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Jin C, Yonezawa A. Recent advances in riboflavin transporter RFVT and its genetic disease. Pharmacol Ther 2021; 233:108023. [PMID: 34662687 DOI: 10.1016/j.pharmthera.2021.108023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/30/2021] [Accepted: 10/12/2021] [Indexed: 12/20/2022]
Abstract
Riboflavin (vitamin B2) is essential for cellular growth and function. It is enzymatically converted to flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which participate in the metabolic oxidation-reduction reactions of carbohydrates, amino acids, and lipids. Human riboflavin transporters RFVT1, RFVT2, and RFVT3 have been identified and characterized since 2008. They are highly specific transporters of riboflavin. RFVT3 has functional characteristics different from those of RFVT1 and RFVT2. RFVT3 contributes to absorption in the small intestine, reabsorption in the kidney, and transport to the fetus in the placenta, while RFVT2 mediates the tissue distribution of riboflavin from the blood. Several mutations in the SLC52A2 gene encoding RFVT2 and the SLC52A3 gene encoding RFVT3 were found in patients with a rare neurological disorder known as Brown-Vialetto-Van Laere syndrome. These patients commonly present with bulbar palsy, hearing loss, muscle weakness, and respiratory symptoms in infancy or later in childhood. A decrease in plasma riboflavin levels has been observed in several cases. Recent studies on knockout mice and patient-derived cells have advanced the understanding of these mechanisms. Here, we summarize novel findings on RFVT1-3 and their genetic diseases and discuss their potential as therapeutic drugs.
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Affiliation(s)
- Congyun Jin
- Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Graduate School of Pharmaceutical Sciences, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Atsushi Yonezawa
- Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Graduate School of Pharmaceutical Sciences, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
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Carreau C, Benoit C, Ahle G, Cauquil C, Roubertie A, Lenglet T, Cosgrove J, Meunier I, Veauville-Merllié A, Acquaviva-Bourdain C, Nadjar Y. Late-onset riboflavin transporter deficiency: a treatable mimic of various motor neuropathy aetiologies. J Neurol Neurosurg Psychiatry 2020; 92:jnnp-2020-323304. [PMID: 33087424 DOI: 10.1136/jnnp-2020-323304] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 07/27/2020] [Accepted: 08/18/2020] [Indexed: 11/03/2022]
Abstract
OBJECTIVE Riboflavin transporter deficiencies (RTDs), involving SLC52A3 and SLC52A2 genes, have recently been related to Brown-Vialetto-Van Laere (BVVL) syndrome, a hereditary paediatric condition associating motor neuropathy (MN) and deafness. BVVL/RTD has rarely been reported in adult patients, but is probably underdiagnosed due to poor knowledge and lack of awareness of this form of disease among neurologists. In this study, we aimed to investigate the phenotype and prognosis of RTD patients with late-onset MN. METHODS We retrospectively collected clinical, biological and electrophysiological data from all French RTD patients with MN onset after 10 years of age (n=6) and extracted data from 19 other similar RTD patients from the literature. RESULTS Adult RTD patients with MN had heterogeneous clinical presentations, potentially mimicking amyotrophic lateral sclerosis or distal hereditary motor neuropathy (56%), multinevritis with cranial nerve involvement (16%), Guillain-Barré syndrome (8%) and mixed motor and sensory neuronopathy syndromes (20%, only in SLC52A2 patients). Deafness was often diagnosed before MN (in 44%), but in some patients, onset began only with MN (16%). The pattern of weakness varied widely, and the classic pontobulbar palsy described in BVVL was not constant. Biochemical tests were often normal. The majority of patients improved under riboflavin supplementation (86%). INTERPRETATION Whereas late-onset RTD may mimic different acquired or genetic causes of motor neuropathies, it is a diagnosis not to be missed since high-dose riboflavin per oral supplementation is often highly efficient.
