PLP, lysine-restricted diet, and arginine supplementation were used in a small proportion of patients with variable efficacy. Global developmental delay was established in 30.5% of a few patients in whom neurocognitive tests were performed. Conclusions: Despite the wide variability, the most frequent hallmarks of the epilepsy phenotype in patients with vitamin B6-dependent seizures include generalized or focal motor seizure semiology and a burst suppression/suppression burst pattern in EEG.
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Affiliation(s)
- Mario Mastrangelo
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
- Department of Neuroscience/Mental Health, Azienda Ospedaliero-Universitaria Policlinico Umberto I, 00161 Rome, Italy
- Correspondence:
| | - Valentina Gasparri
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
| | - Katerina Bernardi
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
| | - Silvia Foglietta
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
| | - Georgia Ramantani
- Department of Neuropediatrics, University Children’s Hospital Zurich and University of Zurich, 8032 Zurich, Switzerland
| | - Francesco Pisani
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, 00185 Rome, Italy
- Department of Neuroscience/Mental Health, Azienda Ospedaliero-Universitaria Policlinico Umberto I, 00161 Rome, Italy
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2
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Raimann A, Haberler C, Patsch J, Ertl DA, Sadeghi K, Freilinger M, Lang S, Schmook M, Plecko B, Haeusler G. Lethal Encephalopathy in an Infant with Hypophosphatasia despite Enzyme Replacement Therapy. Horm Res Paediatr 2022; 94:390-398. [PMID: 34673643 DOI: 10.1159/000520341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/14/2021] [Indexed: 11/19/2022] Open
Abstract
Hypophosphatasia (HPP) is an inborn error of metabolism caused by loss-of-function mutations in the biomineralization-associated alkaline phosphatase gene, encoding tissue-nonspecific alkaline phosphatase (TNSALP). Symptoms include skeletal hypomineralization and extra-skeletal manifestations such as pyridoxine (B6)-responsive seizures due to impaired cerebral B6 passage. Since the introduction of enzyme replacement therapy (ERT), skeletal manifestations and B6-responsive seizures were reported to improve significantly. Nevertheless, there is an increasing evidence of B6-independent neurological manifestation of HPP including HPP-associated encephalopathy. Here, we present for the first time the brain alterations of an infant with neonatal HPP who died of neurological complications at the age of 5 months despite early initiation of ERT. CSF analysis showed normal concentrations of biogenic amines reflecting sufficient intracellular B6 availability. Postmortem histopathology revealed severe, localized affection of the cerebral cortex including cortical lesions in layers 2 and 3 in direct proximity to TNSALP-expressing neurons and hippocampal sclerosis. Our findings confirm that TNSALP deficiency may lead to a severe encephalopathy. We hypothesize that HPP-associated encephalopathy resistant to currently available ERT may develop in addition and probably independently of typical B6-responsive seizures in some patients. Prospective, controlled studies with close neurological follow-up including brain imaging are needed to identify patients at risk for severe neurological symptoms despite ERT.
