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Dreha-Kulaczewski S, Sahoo P, Preusse M, Gkalimani I, Dechent P, Helms G, Hofer S, Steinfeld R, Gärtner J. Folate receptor α deficiency - Myelin-sensitive MRI as a reliable biomarker to monitor the efficacy and long-term outcome of a new therapeutic approach. J Inherit Metab Dis 2024; 47:387-403. [PMID: 38200656 DOI: 10.1002/jimd.12713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/23/2023] [Accepted: 12/27/2023] [Indexed: 01/12/2024]
Abstract
Cerebral folate transport deficiency, caused by a genetic defect in folate receptor α, is a devastating neurometabolic disorder that, if untreated, leads to epileptic encephalopathy, psychomotor decline and hypomyelination. Currently, there are limited data on effective dosage and duration of treatment, though early diagnosis and therapy with folinic acid appears critical. The aim of this long-term study was to identify new therapeutic approaches and novel biomarkers for assessing efficacy, focusing on myelin-sensitive MRI. Clinical, biochemical, structural and quantitative MRI parameters of seven patients with genetically confirmed folate receptor α deficiency were acquired over 13 years. Multimodal MRI approaches comprised MR-spectroscopy (MRS), magnetization transfer (MTI) and diffusion tensor imaging (DTI) sequences. Patients started oral treatment immediately following diagnosis or in an interval of up to 2.5 years. Escalation to intravenous and intrathecal administration was performed in the absence of effects. Five patients improved, one with a presymptomatic start of therapy remained symptom-free, and one with inconsistent treatment deteriorated. While CSF 5-methyltetrahydrofolate and MRS parameters normalized immediately after therapy initiation, myelin-sensitive MTI and DTI measures correlated with gradual clinical improvement and ongoing myelination under therapy. Early initiation of treatment at sufficient doses, considering early intrathecal applications, is critical for favorable outcome. The majority of patients showed clinical improvements that correlated best with MTI parameters, allowing individualized monitoring of myelination recovery. Presymptomatic therapy seems to ensure normal development and warrants newborn screening. Furthermore, the quantitative parameters of myelin-sensitive MRI for therapy assessments can now be used for hypomyelination disorders in general.
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Affiliation(s)
- Steffi Dreha-Kulaczewski
- Division of Pediatric Neurology, Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, Göttingen, Germany
| | - Prativa Sahoo
- Division of Pediatric Neurology, Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, Göttingen, Germany
| | - Matthias Preusse
- Kinderkrankenhaus Amsterdamer Strasse, Klinik für Kinder- und Jugendmedizin, Köln, Germany
| | - Irini Gkalimani
- Division of Pediatric Neurology, Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, Göttingen, Germany
| | - Peter Dechent
- MR-Research in Neuroscience, Department of Cognitive Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Gunther Helms
- Medical Radiation Physics, Lund University, Lund, Sweden
| | - Sabine Hofer
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Robert Steinfeld
- Division of Pediatric Neurology, Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, Göttingen, Germany
| | - Jutta Gärtner
- Division of Pediatric Neurology, Department of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, Göttingen, Germany
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Boksha IS, Prokhorova TA, Tereshkina EB, Savushkina OK, Burbaeva GS. Differentiated Approach to Pharmacotherapy of Autism Spectrum Disorders: Biochemical Aspects. BIOCHEMISTRY (MOSCOW) 2023; 88:303-318. [PMID: 37076279 DOI: 10.1134/s0006297923030021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Autism Spectrum Disorders (ASD) are highly heterogeneous neurodevelopmental disorders caused by a complex interaction of numerous genetic and environmental factors and leading to deviations in the nervous system formation at the very early developmental stages. Currently, there are no accepted pharmacological treatments for the so-called core symptoms of ASD, such as social communication disorders and restricted and repetitive behavior patterns. Lack of knowledge about biological basis of ASD, absence of the clinically significant biochemical parameters reflecting abnormalities in the signaling cascades controlling the nervous system development and functioning, and lack of methods for selection of clinically and biologically homogeneous subgroups are considered as causes for the failure of clinical trials of ASD pharmacotherapy. This review considers the possibilities of applying differentiated clinical and biological approaches to the targeted search for ASD pharmacotherapy with emphasis on biochemical markers associated with ASD and attempts to stratify patients by biochemical parameters. The use of such approach as "the target-oriented therapy and assessment of the target status before and during the treatment to identify patients with a positive response to treatment" is discussed using the published results of clinical trials as examples. It is concluded that identification of biochemical parameters for selection of the distinct subgroups among the ASD patients requires research on large samples reflecting clinical and biological diversity of the patients with ASD, and use of unified approaches for such studies. An integrated approach, including clinical observation, clinical-psychological assessment of the patient behavior, study of medical history and description of individual molecular profiles should become a new strategy for stratifying patients with ASD for clinical pharmacotherapeutic trials, as well as for evaluating their efficiency.
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Cerebral folate transporter deficiency: a potentially treatable neurometabolic disorder. Acta Neurol Belg 2023; 123:121-127. [PMID: 34002331 DOI: 10.1007/s13760-021-01700-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/30/2021] [Indexed: 10/21/2022]
Abstract
Cerebral folate deficiency (CFD) syndrome is a rare treatable neurometabolic disorder with low levels of the active form of folaten in cerebrospinal fluid (CSF) arising from different causes such as FOLR1 gene mutations or autoantibodies against the folate receptor-alpha (FR) protein that can block folate transport across the choroid plexus. It is characterized by late infantile onset refractory seizures, ataxia, movement disorder, and unexplained global developmental delay. Here, we report a patient diagnosed with autistic spectrum disorder, followed by refractory myoclonic-atonic seizures, ataxia, and loss of motor skills over time. A homozygous missense (c.665A > G) mutation in FOLR1 gene and extremely low CSF 5-methyltetrahydrofolate level led to the diagnosis of CFD. Although she was initiated on combined oral and intravenous high doses of folinic acid treatment at 6 years of age, mild improvement was achieved in terms of epileptic seizures and motor skills. It is important that CFD should be kept in mind in cases with refractory myoclonic-atonic seizure and folinic acid treatment should be started as soon as possible.