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Affiliation(s)
- Christophe Carreau
- Department of Neurology, Reference Center for Lysosomal Diseases, Neuro-Metabolism Unit, AP-HP, Hôpital Universitaire Pitié Salpêtrière, Paris, France
| | - Charline Benoit
- Department of Neurology, AP-HP, Hôpital Universitaire Pitié Salpêtrière, Paris, France
| | - Guido Ahle
- Neurology, Hôpital Louis Pasteur, Colmar, Alsace, France
| | - Cécile Cauquil
- Neurology, Hôpital Bicêtre, Le Kremlin-Bicêtre, Île-de-France, France
| | - Agathe Roubertie
- Neuropediatrie, Hôpital Gui de Chauliac Pôle Neurosciences tête et cou, Montpellier, Languedoc-Roussillon Midi, France
| | - Timothée Lenglet
- Department of Neurophysiology, AP-HP, Hôpital Universitaire Pitié Salpêtrière, Paris, France
| | | | - Isabelle Meunier
- Ophthalmology, Hôpital Gui de Chauliac, Montpellier, Languedoc-Roussillon, France
| | - Alice Veauville-Merllié
- Laboratory of Inborn Errors of Metabolism, Hospices Civils de Lyon, Lyon, Auvergne-Rhône-Alpes, France
| | - Cécile Acquaviva-Bourdain
- Laboratory of Inborn Errors of Metabolism, Hospices Civils de Lyon, Lyon, Auvergne-Rhône-Alpes, France
| | - Yann Nadjar
- Department of Neurology, Reference Center for Lysosomal Diseases, Neuro-Metabolism Unit, AP-HP, Hôpital Universitaire Pitié Salpêtrière, Paris, France
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Sinha T, Naash MI, Al-Ubaidi MR. Flavins Act as a Critical Liaison Between Metabolic Homeostasis and Oxidative Stress in the Retina. Front Cell Dev Biol 2020; 8:861. [PMID: 32984341 PMCID: PMC7481326 DOI: 10.3389/fcell.2020.00861] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/10/2020] [Indexed: 12/14/2022] Open
Abstract
Derivatives of the vitamin riboflavin, FAD and FMN, are essential cofactors in a multitude of bio-energetic reactions, indispensable for lipid metabolism and also are requisites in mitigating oxidative stress. Given that a balance between all these processes contributes to the maintenance of retinal homeostasis, effective regulation of riboflavin levels in the retina is paramount. However, various genetic and dietary factors have brought to fore pathological conditions that co-occur with a suboptimal level of flavins in the retina. Our focus in this review is to, comprehensively summarize all the possible metabolic and oxidative reactions which have been implicated in various retinal pathologies and to highlight the contribution flavins may have played in these. Recent research has found a sensitive method of measuring flavins in both diseased and healthy retina, presence of a novel flavin binding protein exclusively expressed in the retina, and the presence of flavin specific transporters in both the inner and outer blood-retina barriers. In light of these exciting findings, it is even more imperative to shift our focus on how the retina regulates its flavin homeostasis and what happens when this is disrupted.
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Affiliation(s)
- Tirthankar Sinha
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Muayyad R Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
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Mitochondrial and Peroxisomal Alterations Contribute to Energy Dysmetabolism in Riboflavin Transporter Deficiency. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:6821247. [PMID: 32855765 PMCID: PMC7443020 DOI: 10.1155/2020/6821247] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/07/2020] [Accepted: 07/13/2020] [Indexed: 12/16/2022]
Abstract
Riboflavin transporter deficiency (RTD) is a childhood-onset neurodegenerative disorder characterized by progressive pontobulbar palsy, sensory and motor neuron degeneration, sensorineural hearing loss, and optic atrophy. As riboflavin (RF) is the precursor of FAD and FMN, we hypothesize that both mitochondrial and peroxisomal energy metabolism pathways involving flavoproteins could be directly affected in RTD, thus impacting cellular redox status. In the present work, we used induced pluripotent stem cells (iPSCs) from RTD patients to investigate morphofunctional features, focusing on mitochondrial and peroxisomal compartments. Using this model, we document the following RTD-associated alterations: (i) abnormal colony-forming ability and loss of cell-cell contacts, revealed by light, electron, and confocal microscopy, using tight junction marker ZO-1; (ii) mitochondrial ultrastructural abnormalities, involving shape, number, and intracellular distribution of the organelles, as assessed by focused ion beam/scanning electron microscopy (FIB/SEM); (iii) redox imbalance, with high levels of superoxide anion, as assessed by MitoSOX assay accompanied by abnormal mitochondrial polarization state, evaluated by JC-1 staining; (iv) altered immunofluorescence expression of antioxidant systems, namely, glutathione, superoxide dismutase 1 and 2, and catalase, as assessed by quantitatively evaluated confocal microscopy; and (v) peroxisomal downregulation, as demonstrated by levels and distribution of fatty acyl β-oxidation enzymes. RF supplementation results in amelioration of cell phenotype and rescue of redox status, which was associated to improved ultrastructural features of mitochondria, thus strongly supporting patient treatment with RF, to restore mitochondrial- and peroxisomal-related aspects of energy dysmetabolism and oxidative stress in RTD syndrome.