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Affiliation(s)
- Adalbert Raimann
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.,Vienna Bone and Growth Center, Vienna, Austria
| | | | - Janina Patsch
- Vienna Bone and Growth Center, Vienna, Austria.,Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Diana-Alexandra Ertl
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.,Vienna Bone and Growth Center, Vienna, Austria
| | - Kambis Sadeghi
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Michael Freilinger
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Susanna Lang
- Department of Pathology, Medical University of Vienna, Vienna, Austria
| | - Maria Schmook
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Barbara Plecko
- Department of Pediatrics and Adolescent Medicine, Medical University of Graz, Graz, Austria
| | - Gabriele Haeusler
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.,Vienna Bone and Growth Center, Vienna, Austria
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3
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Goettsch C, Strzelecka-Kiliszek A, Bessueille L, Quillard T, Mechtouff L, Pikula S, Canet-Soulas E, Luis MJ, Fonta C, Magne D. TNAP as a therapeutic target for cardiovascular calcification: a discussion of its pleiotropic functions in the body. Cardiovasc Res 2022; 118:84-96. [PMID: 33070177 PMCID: PMC8752354 DOI: 10.1093/cvr/cvaa299] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/11/2020] [Accepted: 10/06/2020] [Indexed: 12/15/2022] Open
Abstract
Cardiovascular calcification (CVC) is associated with increased morbidity and mortality. It develops in several diseases and locations, such as in the tunica intima in atherosclerosis plaques, in the tunica media in type 2 diabetes and chronic kidney disease, and in aortic valves. In spite of the wide occurrence of CVC and its detrimental effects on cardiovascular diseases (CVD), no treatment is yet available. Most of CVC involve mechanisms similar to those occurring during endochondral and/or intramembranous ossification. Logically, since tissue-nonspecific alkaline phosphatase (TNAP) is the key-enzyme responsible for skeletal/dental mineralization, it is a promising target to limit CVC. Tools have recently been developed to inhibit its activity and preclinical studies conducted in animal models of vascular calcification already provided promising results. Nevertheless, as its name indicates, TNAP is ubiquitous and recent data indicate that it dephosphorylates different substrates in vivo to participate in other important physiological functions besides mineralization. For instance, TNAP is involved in the metabolism of pyridoxal phosphate and the production of neurotransmitters. TNAP has also been described as an anti-inflammatory enzyme able to dephosphorylate adenosine nucleotides and lipopolysaccharide. A better understanding of the full spectrum of TNAP's functions is needed to better characterize the effects of TNAP inhibition in diseases associated with CVC. In this review, after a brief description of the different types of CVC, we describe the newly uncovered additional functions of TNAP and discuss the expected consequences of its systemic inhibition in vivo.
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Affiliation(s)
- Claudia Goettsch
- Department of Internal Medicine I, Cardiology, Medical Faculty, RWTH Aachen
University, Aachen, Germany
| | - Agnieszka Strzelecka-Kiliszek
- Laboratory of Biochemistry of Lipids, Nencki Institute of Experimental
Biology, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Laurence Bessueille
- Institute of Molecular and Supramolecular Chemistry and Biochemistry
(ICBMS), UMR CNRS 5246, Université Claude Bernard Lyon 1, Bâtiment
Raulin, 43 Bd du 11 novembre 1918, Lyon 69622 Villeurbanne Cedex, France
| | - Thibaut Quillard
- PHY-OS Laboratory, UMR 1238 INSERM, Université de Nantes, CHU
de Nantes, France
| | - Laura Mechtouff
- Stroke Department, Hospices Civils de Lyon, France
- CREATIS Laboratory, CNRS UMR 5220, Inserm U1044, Université Claude Bernard
Lyon 1, Lyon, France
| | - Slawomir Pikula
- Laboratory of Biochemistry of Lipids, Nencki Institute of Experimental
Biology, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Emmanuelle Canet-Soulas
- CarMeN Laboratory, Univ Lyon, INSERM, INRA, INSA Lyon, Université Claude
Bernard Lyon 1, Lyon, France
| | - Millan Jose Luis
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery
Institute, La Jolla, CA 92037, USA
| | - Caroline Fonta
- Brain and Cognition Research Center CerCo, CNRS UMR5549, Université de
Toulouse, France
| | - David Magne
- Institute of Molecular and Supramolecular Chemistry and Biochemistry
(ICBMS), UMR CNRS 5246, Université Claude Bernard Lyon 1, Bâtiment
Raulin, 43 Bd du 11 novembre 1918, Lyon 69622 Villeurbanne Cedex, France
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4
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Michigami T, Ohata Y, Fujiwara M, Mochizuki H, Adachi M, Kitaoka T, Kubota T, Sawai H, Namba N, Hasegawa K, Fujiwara I, Ozono K. Clinical Practice Guidelines for Hypophosphatasia. Clin Pediatr Endocrinol 2020; 29:9-24. [PMID: 32029969 PMCID: PMC6958520 DOI: 10.1297/cpe.29.9] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 08/16/2019] [Indexed: 12/17/2022] Open
Abstract
Hypophosphatasia (HPP) is a rare bone disease caused by inactivating mutations in the