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Akiyama T, Kuki I, Kim K, Yamamoto N, Yamada Y, Igarashi K, Ishihara T, Hatano Y, Kobayashi K. Folic acid inhibits 5-methyltetrahydrofolate transport across the blood-cerebrospinal fluid barrier: Clinical biochemical data from two cases. JIMD Rep 2022; 63:529-535. [PMID: 36341171 PMCID: PMC9626660 DOI: 10.1002/jmd2.12321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/24/2022] [Accepted: 07/26/2022] [Indexed: 11/25/2022] Open
Abstract
Objective The use of folic acid (FA) has been discouraged in cerebral folate deficiency (CFD) because, theoretically, it could inhibit the transport of 5-methyltetrahydrofolic acid (5MTHF) across the blood-cerebrospinal fluid (CSF) barrier. We present the clinical biochemical data of two cases with CFD to support this hypothesis. Methods We measured CSF and serum 5MTHF concentrations in a patient with Kearns-Sayre syndrome (KSS) and a patient homozygous for MTHFR C677T polymorphism before and during folate supplementation therapy. To evaluate these 5MTHF concentrations, we also analyzed CSF and serum samples in pediatric patients without folate supplementation. Results Both patients had low CSF 5MTHF before treatment and high-dose FA therapy did not normalize CSF 5MTHF. There was a dissociation between serum total folate and 5MTHF concentrations during FA therapy, which was considered to be due to the appearance of unmetabolized FA. The addition of folinic acid did not improve low CSF 5MTHF in the KSS patient and the cessation of FA resulted in the normalization of CSF 5MTHF. In the patient homozygous for MTHFR C677T, minimization of the FA dosage resulted in the normalization of CSF 5MTHF and an increased CSF-to-serum 5MTHF ratio. Conclusions Our data suggest that excess supplementation of FA impaired 5MTHF transport across the blood-CSF barrier. In the treatment of CFD, supplementation of folinic acid or 5MTHF (in cases of impaired 5MTHF synthesis) is preferred over the use of FA. The reference values of CSF 5MTHF concentration based on 600 pediatric cases were also provided.
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Affiliation(s)
- Tomoyuki Akiyama
- Department of Child NeurologyOkayama University HospitalOkayamaJapan
- Department of Child Neurology, Okayama University Graduate School of MedicineDentistry and Pharmaceutical SciencesOkayamaJapan
| | - Ichiro Kuki
- Department of Pediatric NeurologyOsaka City General HospitalOsakaJapan
| | - Kiyohiro Kim
- Department of Pediatric NeurologyOsaka City General HospitalOsakaJapan
- Department of Pediatric NeurologyHyogo Prefectural Amagasaki General Medical CenterHyogoJapan
| | - Naohiro Yamamoto
- Department of Pediatric NeurologyOsaka City General HospitalOsakaJapan
| | - Yumi Yamada
- Department of NeurologyNational Hospital Organization Nishiniigata Chuo HospitalNiigataJapan
- Department of Neurology, Brain Research InstituteNiigata UniversityNiigataJapan
| | - Kazuya Igarashi
- Department of NeurologyNational Hospital Organization Nishiniigata Chuo HospitalNiigataJapan
| | - Tomohiko Ishihara
- Department of Neurology, Brain Research InstituteNiigata UniversityNiigataJapan
| | - Yuya Hatano
- Department of Neurology, Brain Research InstituteNiigata UniversityNiigataJapan
| | - Katsuhiro Kobayashi
- Department of Child NeurologyOkayama University HospitalOkayamaJapan
- Department of Child Neurology, Okayama University Graduate School of MedicineDentistry and Pharmaceutical SciencesOkayamaJapan
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Folate Receptor Alpha Autoantibodies in Autism Spectrum Disorders: Diagnosis, Treatment and Prevention. J Pers Med 2021; 11:jpm11080710. [PMID: 34442354 PMCID: PMC8398778 DOI: 10.3390/jpm11080710] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 07/20/2021] [Accepted: 07/21/2021] [Indexed: 11/16/2022] Open
Abstract
Folate deficiency and folate receptor autoimmune disorder are major contributors to infertility, pregnancy related complications and abnormal fetal development including structural and functional abnormalities of the brain. Food fortification and prenatal folic acid supplementation has reduced the incidence of neural tube defect (NTD) pregnancies but is unlikely to prevent pregnancy-related complications in the presence of folate receptor autoantibodies (FRAb). In pregnancy, these autoantibodies can block folate transport to the fetus and in young children, folate transport to the brain. These antibodies are prevalent in neural tube defect pregnancies and in developmental disorders such as cerebral folate deficiency (CFD) syndrome and autism spectrum disorder (ASD). In the latter conditions, folinic acid treatment has shown clinical improvement in some of the core ASD deficits. Early testing for folate receptor autoantibodies and intervention is likely to result in a positive outcome. This review discusses the first identification of FRAb in women with a history of neural tube defect pregnancy and FRAb’s association with sub-fertility and preterm birth. Autoantibodies against folate receptor alpha (FRα) are present in about 70% of the children with a diagnosis of ASD, and a significant number of these children respond to oral folinic acid with overall improvements in speech, language and social interaction. The diagnosis of folate receptor autoimmune disorder by measuring autoantibodies against FRα in the serum provides a marker with the potential for treatment and perhaps preventing the pathologic consequences of folate receptor autoimmune disorder.