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Rabbani B, Bakhshandeh MK, Navaeifar MR, Abbaskhanian A, Soveizi M, Geravandpoor S, Mahdieh N. Brown-Vialetto-Van Laere syndrome and Fazio-Londe syndrome: A novel mutation and in silico analyses. J Clin Neurosci 2020; 72:342-349. [PMID: 31959559 DOI: 10.1016/j.jocn.2020.01.040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 01/05/2020] [Indexed: 10/25/2022]
Abstract
Brown-Vialetto-Van Laere syndrome, a rare neurological disorder is due to SLC52A3 mutations. Here, the SLC52A3 protein and its mutations are in silico structurally and functionally analyzed among all the reported patients and a novel mutation is also reported. After clinical evaluations, SLC52A3 gene was sequenced and segregation analysis of the mutations was also checked. A comprehensive search was performed on the reported mutations of SLC52A3 gene. In silico structural and functional analyses of the mutations and interactome analyses of the protein were done using available software tools. Mutations of 37 affected individuals were identified. Thirty three mutations were determined. c.502A > C was a novel variant that it was segregated within the family. One mutation (c.639C > G) was responsible for 12% of the mutations. Segregation analysis, secondary structure, functional prediction achieved for the novel mutation showed pathogenicity of this variant. BVVL is a very rare disorder; SLC52A3 mutations are distributed among different populations and there might be one frequent mutation in this gene. BVVL should be more considered in Iran. In addition to segregation analysis, computational analyses could accelerate understanding the extent of pathogenicity of the novel variants.
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Affiliation(s)
- Bahareh Rabbani
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran; Growth and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Kazem Bakhshandeh
- Department of Pediatrics, Faculty of Medicine, Tehran Medical sciences, Islamic Azad university,Tehran, Iran
| | - Mohammad Reza Navaeifar
- Pediatric Infectious Diseases Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Ali Abbaskhanian
- Pediatric Infectious Diseases Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Mahdieh Soveizi
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Shahpour Geravandpoor
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Nejat Mahdieh
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran; Growth and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran; Cardiogenetic Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran.
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Bamaga AK, Maamari RN, Culican SM, Shinawi M, Golumbek PT. Child Neurology: Brown-Vialetto-Van Laere syndrome: Dramatic visual recovery after delayed riboflavin therapy. Neurology 2019; 91:938-941. [PMID: 30420458 DOI: 10.1212/wnl.0000000000006498] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Ahmed K Bamaga
- From the Departments of Neurology (A.K.B., P.T.G.) and Ophthalmology and Visual Sciences (R.N.M., S.M.C.) and Division of Genetics and Genomic Medicine, Department of Pediatrics (M.S.), Washington University School of Medicine, St Louis, MO; and Department of Pediatrics (A.K.B.), King Abdulaziz University, Jeddah, Saudi Arabia.
| | - Robi N Maamari
- From the Departments of Neurology (A.K.B., P.T.G.) and Ophthalmology and Visual Sciences (R.N.M., S.M.C.) and Division of Genetics and Genomic Medicine, Department of Pediatrics (M.S.), Washington University School of Medicine, St Louis, MO; and Department of Pediatrics (A.K.B.), King Abdulaziz University, Jeddah, Saudi Arabia
| | - Susan M Culican
- From the Departments of Neurology (A.K.B., P.T.G.) and Ophthalmology and Visual Sciences (R.N.M., S.M.C.) and Division of Genetics and Genomic Medicine, Department of Pediatrics (M.S.), Washington University School of Medicine, St Louis, MO; and Department of Pediatrics (A.K.B.), King Abdulaziz University, Jeddah, Saudi Arabia
| | - Marwan Shinawi
- From the Departments of Neurology (A.K.B., P.T.G.) and Ophthalmology and Visual Sciences (R.N.M., S.M.C.) and Division of Genetics and Genomic Medicine, Department of Pediatrics (M.S.), Washington University School of Medicine, St Louis, MO; and Department of Pediatrics (A.K.B.), King Abdulaziz University, Jeddah, Saudi Arabia
| | - Paul T Golumbek
- From the Departments of Neurology (A.K.B., P.T.G.) and Ophthalmology and Visual Sciences (R.N.M., S.M.C.) and Division of Genetics and Genomic Medicine, Department of Pediatrics (M.S.), Washington University School of Medicine, St Louis, MO; and Department of Pediatrics (A.K.B.), King Abdulaziz University, Jeddah, Saudi Arabia
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O'Callaghan B, Bosch AM, Houlden H. An update on the genetics, clinical presentation, and pathomechanisms of human riboflavin transporter deficiency. J Inherit Metab Dis 2019; 42:598-607. [PMID: 30793323 DOI: 10.1002/jimd.12053] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/31/2018] [Indexed: 11/10/2022]
Abstract
Riboflavin transporter deficiency (RTD) is a rare neurological condition that encompasses the Brown-Vialetto-Van Laere and Fazio-Londe syndromes since the discovery of pathogenic mutations in the SLC52A2 and SLC52A3 genes that encode human riboflavin transporters RFVT2 and RFVT3. Patients present with a deteriorating progression of peripheral and cranial neuropathy that causes muscle weakness, vision loss, deafness, sensory ataxia, and respiratory compromise which when left untreated can be fatal. Considerable progress in the clinical and genetic diagnosis of RTDs has been made in recent years and has permitted the successful lifesaving treatment of many patients with high dose riboflavin supplementation. In this review, we first outline the importance of riboflavin and its efficient transmembrane transport in human physiology. Reports on 109 patients with a genetically confirmed diagnosis of RTD are then summarized in order to highlight commonly presenting clinical features and possible differences between patients with pathogenic SLC52A2 (RTD2) or SLC52A3 (RTD3) mutations. Finally, we focus attention on recent work with different models of RTD that have revealed possible pathomechanisms contributing to neurodegeneration in patients.