ALPL gene, which encodes tissue-nonspecific alkaline phosphatase
(TNSALP). Patients with HPP have varied clinical manifestations and are classified based
on the age of onset and severity. Recently, enzyme replacement therapy using bone-targeted
recombinant alkaline phosphatase (ALP) has been developed, leading to improvement in the
prognosis of patients with life-threatening HPP. Considering these recent advances,
clinical practice guidelines have been generated to provide physicians with guides for
standard medical care for HPP and to support their clinical decisions. A task force was
convened for this purpose, and twenty-one clinical questions (CQs) were formulated,
addressing the issues of clinical manifestations and diagnosis (7 CQs) and those of
management and treatment (14 CQs). A systematic literature search was conducted using
PubMed/MEDLINE, and evidence-based recommendations were developed. The guidelines have
been modified according to the evaluations and suggestions from the Clinical Guideline
Committee of The Japanese Society for Pediatric Endocrinology (JSPE) and public comments
obtained from the members of the JSPE and a Japanese HPP patient group, and then approved
by the Board of Councils of the JSPE. We anticipate that the guidelines will be revised
regularly and updated.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, Osaka, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Yasuhisa Ohata
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Makoto Fujiwara
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Hiroshi Mochizuki
- Division of Endocrinology and Metabolism, Saitama Children's Medical Center, Saitama, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Masanori Adachi
- Department of Endocrinology and Metabolism, Kanagawa Children's Medical Center, Kanagawa, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Taichi Kitaoka
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Takuo Kubota
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Hideaki Sawai
- Department of Obstetrics and Gynecology, Hyogo College of Medicine, Hyogo, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Noriyuki Namba
- Division of Pediatrics and Perinatology, Tottori University Faculty of Medicine, Tottori, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Kosei Hasegawa
- Department of Pediatrics, Okayama University Hospital, Okayama, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Ikuma Fujiwara
- Department of Pediatrics, Sendai City Hospital, Miyagi, Japan.,Task Force for Hypophosphatasia Guidelines
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.,Task Force for Hypophosphatasia Guidelines
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5
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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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6
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Luo E, Shi B, Chen QM, Zhou XD. [Dental-craniofacial manifestation and treatment of rare diseases in China]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2019; 37:130-142. [PMID: 31168978 PMCID: PMC7030144 DOI: 10.7518/hxkq.2019.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/16/2019] [Indexed: 02/05/2023]
Abstract
Rare diseases are genetic, chronic, and incurable disorders with relatively low prevalence. Thus, diagnosis and management strategies for such diseases are currently limited. This situation is exacerbated by insufficient medical sources for these diseases. The National Health and Health Committee of China recently first provided a clear definition of 121 rare diseases in the Chinese population. In this study, we summarize several dental-craniofacial manifestations associated with some rare diseases to provide a reference for dentists and oral maxillofacial surgeons aiming at fast-tracking diagnosis for the management of these rare diseases.
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Affiliation(s)
- En Luo
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Bing Shi
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Qian-Ming Chen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xue-Dong Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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7
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Luo E, Liu H, Zhao Q, Shi B, Chen Q. Dental-craniofacial manifestation and treatment of rare diseases. Int J Oral Sci 2019; 11:9. [PMID: 30783081 PMCID: PMC6381182 DOI: 10.1038/s41368-018-0041-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/22/2018] [Accepted: 10/28/2018] [Indexed: 02/05/2023] Open
Abstract
Rare diseases are usually genetic, chronic and incurable disorders with a relatively low incidence. Developments in the diagnosis and management of rare diseases have been relatively slow due to a lack of sufficient profit motivation and market to attract research by companies. However, due to the attention of government and society as well as economic development, rare diseases have been gradually become an increasing concern. As several dental-craniofacial manifestations are associated with rare diseases, we summarize them in this study to help dentists and oral maxillofacial surgeons provide an early diagnosis and subsequent management for patients with these rare diseases.