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Brunetti S, Malerba L, Giordano L, Parrini E, Guerrini R, Palumbo G, Parazzini C, Bestetti I, Accorsi P. Cerebral folate transporter deficiency syndrome in three siblings: Why genetic testing for developmental and epileptic encephalopathies should be performed early and include the FOLR1 gene. Am J Med Genet A 2021; 185:2526-2531. [PMID: 34008900 DOI: 10.1002/ajmg.a.62345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 04/05/2021] [Accepted: 04/16/2021] [Indexed: 11/08/2022]
Abstract
Cerebral folate transporter deficiency syndrome, caused by FOLR-1 mutations is characterized by late infantile onset, severe developmental regression, epilepsy, and leukodystrophy. An extremely low concentration of 5-methyltetrahydrofolate in the cerebrospinal fluid provides a crucial clue to its diagnosis and is a treatment target. Oral or intravenous folinic acid (5-formyltetrahydrofolate) administration improves clinical symptoms and brain magnetic resonance imaging (MRI) findings. We describe three siblings carrying a novel homozygous FOLR1 nonsense mutation, that were referred due to intractable epilepsy and progressive neurological decline. Brain MRI showed hypomyelination and cerebellar atrophy. Folinic acid (oral and intravenous) supplementation, initiated after over 15 years illness, has failed to result in any sizeable clinical or neurophysiological improvement. Cerebral folate transport deficiency bears overlapping clinical features with many severe developmental encephalopathies. It is crucial to recognize FOLR1 signs and establish an early clinical and molecular diagnosis in order to provide timely folinic acid treatment and improve outcome.
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Affiliation(s)
- Sara Brunetti
- Child and Adolescent Neurology and Psychiatry Unit, Children Hospital, ASST Spedali Civili of Brescia, Brescia, Italy
| | - Laura Malerba
- Child and Adolescent Neurology and Psychiatry Unit, Children Hospital, ASST Spedali Civili of Brescia, Brescia, Italy
| | - Lucio Giordano
- Child and Adolescent Neurology and Psychiatry Unit, Children Hospital, ASST Spedali Civili of Brescia, Brescia, Italy
| | - Elena Parrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Centre, A. Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Neuroscience Centre, A. Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Giovanni Palumbo
- Neuroradiology Department, University of Brescia, Brescia, Italy
| | - Cecilia Parazzini
- Pediatric radiology and neuroradiology Department, Children's Hospital V. Buzzi, Milan, Italy
| | - Ilaria Bestetti
- Research Laboratory of Medical Cytogenetics and Molecular Genetics, IRCCS Istituto Auxologico Italiano, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Patrizia Accorsi
- Child and Adolescent Neurology and Psychiatry Unit, Children Hospital, ASST Spedali Civili of Brescia, Brescia, Italy
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Sun H, Shen XR, Fang ZB, Jiang ZZ, Wei XJ, Wang ZY, Yu XF. Next-Generation Sequencing Technologies and Neurogenetic Diseases. Life (Basel) 2021; 11:life11040361. [PMID: 33921670 PMCID: PMC8072598 DOI: 10.3390/life11040361] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/05/2021] [Accepted: 04/16/2021] [Indexed: 12/18/2022] Open
Abstract
Next-generation sequencing (NGS) technology has led to great advances in understanding the causes of Mendelian and complex neurological diseases. Owing to the complexity of genetic diseases, the genetic factors contributing to many rare and common neurological diseases remain poorly understood. Selecting the correct genetic test based on cost-effectiveness, coverage area, and sequencing range can improve diagnosis, treatments, and prevention. Whole-exome sequencing and whole-genome sequencing are suitable methods for finding new mutations, and gene panels are suitable for exploring the roles of specific genes in neurogenetic diseases. Here, we provide an overview of the classifications, applications, advantages, and limitations of NGS in research on neurological diseases. We further provide examples of NGS-based explorations and insights of the genetic causes of neurogenetic diseases, including Charcot-Marie-Tooth disease, spinocerebellar ataxias, epilepsy, and multiple sclerosis. In addition, we focus on issues related to NGS-based analyses, including interpretations of variants of uncertain significance, de novo mutations, congenital genetic diseases with complex phenotypes, and single-molecule real-time approaches.