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Affiliation(s)
- Benjamin O'Callaghan
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Annet M Bosch
- Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Pediatric Metabolic Diseases, Amsterdam, The Netherlands
| | - Henry Houlden
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
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Fazio-Londe syndrome in siblings from India with different phenotypes. Brain Dev 2018; 40:582-586. [PMID: 29501408 DOI: 10.1016/j.braindev.2018.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 02/14/2018] [Accepted: 02/14/2018] [Indexed: 11/21/2022]
Abstract
BACKGROUND Fazio-Londe syndrome also called progressive bulbar palsy of childhood is a very rare motor neuron disease of pediatric age group characterized by progressive paralysis of lower cranial nerves. OBJECTIVE To describe Fazio-Londe syndrome in sibling with different phenotype. METHODS A 6 years old female child presented with inability to close eyes, difficulty in swallowing, respiratory muscle weakness and voice change since 5 yr of age. Examination showed lower motor neuron facial nerve palsy, absent gag reflex, tongue atrophy, fasciculation, limb wasting and exaggerated deep tendon reflexes. An 11 year old boy, elder sibling of the above child presented with similar complaints at 10 years of age, other than later onset and lack of respiratory problem. Genetic testing in both cases confirmed the diagnosis of Fazio-Londe Syndrome. CONCLUSION In any child who presents with progressive bulbar palsy with lower motor neuron facial palsy a diagnosis of Fazio-Londe Syndrome should be considered and family members should also be screened.
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Jaeger B, Bosch AM. Clinical presentation and outcome of riboflavin transporter deficiency: mini review after five years of experience. J Inherit Metab Dis 2016; 39:559-64. [PMID: 26973221 PMCID: PMC4920840 DOI: 10.1007/s10545-016-9924-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Revised: 02/18/2016] [Accepted: 02/19/2016] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Riboflavin (vitamin B2) is absorbed in the small intestine by the human riboflavin transporters RFVT1 and RFVT3. A third riboflavin transporter (RFVT2) is expressed in the brain. In 2010 it was demonstrated that mutations in the riboflavin transporter genes SLC52A2 (coding for RFVT2) and SLC52A3 (coding for RFVT3) cause a neurodegenerative disorder formerly known as Brown-Vialetto-Van Laere (BVVL) syndrome, now renamed to riboflavin transporter deficiency. Five years after the diagnosis of the first patient we performed a review of the literature to study the presentation, treatment and outcome of patients with a molecularly confirmed diagnosis of a riboflavin transporter deficiency. METHOD A search was performed in Medline, Pubmed using the search terms 'Brown-Vialetto-Van Laere syndrome' and 'riboflavin transporter' and articles were screened for case reports of patients with a molecular diagnosis of a riboflavin transporter deficiency. RESULTS Reports on a total of 70 patients with a molecular diagnosis of a RFVT2 or RTVT3 deficiency were retrieved. The riboflavin transporter deficiencies present with weakness, cranial nerve deficits including hearing loss, sensory symptoms including sensory ataxia, feeding difficulties and respiratory difficulties which are caused by a sensorimotor axonal neuropathy and cranial neuropathy. Biochemical abnormalities may be absent and the diagnosis can only be made or rejected by molecular analysis of all genes. Treatment with oral supplementation of riboflavin is lifesaving. Therefore, if a riboflavin transporter deficiency is suspected, treatment must be started immediately without first awaiting the results of molecular diagnostics.
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Affiliation(s)
- Bregje Jaeger
- />Department of Pediatric Neurology, Emma Children’s Hospital, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Annet M. Bosch
- />Department of Pediatrics, Emma Children’s Hospital, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
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