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Affiliation(s)
- En Luo
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Hanghang Liu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Qiucheng Zhao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Bing Shi
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
| | - Qianming Chen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
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8
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Abstract
The pathophysiology of the neuromuscular manifestations of hypophosphatasia (HPP) remains unknown. Pyridoxine-sensitive seizures characterize severe forms of infantile HPP. Young children and infants affected with severe forms of HPP, but also adults often present with myopathy characterized by hypotonia or muscle weakness. Chronic pain, of unclear mechanism is also often present. Tissue-non-specific alkaline phosphatase (Alkaline Phosphatase-Liver/Bone/Kidney [ALPL]) is expressed in brain neuronal cell and in muscle cells during development and adulthood. The knockout of the ALPL impacts neuronal functions in animal models. This may occur through metabolic anomalies involving gamma-aminobutyric acid (GABA) and other neurotransmitters via the metabolism of pyridoxal phosphate (vitamin B6) and phosphoethanolamine. In this context, a greater understanding of the neuromuscular pathophysiology of HPP is critical to assess the potential impact of new therapies.
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9
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Manea E. A step closer in defining glycosylphosphatidylinositol anchored proteins role in health and glycosylation disorders. Mol Genet Metab Rep 2018; 16:67-75. [PMID: 30094187 PMCID: PMC6080220 DOI: 10.1016/j.ymgmr.2018.07.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/21/2018] [Accepted: 07/21/2018] [Indexed: 12/18/2022] Open
Abstract
Glycosylphosphatidylinositol anchored proteins (GPI-APs) represent a class of soluble proteins attached to the external leaflet of the plasma membrane by a post-translation modification, the GPI anchor. The 28 genes currently involved in the synthesis and remodelling of the GPI anchor add to the ever-growing class of congenital glycosylation disorders. Recent advances in next generation sequencing technology have led to the discovery of Mabry disease and CHIME syndrome genetic aetiology. Moreover, with each described mutation known phenotypes expand and new ones emerge without clear genotype-phenotype correlation. A protein database search was made for human GPI-APs with defined pathology to help building-up a physio-pathological mechanism from a clinical perspective. GPI-APs function in vitamin-B6 and folate transport, nucleotide metabolism and lipid homeostasis. Defining GPI-APs role in disease bears significant clinical implications.
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Abstract
We review here clinical, pathophysiological, diagnostic, genetic and molecular aspects of Hypophosphatasia (HPP), a rare inherited metabolic disorder. The clinical presentation is a continuum ranging from a prenatal lethal form with no skeletal mineralization to a mild form with late adult onset presenting with nonpathognomonic symptoms. The prevalence of severe forms is low, whereas less severe forms are more frequently observed. The disease is caused by loss-of-function mutations in the ALPL gene encoding the Tissue Nonspecific Alkaline Phosphatase (TNSALP), a central regulator of mineralization. Severe forms are recessively inherited, whereas moderate forms are either recessively or dominantly inherited, and the more severe the disease is, the more often it is subject to recessive inheritance. The diagnosis is based on a constantly low alkaline phosphatase (AP) activity in serum and genetic testing that identifies ALPL mutations. More than 340 mutations have been identified and are responsible for the extraordinary clinical heterogeneity. A clear but imperfect genotype-phenotype correlation has been observed, suggesting that other genetic or environmental factors modulate the phenotype. Enzyme replacement therapy is now available for HPP, and other approaches, such as gene therapy, are currently being investigated.
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Affiliation(s)
- Etienne Mornet
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 177 rue de Versailles, 78150 Le Chesnay, France.
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11
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Infantile hypophosphatasia combined with vitamin B6-responsive seizures and reticular formation lesions on magnetic resonance imaging: A case report. Brain Dev 2018; 40:140-144. [PMID: 28802630 DOI: 10.1016/j.braindev.2017.07.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 07/21/2017] [Accepted: 07/24/2017] [Indexed: 11/23/2022]
Abstract
BACKGROUND Hypophosphatasia (HPP) is a rare genetic disorder characterized by rachitic bone manifestations and a low serum alkaline phosphatase (ALP) level. It is caused by mutations in the tissue non-specific alkaline phosphatase (TNSALP) gene, which encodes the tissue non-specific isozyme of ALP. HPP patients exhibit various presentations depending on their age at onset, such as infantile HPP combined with vitamin B6-responsive seizures. CASE PRESENTATION A newborn with infantile HPP presented with tonic convulsions from day 5 after birth and received intravenous vitamin B6 (10mg/kg/day pyridoxal phosphate). Eleven days later, frequent apneic episodes occurred, and head magnetic resonance imaging (MRI) showed bilateral reticular formation lesions in the brain stem, including the medulla oblongata. After the pyridoxal phosphate dose was increased (to 40mg/kg/day), the patient's seizures and apnea resolved, and her MRI findings also improved. Genetic testing revealed that she was homozygous for the 1559delT mutation of TNSALP. CONCLUSIONS High-dose pyridoxal phosphate is a useful treatment for HPP-induced seizures and might improve reticular formation lesions.