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Affiliation(s)
| | | | | | | | | | | | - Xue-Fan Yu
- Correspondence: ; Tel.: +86-157-5430-1836
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Gowda V, Natarajan B, Srinivasan V, Shivappa S. Treatable neurodegenerative disorder: Cerebral folate transport deficiency––two children from Southern India. J Pediatr Neurosci 2021; 16:273-276. [DOI: 10.4103/jpn.jpn_76_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/07/2020] [Indexed: 11/04/2022] Open
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Zhang C, Deng X, Wen Y, He F, Yin F, Peng J. First case report of cerebral folate deficiency caused by a novel mutation of FOLR1 gene in a Chinese patient. BMC MEDICAL GENETICS 2020; 21:235. [PMID: 33243190 PMCID: PMC7691102 DOI: 10.1186/s12881-020-01162-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/03/2020] [Indexed: 11/25/2022]
Abstract
Background Cerebral folate deficiency (CFD) is a neurological disease, hallmarked by remarkable low concentrations of 5-methyltetrahydrofolic acid (5-MTHF) in cerebrospinal fluid (CSF). The primary causes of CFD include the presence of folate receptor (FR) autoantibodies, defects of FR encoding gene FOLR1, mitochondrial diseases and congenital abnormalities in folate metabolism. Case presentation Here we first present a Chinese male CFD patient whose seizure onset at 2 years old with convulsive status epilepticus. Magnetic Resonance Imaging (MRI) revealed the development of encephalomalacia, laminar necrosis in multiple lobes of the brain and cerebellar atrophy. Whole Exome Sequencing (WES) uncovered a homozygous missense variant of c.524G > T (p.C175F) in FOLR1 gene. Further laboratory tests demonstrated the extremely low level of 5-MTHF in the CSF from this patient, which was attributed to cerebral folate transport deficiency. Following the intravenous and oral treatment of calcium folinate, the concentrations of 5-MTHF in CSF were recovered to the normal range and seizure symptoms were relieved as well. Conclusions One novel variation of FOLR1 was firstly identified from a Chinese male patient with tonic-clonic seizures, developmental delay, and ataxia. The WES and laboratory results elucidated the etiology of the symptoms. Clinical outcomes were improved by early diagnosis and proper treatment.
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Affiliation(s)
- Ciliu Zhang
- Xiangya Hospital Central South University, 87 Xiangya Road, Changsha, Hunan, 410008, P.R. China
| | - Xiaolu Deng
- Xiangya Hospital Central South University, 87 Xiangya Road, Changsha, Hunan, 410008, P.R. China
| | - Yafei Wen
- XiangYa School of Medicine of Central South University, 172 Tongzipo Road, Changsha, Hunan, 410013, P.R. China
| | - Fang He
- Xiangya Hospital Central South University, 87 Xiangya Road, Changsha, Hunan, 410008, P.R. China
| | - Fei Yin
- Xiangya Hospital Central South University, 87 Xiangya Road, Changsha, Hunan, 410008, P.R. China
| | - Jing Peng
- Xiangya Hospital Central South University, 87 Xiangya Road, Changsha, Hunan, 410008, P.R. China.
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Pope S, Artuch R, Heales S, Rahman S. Cerebral folate deficiency: Analytical tests and differential diagnosis. J Inherit Metab Dis 2019; 42:655-672. [PMID: 30916789 DOI: 10.1002/jimd.12092] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/19/2019] [Accepted: 03/25/2019] [Indexed: 11/07/2022]
Abstract
Cerebral folate deficiency is typically defined as a deficiency of the major folate species 5-methyltetrahydrofolate in the cerebrospinal fluid (CSF) in the presence of normal peripheral total folate levels. However, it should be noted that cerebral folate deficiency is also often used to describe conditions where CSF 5-MTHF is low, in the presence of low or undefined peripheral folate levels. Known defects of folate transport are deficiency of the proton coupled folate transporter, associated with systemic as well as cerebral folate deficiency, and deficiency of the folate receptor alpha, leading to an isolated cerebral folate deficiency associated with intractable seizures, developmental delay and/or regression, progressive ataxia and choreoathetoid movement disorders. Inborn errors of folate metabolism include deficiencies of the enzymes methylenetetrahydrofolate reductase, dihydrofolate reductase and 5,10-methenyltetrahydrofolate synthetase. Cerebral folate deficiency is potentially a treatable condition and so prompt recognition of these inborn errors and initiation of appropriate therapy is of paramount importance. Secondary cerebral folate deficiency may be observed in other inherited metabolic diseases, including disorders of the mitochondrial oxidative phosphorylation system, serine deficiency, and pyridoxine dependent epilepsy. Other secondary causes of cerebral folate deficiency include the effects of drugs, immune response activation, toxic insults and oxidative stress. This review describes the absorption, transport and metabolism of folate within the body; analytical methods to measure folate species in blood, plasma and CSF; inherited and acquired causes of cerebral folate deficiency; and possible treatment options in those patients found to have cerebral folate deficiency.
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Affiliation(s)
- Simon Pope
- Neurometabolic Unit, National Hospital for Neurology, London, UK
| | - Rafael Artuch
- Clinical Biochemistry Department, Institut de Recerca Sant Joan de Déu and CIBERER, ISCIII, Barcelona, Spain
| | - Simon Heales
- Neurometabolic Unit, National Hospital for Neurology, London, UK
- Department of Chemical Pathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
- Mitochondrial Research Group, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Shamima Rahman
- Mitochondrial Research Group, UCL Great Ormond Street Institute of Child Health, London, UK
- Department of Metabolic Medicine, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
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Tabassum S, AlAsmari A, AlSaman AA. Widening the phenotypic spectrum - Non epileptic presentation of folate transporter deficiency. J Clin Neurosci 2018; 59:341-344. [PMID: 30420205 DOI: 10.1016/j.jocn.2018.10.075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 10/15/2018] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Folate is essential for production of DNA, neurotransmitters and myelin and regulation of genetic activity. A specific transporter protein is required to transport folate from blood to CSF. Various inherited brain-specific folate transport defects have been recognized due to mutation in Folate Receptor alpha (FOLR1). FOLR1 mutation is one of the vitamin responsive encephalopathies and is inherited as an autosomal recessive condition. It has a wide spectrum of phenotype, commonly presenting as epileptic encephalopathy. Less frequently the condition may manifest with subtle hypotonia, movement disorder as tremors, ataxia or intellectual disability and autistic spectrum disorder. We present a case of folate transporter deficiency with non-epileptic manifestations, presenting with tremors, speech delay and stable white matter changes in MRI brain. OBJECTIVE We present a case of Folate transporter defect with Non-epileptic presentation. CONCLUSION Folate transporter deficiency has a wide range of presenting symptoms. Presentation with slowly progressive atypical symptoms, stable white matter changes in brain MRI that does not fit a specific diagnosis, should raise a high suspicion of FOLR1 mutation, even in absence of seizures. Since folate transporter deficiency is a treatable neurodegenerative disorder, early diagnosis and supplementation with folinic acid is vital.
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Affiliation(s)
- Sadia Tabassum
- National Neurosciences Institute, King Fahad Medical City, Riyadh, Saudi Arabia.
| | - Ali AlAsmari
- Department of Medical Genetics, King Fahad Medical City, Riyadh, Saudi Arabia
| | - Abdul Aziz AlSaman
- National Neurosciences Institute, King Fahad Medical City, Riyadh, Saudi Arabia
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Papandreou A, Rahman S, Fratter C, Ng J, Meyer E, Carr LJ, Champion M, Clarke A, Gissen P, Hemingway C, Hussain N, Jayawant S, King MD, Lynch BJ, Mewasingh L, Patel J, Prabhakar P, Neergheen V, Pope S, Heales SJR, Poulton J, Kurian MA. Spectrum of movement disorders and neurotransmitter abnormalities in paediatric POLG disease. J Inherit Metab Dis 2018; 41:1275-1283. [PMID: 30167885 PMCID: PMC6326959 DOI: 10.1007/s10545-018-0227-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/15/2018] [Accepted: 06/26/2018] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To describe the spectrum of movement disorders and cerebrospinal fluid (CSF) neurotransmitter profiles in paediatric patients with POLG disease. METHODS We identified children with genetically confirmed POLG disease, in whom CSF neurotransmitter analysis had been undertaken. Clinical data were collected retrospectively. CSF neurotransmitter levels were compared to both standardised age-related reference ranges and to non-POLG patients presenting with status epilepticus. RESULTS Forty-one patients with POLG disease were identified. Almost 50% of the patients had documented evidence of a movement disorder, including non-epileptic myoclonus, choreoathetosis and ataxia. CSF neurotransmitter analysis was undertaken in 15 cases and abnormalities were seen in the majority (87%) of cases tested. In many patients, distinctive patterns were evident, including raised neopterin, homovanillic acid and 5-hydroxyindoleacetic acid levels. CONCLUSIONS Children with POLG mutations can manifest with a wide spectrum of abnormal movements, which are often prominent features of the clinical syndrome. Underlying pathophysiology is probably multifactorial, and aberrant monoamine metabolism is likely to play a role.
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Affiliation(s)
- A Papandreou
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, 30 Guildford Street, London, WC1N 1EH, UK
- Department of Neurology, Great Ormond Street Hospital for Children, London, UK
- Genetics and Genomics Medicine Programme, UCL Great Ormond Street Institute of Child Health, London, UK
| | - S Rahman
- Mitochondrial Research Group, Genetics and Genomic Medicine Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Metabolic Department, Great Ormond Street Hospital for Children, London, UK
| | - C Fratter
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - J Ng
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, 30 Guildford Street, London, WC1N 1EH, UK
| | - E Meyer
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, 30 Guildford Street, London, WC1N 1EH, UK
| | - L J Carr
- Department of Neurology, Great Ormond Street Hospital for Children, London, UK
| | - M Champion
- Department of Inherited Metabolic Disease, Evelina London Children's Hospital, London, UK
| | - A Clarke
- Paediatric Neurology Department, St George's University Hospital, London, UK
| | - P Gissen
- Genetics and Genomics Medicine Programme, UCL Great Ormond Street Institute of Child Health, London, UK
- Metabolic Department, Great Ormond Street Hospital for Children, London, UK
- UCL-MRC Laboratory of Molecular Cell Biology, London, UK
| | - C Hemingway
- Department of Neurology, Great Ormond Street Hospital for Children, London, UK
| | - N Hussain
- Department of Paediatric Neurology, University Hospital of Leicester, Leicester, UK
| | - S Jayawant
- Department of Paediatric Neurology, John Radcliffe Hospital, Oxford, UK
| | - M D King
- Department of Paediatric Neurology and Clinical Neurophysiology, Children's University Hospital, Temple Street, Dublin, Ireland
| | - B J Lynch
- Department of Neurology and Clinical Neurophysiology, Children's University Hospital, Temple Street, Dublin, Ireland
| | - L Mewasingh
- Department of Paediatric Neurology, Imperial College Healthcare NHS Trust, London, UK
| | - J Patel
- Department of Paediatric Neurology, Bristol Royal Hospital for Children, Bristol, UK
| | - P Prabhakar
- Department of Neurology, Great Ormond Street Hospital for Children, London, UK
| | - V Neergheen
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | - S Pope
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | - S J R Heales
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
- Department of Paediatric Laboratory Medicine, Great Ormond Street Hospital for Children, London, UK
| | - J Poulton
- Nuffield Department of Women's and Reproductive Health, University of Oxford, The Women's Centre, Oxford, UK
| | - Manju A Kurian
- Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, 30 Guildford Street, London, WC1N 1EH, UK.
- Department of Neurology, Great Ormond Street Hospital for Children, London, UK.