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12
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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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Guerriero RM, Patel AA, Walsh B, Baumer FM, Shah AS, Peters JM, Rodan LH, Agrawal PB, Pearl PL, Takeoka M. Systemic Manifestations in Pyridox(am)ine 5'-Phosphate Oxidase Deficiency. Pediatr Neurol 2017; 76:47-53. [PMID: 28985901 PMCID: PMC6008785 DOI: 10.1016/j.pediatrneurol.2017.05.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 05/24/2017] [Accepted: 05/28/2017] [Indexed: 01/27/2023]
Abstract
OBJECTIVE Pyridoxine is converted to its biologically active form pyridoxal-5-phosphate (P5P) by the enzyme pyridox(am)ine 5'-phosphate oxidase and serves as a cofactor in nearly 200 reactions in the central nervous system. Pyridox(am)ine 5'-phosphate oxidase deficiency leads to P5P dependent epilepsy, typically a neonatal- or infantile-onset epileptic encephalopathy treatable with P5P or in some cases, pyridoxine. Following identification of retinopathy in a patient with pyridox(am)ine 5'-phosphate oxidase deficiency that was reversible with P5P therapy, we describe the systemic manifestations of pyridox(am)ine 5'-phosphate oxidase deficiency. METHODS A series of six patients with homozygous mutations of PNPO, the gene coding pyridox(am)ine 5'-phosphate oxidase, were evaluated in our center over the course of two years for phenotyping of neurological and systemic manifestations. RESULTS Five of six were born prematurely, three had anemia and failure to thrive, and two had elevated alkaline phosphatase. A movement disorder was observed in two children, and a reversible retinopathy was observed in the most severely affected infant. All patients had neonatal-onset epilepsy and were on a continuum of developmental delay to profound encephalopathy. Electroencephalographic features included background slowing and disorganization, absent sleep features, and multifocal and generalized epileptiform discharges. All the affected probands carried a homozygous PNPO mutation (c.674 G>T, c.686 G>A and c.352G>A). CONCLUSION In addition to the well-described epileptic encephalopathy, pyridox(am)ine 5'-phosphate oxidase deficiency causes a range of neurological and systemic manifestations. A movement disorder, developmental delay, and encephalopathy, as well as retinopathy, anemia, and failure to thrive add to the broadening clinical spectrum of P5P dependent epilepsy.
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Affiliation(s)
- Réjean M. Guerriero
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts,Division of Pediatric and Developmental Neurology, Department of Neurology, Washington University School of Medicine, St. Louis, Missouri,Communications should be addressed to: Dr. Guerriero; Division of Pediatric and Developmental Neurology; Department of Neurology; Washington University School of Medicine; Campus Box 8111; 660 South Euclid Ave; St. Louis, MO 63110.
| | - Archana A. Patel
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Brian Walsh
- Division of Newborn Medicine, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Fiona M. Baumer
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Ankoor S. Shah
- Department of Ophthalmology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jurriaan M. Peters
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Lance H. Rodan
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Pankaj B. Agrawal
- Division of Newborn Medicine, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts,Division of Genetics and Genomics, Department of Pediatrics, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts,Manton Center for Orphan Disease Research, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Phillip L. Pearl
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Masanori Takeoka
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
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Rader BA. Alkaline Phosphatase, an Unconventional Immune Protein. Front Immunol 2017; 8:897. [PMID: 28824625 PMCID: PMC5540973 DOI: 10.3389/fimmu.2017.00897] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/13/2017] [Indexed: 12/16/2022] Open
Abstract
Recent years have seen an increase in the number of studies focusing on alkaline phosphatases (APs), revealing an expanding complexity of function of these enzymes. Of the four human AP (hAP) proteins, most is known about tissue non-specific AP (TNAP) and intestinal AP (IAP). This review highlights current understanding of TNAP and IAP in relation to human health and disease. TNAP plays a role in multiple processes, including bone mineralization, vitamin B6 metabolism, and neurogenesis, is the genetic cause of hypophosphatasia, influences inflammation through regulation of purinergic signaling, and has been implicated in Alzheimer's disease. IAP regulates fatty acid absorption and has been implicated in the regulation of diet-induced obesity and metabolic syndrome. IAP and TNAP can dephosphorylate bacterial-derived lipopolysaccharide, and IAP has been identified as a potential regulator of the composition of the intestinal microbiome, an evolutionarily conserved function. Endogenous and recombinant bovine APs and recombinant hAPs are currently being explored for their potential as pharmacological agents to treat AP-associated diseases and mitigate multiple sources of inflammation. Continued research on these versatile proteins will undoubtedly provide insight into human pathophysiology, biochemistry, and the human holobiont.