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13
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Kleyner R, Malcolmson J, Tegay D, Ward K, Maughan A, Maughan G, Nelson L, Wang K, Robison R, Lyon GJ. KBG syndrome involving a single-nucleotide duplication in ANKRD11. Cold Spring Harb Mol Case Stud 2017; 2:a001131. [PMID: 27900361 PMCID: PMC5111005 DOI: 10.1101/mcs.a001131] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
KBG syndrome is a rare autosomal dominant genetic condition characterized by neurological involvement and distinct facial, hand, and skeletal features. More than 70 cases have been reported; however, it is likely that KBG syndrome is underdiagnosed because of lack of comprehensive characterization of the heterogeneous phenotypic features. We describe the clinical manifestations in a male currently 13 years of age, who exhibited symptoms including epilepsy, severe developmental delay, distinct facial features, and hand anomalies, without a positive genetic diagnosis. Subsequent exome sequencing identified a novel de novo heterozygous single base pair duplication (c.6015dupA) in ANKRD11, which was validated by Sanger sequencing. This single-nucleotide duplication is predicted to lead to a premature stop codon and loss of function in ANKRD11, thereby implicating it as contributing to the proband's symptoms and yielding a molecular diagnosis of KBG syndrome. Before molecular diagnosis, this syndrome was not recognized in the proband, as several key features of the disorder were mild and were not recognized by clinicians, further supporting the concept of variable expressivity in many disorders. Although a diagnosis of cerebral folate deficiency has also been given, its significance for the proband's condition remains uncertain.
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Affiliation(s)
- Robert Kleyner
- Stanley Institute for Cognitive Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Janet Malcolmson
- Stanley Institute for Cognitive Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA;; Genetic Counseling Graduate Program, Long Island University (LIU), Brookville, New York 11548, USA
| | - David Tegay
- Stanley Institute for Cognitive Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Kenneth Ward
- Affiliated Genetics, Inc., Salt Lake City, Utah 84109, USA
| | | | - Glenn Maughan
- KBG Syndrome Foundation, West Jordan, Utah 84088, USA
| | - Lesa Nelson
- Affiliated Genetics, Inc., Salt Lake City, Utah 84109, USA
| | - Kai Wang
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California 90089, USA;; Department of Psychiatry & Behavioral Sciences, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA;; Utah Foundation for Biomedical Research, Salt Lake City, Utah 84107, USA
| | - Reid Robison
- Utah Foundation for Biomedical Research, Salt Lake City, Utah 84107, USA
| | - Gholson J Lyon
- Stanley Institute for Cognitive Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA;; Utah Foundation for Biomedical Research, Salt Lake City, Utah 84107, USA
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14
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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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15
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Kobayashi Y, Tohyama J, Akiyama T, Magara S, Kawashima H, Akasaka N, Nakashima M, Saitsu H, Matsumoto N. Severe leukoencephalopathy with cortical involvement and peripheral neuropathy due to FOLR1 deficiency. Brain Dev 2017; 39:266-270. [PMID: 27743887 DOI: 10.1016/j.braindev.2016.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 09/22/2016] [Accepted: 09/25/2016] [Indexed: 11/24/2022]
Abstract
Cerebral folate deficiency due to folate receptor 1 gene (FOLR1) mutations is an autosomal recessive disorder resulting from a brain-specific folate transport defect. It is characterized by late infantile onset, severe psychomotor regression, epilepsy, and leukodystrophy. We describe a consanguineous girl exhibiting severe developmental regression, intractable epilepsy, polyneuropathy, and profound hypomyelination with cortical involvement. Magnetic resonance imaging showed cortical disturbances in addition to profound hypomyelination and cerebellar atrophy. Nerve conduction studies revealed both axonal degeneration and demyelinating features. A diagnosis of cerebral folate deficiency was confirmed by a homozygous c.466T>G (p.W156G) mutation in FOLR1, coupled with extremely low cerebrospinal fluid levels of 5-methyltetrahydrofolate. Her symptoms, neuroradiological findings, and polyneuropathy were alleviated by oral folinic acid treatment in conjunction with intravenous and intramuscular administration therapy. Our patient shows that folinic acid therapy can ameliorate the clinical symptoms, white matter disturbances, cortical insults, and peripheral neuropathy of cerebral folate deficiency caused by FOLR1 mutation. It is important to recognize these clinical symptoms and make a precise diagnosis early on, because cerebral folate deficiency is treatable.
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Affiliation(s)
- Yu Kobayashi
- Department of Child Neurology, Nishi-Niigata Chuo National Hospital, Japan.
| | - Jun Tohyama
- Department of Child Neurology, Nishi-Niigata Chuo National Hospital, Japan; Niigata University Medical and Dental Hospital, Japan
| | - Tomoyuki Akiyama
- Department of Child Neurology, Okayama University Hospital, Japan
| | - Shinichi Magara
- Department of Child Neurology, Nishi-Niigata Chuo National Hospital, Japan
| | - Hideshi Kawashima
- Department of Child Neurology, Nishi-Niigata Chuo National Hospital, Japan
| | - Noriyuki Akasaka
- Department of Child Neurology, Nishi-Niigata Chuo National Hospital, Japan
| | - Mitsuko Nakashima
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Japan
| | - Hirotomo Saitsu
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Japan
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16
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Karin I, Borggraefe I, Catarino CB, Kuhm C, Hoertnagel K, Biskup S, Opladen T, Blau N, Heinen F, Klopstock T. Folinic acid therapy in cerebral folate deficiency: marked improvement in an adult patient. J Neurol 2017; 264:578-582. [PMID: 28054128 DOI: 10.1007/s00415-016-8387-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 12/24/2016] [Accepted: 12/26/2016] [Indexed: 11/25/2022]
Affiliation(s)
- Ivan Karin
- Department of Neurology, Friedrich-Baur-Institute, University of Munich, Ziemssenstr. 1, 80336, Munich, Germany. .,German Network for Mitochondrial Disorders (mitoNET), Munich, Germany.
| | - Ingo Borggraefe
- Department of Pediatric Neurology, Developmental Medicine and Social Pediatrics, University of Munich, Munich, Germany
| | - Claudia B Catarino
- Department of Neurology, Friedrich-Baur-Institute, University of Munich, Ziemssenstr. 1, 80336, Munich, Germany.,German Network for Mitochondrial Disorders (mitoNET), Munich, Germany
| | - Christoph Kuhm
- Department of Neurology, Friedrich-Baur-Institute, University of Munich, Ziemssenstr. 1, 80336, Munich, Germany.,German Network for Mitochondrial Disorders (mitoNET), Munich, Germany
| | | | - Saskia Biskup
- CeGaT GmbH, Center for Genomics and Transcriptomics, Tübingen, Germany
| | - Thomas Opladen
- Division of Inborn Metabolic Diseases, University Children's Hospital, Heidelberg, Germany
| | - Nenad Blau
- Division of Inborn Metabolic Diseases, University Children's Hospital, Heidelberg, Germany
| | - Florian Heinen
- Department of Pediatric Neurology, Developmental Medicine and Social Pediatrics, University of Munich, Munich, Germany
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, University of Munich, Ziemssenstr. 1, 80336, Munich, Germany.,German Network for Mitochondrial Disorders (mitoNET), Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,DZNE-German Center for Neurodegenerative Diseases, Munich, Germany
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17
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Opladen T, Cortès-Saladelafont E, Mastrangelo M, Horvath G, Pons R, Lopez-Laso E, Fernández-Ramos JA, Honzik T, Pearson T, Friedman J, Scholl-Bürgi S, Wassenberg T, Jung-Klawitter S, Kuseyri O, Jeltsch K, Kurian MA, Garcia-Cazorla À. The International Working Group on Neurotransmitter related Disorders (iNTD): A worldwide research project focused on primary and secondary neurotransmitter disorders. Mol Genet Metab Rep 2016; 9:61-66. [PMID: 27830117 PMCID: PMC5094101 DOI: 10.1016/j.ymgmr.2016.09.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 09/29/2016] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Neurotransmitters are chemical messengers that enable communication between the neurons in the synaptic cleft. Inborn errors of neurotransmitter biosynthesis, breakdown and transport are a group of very rare neurometabolic diseases resulting in neurological impairment at any age from newborn to adulthood. METHODS AND RESULTS The International Working Group on Neurotransmitter related Disorders (iNTD) is the first international network focusing on the study of primary and secondary neurotransmitter disorders. It was founded with the aim to foster exchange and improve knowledge in the field of these rare diseases. The newly established iNTD patient registry for neurotransmitter related diseases collects longitudinal data on the natural disease course, approach to diagnosis, therapeutic strategies, and quality of life of affected patients. The registry forms the evidence base for the development of consensus guidelines for patients with neurotransmitter related disorders. CONCLUSION The iNTD network and registry will improve knowledge and strengthen research capacities in the field of inborn neurotransmitter disorders. The evidence-based guidelines will facilitate standardized diagnostic procedures and treatment approaches.
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Key Words
- 3-PGDH, 3-phosphoglycerat dehydrogenase
- 3-PGH, 3-phosphoglycerat dehydrogenase
- 3-PSP, 3-phosphoserine phosphatase
- 5-MTHF, 5-methyltetrahydrofolate
- AADC, aromatic l-amino acid decarboxylase
- AR/ADGTPCH, autosomal recessive/dominant GTP-cyclohydrolase deficiency
- BH4, tetrahydrobiopterin
- DAT, dopamine transporter
- DHFR, dihydrofolate reductase deficiency
- DHPR, dihydropteridine reductase
- Database
- Dopamine
- DßH, dopamine β-hydroxylase
- FOLR1, folate receptor alpha
- GABA
- GABA, gamma aminobutyric acid
- Glycine
- Guideline
- MAOA, monoamine oxidase A
- NKH, nonketotic hyperglycinemia
- NOS, nitric oxide synthase
- Network
- Neurotransmitter
- PAH, phenylalanine hydroxylase
- PSAT, phosphoserine aminotransferase
- PTPS, 6-pyruvoyl-tetrahydropterin synthase
- Patient registry
- SR, sepiapterin reductase
- SSADH, succinic semialdehyde dehydrogenase
- Serine
- Serotonin
- TH, tyrosine hydroxylase
- TPH, tryptophan hydroxylase
- VMAT, vesicular monoamine transporter
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Affiliation(s)
- Thomas Opladen
- Division of Child Neurology and Metabolic Diseases, University Children‘s Hospital Heidelberg, Germany
| | | | - Mario Mastrangelo
- Department of Pediatrics and Child Neuropsychiatry, Sapienza Università di Roma, Rome, Italy
| | - Gabriella Horvath
- Division of Biochemical Diseases, BC, Childrens Hospital, Vancouver, Canada
| | - Roser Pons
- First Department of Pediatrics, Pediatric Neurology Unit, Agia Sofia Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Eduardo Lopez-Laso
- Department of Pediatric Neurology, Reina Sofia University Hospital, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), University of Cordoba, CIBERER-ISCIII, Cordoba, Spain
| | - Joaquín A. Fernández-Ramos
- Department of Pediatric Neurology, Reina Sofia University Hospital, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), University of Cordoba, CIBERER-ISCIII, Cordoba, Spain
| | - Tomas Honzik
- Dep. of Pediatrics, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
| | - Toni Pearson
- Department of Neurology, Washington University School of Medicine, St. Louis, USA
| | - Jennifer Friedman
- Department of Neurosciences, University of California San Diego, Division of Neurology Rady Children's Hospital, Rady Children's Institute Genomic Medicine, San Diego, USA
| | - Sabine Scholl-Bürgi
- Department of Pediatrics I, Inherited Metabolic Disorders, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria
| | - Tessa Wassenberg