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Affiliation(s)
- Bethany A Rader
- Department of Microbiology, Southern Illinois University, Carbondale, IL, United States
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Cruz T, Gleizes M, Balayssac S, Mornet E, Marsal G, Millán JL, Malet-Martino M, Nowak LG, Gilard V, Fonta C. Identification of altered brain metabolites associated with TNAP activity in a mouse model of hypophosphatasia using untargeted NMR-based metabolomics analysis. J Neurochem 2017; 140:919-940. [PMID: 28072448 DOI: 10.1111/jnc.13950] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 12/18/2016] [Accepted: 01/04/2017] [Indexed: 12/20/2022]
Abstract
Tissue non-specific alkaline phosphatase (TNAP) is a key player of bone mineralization and TNAP gene (ALPL) mutations in human are responsible for hypophosphatasia (HPP), a rare heritable disease affecting the mineralization of bones and teeth. Moreover, TNAP is also expressed by brain cells and the severe forms of HPP are associated with neurological disorders, including epilepsy and brain morphological anomalies. However, TNAP's role in the nervous system remains poorly understood. To investigate its neuronal functions, we aimed to identify without any a priori the metabolites regulated by TNAP in the nervous tissue. For this purpose we used 1 H- and 31 P NMR to analyze the brain metabolome of Alpl (Akp2) mice null for TNAP function, a well-described model of infantile HPP. Among 39 metabolites identified in brain extracts of 1-week-old animals, eight displayed significantly different concentration in Akp2-/- compared to Akp2+/+ and Akp2+/- mice: cystathionine, adenosine, GABA, methionine, histidine, 3-methylhistidine, N-acetylaspartate (NAA), and N-acetyl-aspartyl-glutamate, with cystathionine and adenosine levels displaying the strongest alteration. These metabolites identify several biochemical processes that directly or indirectly involve TNAP function, in particular through the regulation of ecto-nucleotide levels and of pyridoxal phosphate-dependent enzymes. Some of these metabolites are involved in neurotransmission (GABA, adenosine), in myelin synthesis (NAA, NAAG), and in the methionine cycle and transsulfuration pathway (cystathionine, methionine). Their disturbances may contribute to the neurodevelopmental and neurological phenotype of HPP.
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Affiliation(s)
- Thomas Cruz
- Groupe de RMN Biomédicale, Laboratoire SPCMIB (CNRS UMR 5068), Université Paul Sabatier, Université de Toulouse, Toulouse Cedex, France
| | - Marie Gleizes
- Centre de Recherche Cerveau et Cognition (CerCo), Université de Toulouse UPS; CNRS UMR 5549, Toulouse, France
| | - Stéphane Balayssac
- Groupe de RMN Biomédicale, Laboratoire SPCMIB (CNRS UMR 5068), Université Paul Sabatier, Université de Toulouse, Toulouse Cedex, France
| | - Etienne Mornet
- Unité de Génétique Constitutionnelle Prénatale et Postnatale, Service de Biologie, Centre Hospitalier de Versailles, Le Chesnay, France
| | - Grégory Marsal
- Centre de Recherche Cerveau et Cognition (CerCo), Université de Toulouse UPS; CNRS UMR 5549, Toulouse, France
| | - José Luis Millán
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Myriam Malet-Martino
- Groupe de RMN Biomédicale, Laboratoire SPCMIB (CNRS UMR 5068), Université Paul Sabatier, Université de Toulouse, Toulouse Cedex, France
| | - Lionel G Nowak
- Centre de Recherche Cerveau et Cognition (CerCo), Université de Toulouse UPS; CNRS UMR 5549, Toulouse, France
| | - Véronique Gilard
- Groupe de RMN Biomédicale, Laboratoire SPCMIB (CNRS UMR 5068), Université Paul Sabatier, Université de Toulouse, Toulouse Cedex, France
| | - Caroline Fonta
- Centre de Recherche Cerveau et Cognition (CerCo), Université de Toulouse UPS; CNRS UMR 5549, Toulouse, France
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Pyridoxine-Dependent Epilepsy: An Expanding Clinical Spectrum. Pediatr Neurol 2016; 59:6-12. [PMID: 26995068 DOI: 10.1016/j.pediatrneurol.2015.12.013] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 12/16/2015] [Accepted: 12/18/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND Pyridoxine-dependent epilepsy is a rare autosomal recessive epileptic encephalopathy caused by antiquitin (ALDH7A1) deficiency. In spite of adequate seizure control, 75% of patients suffer intellectual developmental disability. Antiquitin deficiency affects lysine catabolism resulting in accumulation of α-aminoadipic semialdehyde/pyrroline 6' carboxylate and pipecolic acid. Beside neonatal refractory epileptic encephalopathy, numerous neurological manifestations and metabolic/biochemical findings have been reported. METHODS AND RESULTS We present a phenotypic spectrum of antiquitin deficiency based on a literature review (2006 to 2015) of reports (n = 49) describing the clinical presentation of confirmed patients (n > 200) and a further six patient vignettes. Possible presentations include perinatal asphyxia; neonatal withdrawal syndrome; sepsis; enterocolitis; hypoglycemia; neuroimaging abnormalities (corpus callosum and cerebellar abnormalities, hemorrhage, white matter lesions); biochemical abnormalities (lactic acidosis, electrolyte disturbances, neurotransmitter abnormalities); and seizure response to pyridoxine, pyridoxal-phosphate, and folinic acid dietary interventions. DISCUSSION The phenotypic spectrum of pyridoxine-dependent epilepsy is wide, including a myriad of neurological and systemic symptoms. Its hallmark feature is refractory seizures during the first year of life. Given its amenability to treatment with lysine-lowering strategies in addition to pyridoxine supplementation for optimal seizure control and developmental outcomes, early diagnosis of pyridoxine-dependent epilepsy is essential. All infants presenting with unexplained seizures should be screened for antiquitin deficiency by determination of α-aminoadipic semialdehyde/pyrroline 6' carboxylate (in urine, plasma or cerebrospinal fluid) and ALDH7A1 molecular analysis.
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Abstract
Hypophosphatasia is a rare disorder due to a mutation in the ALPL gene encoding the alkaline phosphatase (ALP) leading to a diminished activity of the enzyme in bone, liver, and kidney. Hypophosphatasia is a heterogeneous disease, ranging from extreme life-threatening forms revealed at birth in young infants presenting with severely impaired bone mineralization, seizures, and hypercalcemia, to young adults with premature exfoliation of their teeth without any other symptom. We will review the challenges of the clinical, biochemical, radiological, and genetic diagnosis. Schematically, the diagnosis relies on low ALP levels and, in most cases, on the genetic defect in the ALPL gene. An enzyme replacement therapy is now developed for hypophosphatasia; early results in the severe form of the disease are extremely encouraging. However, multidisciplinary care remains the core of treatment of hypophosphatasia encompassing nutritional support, adjustment of calcium and phosphate intake, monitoring of vitamin D levels, careful and personalized physical therapy, and regular dental monitoring and care.
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Affiliation(s)
- Agnès Linglart
- Department of Pediatric Endocrinology and Diabetology for Children, APHP, Bicêtre Paris Sud, Le Kremlin Bicêtre, 94270, France.
- APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism and Plateforme d'Expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, 94270, France.
| | - Martin Biosse-Duplan
- APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism and Plateforme d'Expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, 94270, France
- Department of Odontology, APHP, Bretonneau Paris Nord Val de Seine, Paris, 75018, France
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Multiple Functions of MSCA-1/TNAP in Adult Mesenchymal Progenitor/Stromal Cells. Stem Cells Int 2015; 2016:1815982. [PMID: 26839555 PMCID: PMC4709781 DOI: 10.1155/2016/1815982] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 09/30/2015] [Indexed: 01/09/2023] Open
Abstract
Our knowledge about mesenchymal stem cells has considerably grown in the last years. Since the proof of concept of the existence of such cells in the 70s by Friedenstein et al., a growing mass of reports were conducted for a better definition of these cells and for the reevaluation from the term “mesenchymal stem cells” to the term “mesenchymal stromal cells (MSCs).” Being more than a semantic shift, concepts behind this new terminology reveal the complexity and the heterogeneity of the cells grouped in MSC family especially as these cells are present in nearly all adult tissues. Recently, mesenchymal stromal cell antigen-1 (MSCA-1)/tissue nonspecific alkaline phosphatase (TNAP) was described as a new cell surface marker of MSCs from different tissues. The alkaline phosphatase activity of this protein could be involved in wide range of MSC features described below from cell differentiation to immunomodulatory properties, as well as occurrence of pathologies. The present review aims to decipher and summarize the role of TNAP in progenitor cells from different tissues focusing preferentially on brain, bone marrow, and adipose tissue.
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Kántor O, Varga A, Kovács-Öller T, Énzsöly A, Balogh L, Baksa G, Szepessy Z, Fonta C, Roe AW, Nitschke R, Szél Á, Négyessy L, Völgyi B, Lukáts Á. TNAP activity is localized at critical sites of retinal neurotransmission across various vertebrate species. Cell Tissue Res 2014; 358:85-98. [PMID: 24988913 DOI: 10.1007/s00441-014-1944-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 06/05/2014] [Indexed: 12/01/2022]
Abstract
Evidence is emerging with regard to the role of tissue non-specific alkaline phosphatase (TNAP) in neural functions. As an ectophosphatase, this enzyme might influence neural activity and synaptic transmission in diverse ways. The localization of the enzyme in known neural circuits, such as the retina, might significantly advance an understanding of its role in normal and pathological functioning. However, the presence of TNAP in the retina is scarcely investigated. Our multispecies comparative study (zebrafish, cichlid, frog, chicken, mouse, rat, golden hamster, guinea pig, rabbit, sheep, cat, dog, ferret, squirrel monkey, human) using enzyme histochemistry and Western blots has shown the presence of TNAP activity in the retina of several mammalian species, including humans. Although the TNAP activity pattern varies across species, we have observed the following trends: (1) in all investigated species (except golden hamster), retinal vessels display TNAP activity; (2) TNAP activity consistently occurs in the photoreceptor layer; (3) in majority of the investigated species, marked TNAP activity is present in the outer and inner plexiform layers. In zebrafish, frog, chicken, guinea pig, and rat, TNAP histochemistry has revealed several sublayers of the inner plexiform layer. Frog, golden hamster, guinea pig, mouse, and human retinas possess a subpopulation of amacrine cells positively staining for TNAP activity. The expression of TNAP in critical sites of retinal signal transmission across a wide range of species suggests its fundamental, evolutionally conserved role in vision.
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Affiliation(s)
- Orsolya Kántor
- Department of Anatomy, Histology and Embryology, Semmelweis University, Tűzoltó u. 58, Budapest, 1094, Hungary,
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Comments on 'Infantile hypophosphatasia without bone deformities presenting with severe pyridoxine-resistant seizures' in Molecular Genetics and Metabolism' 2014 Mar;111(3):404-7 by M.G. de Roo, N.G. Abeling, C.B. Majoie, A.M. Bosch, J.H. Koelman, J.M. Cobben, M. Duran, B.T. Poll-The. Mol Genet Metab Rep 2014; 1:220-222. [PMID: 27896090 PMCID: PMC5121321 DOI: 10.1016/j.ymgmr.2014.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 04/08/2014] [Indexed: 11/20/2022] Open
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