- Department of Neurology and Child Neurology, Radboudumc Nijmegen, Donders Institute of Brain Cognition and Behaviour, The Netherlands
| | - Sabine Jung-Klawitter
- Division of Child Neurology and Metabolic Diseases, University Children‘s Hospital Heidelberg, Germany
| | - Oya Kuseyri
- Division of Child Neurology and Metabolic Diseases, University Children‘s Hospital Heidelberg, Germany
| | - Kathrin Jeltsch
- Division of Child Neurology and Metabolic Diseases, University Children‘s Hospital Heidelberg, Germany
| | - Manju A. Kurian
- Developmental Neurosciences, UCL- Institute of Child Health and Department of Neurology, Great Ormond Street Hospital for Children NHS Foundations Trust, London, United Kingdom
| | - Àngels Garcia-Cazorla
- Department of Child Neurology, Neurometabolic Unit, CIBERER-ISCIII, Hospital Sant Joan de Déu Barcelona, Spain
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18
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Zhao R, Aluri S, Goldman ID. The proton-coupled folate transporter (PCFT-SLC46A1) and the syndrome of systemic and cerebral folate deficiency of infancy: Hereditary folate malabsorption. Mol Aspects Med 2016; 53:57-72. [PMID: 27664775 DOI: 10.1016/j.mam.2016.09.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/18/2016] [Indexed: 02/07/2023]
Abstract
The proton-coupled folate transporter (PCFT-SLC46A1) is the mechanism by which folates are absorbed across the brush-border membrane of the small intestine. The transporter is also expressed in the choroid plexus and is required for transport of folates into the cerebrospinal fluid. Loss of PCFT function, as occurs in the autosomal recessive disorder "hereditary folate malabsorption" (HFM), results in a syndrome characterized by severe systemic and cerebral folate deficiency. Folate-receptor alpha (FRα) is expressed in the choroid plexus, and loss of function of this protein, as also occurs in an autosomal recessive disorder, results solely in "cerebral folate deficiency" (CFD), the designation for this disorder. This paper reviews the current understanding of the functional and structural properties and regulation of PCFT, an electrogenic proton symporter, and contrasts PCFT properties with those of the reduced folate carrier (RFC), an organic anion antiporter, that is the major route of folate transport to systemic tissues. The clinical characteristics of HFM and its treatment, based upon the thirty-seven known cases with the clinical syndrome, of which thirty have been verified by genotype, are presented. The ways in which PCFT and FRα might interact at the level of the choroid plexus such that each is required for folate transport from blood to cerebrospinal fluid are considered along with the different clinical presentations of HFM and CFD.
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Affiliation(s)
- Rongbao Zhao
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Srinivas Aluri
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - I David Goldman
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA.
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19
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Delmelle F, Thöny B, Clapuyt P, Blau N, Nassogne MC. Neurological improvement following intravenous high-dose folinic acid for cerebral folate transporter deficiency caused by FOLR-1 mutation. Eur J Paediatr Neurol 2016; 20:709-13. [PMID: 27328863 DOI: 10.1016/j.ejpn.2016.05.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 03/25/2016] [Accepted: 05/31/2016] [Indexed: 02/09/2023]
Abstract
BACKGROUND Cerebral folate transporter deficiency caused by FOLR-1 mutations has been described in 2009. This condition is characterized by a 5MTHF level <5 nmol/l in the CSF, along with regression of acquisition in the second year of life, ataxia, and refractory myoclonic epilepsy. Oral or intravenous folinic acid (5-formyltetrahydrofolate) treatment has been shown to improve clinical status. CASE PRESENTATION We present the cases of two sisters with cerebral folate transport deficiency caused by mutation in the folate receptor 1 (FOLR1) gene (MIM *136430). Following recommendations, we administered oral folinic acid at 5 mg/kg/day, resulting in some initial clinical improvement, yet severe epilepsy persisted. During treatment, cerebrospinal fluid (CSF) analysis revealed normal 5-methyltetrahydrofolate (5MTHF) levels (60.1 nmol/l; normal range: 53-182 nmol/l). Epilepsy proved difficult to control and the younger patient exhibited neurological regression. We then administered high-dose folinic acid intravenously over 3 days (6 mg/kg/day for 24 h, then 12 mg/kg/day for 48 h), which significantly improved clinical status and epilepsy. CSF analysis revealed high 5MTHF levels following intravenous infusion (180 nmol/l). Treatment continued with monthly intravenous administrations of 20-25 mg/kg folinic acid. At 2 years post-treatment, clinical improvement was confirmed. CONCLUSIONS This report illustrates that cerebral folate transporter deficiency caused by FOLR-1 mutations is a treatable condition and can potentially be cured by folinic acid treatment. As already reported, early effective treatment is known to improve outcomes in affected children. In our study, intravenous high-dose folinic acid infusions appeared to optimize clinical response.
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Affiliation(s)
- Françoise Delmelle
- Université Catholique de Louvain, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Beat Thöny
- Division of Metabolism, University Children's Hospital, Zürich, Switzerland
| | - Philippe Clapuyt
- Université Catholique de Louvain, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Nenad Blau
- University Children's Hospital, Division of Inborn Metabolic Diseases, Department of General Pediatrics, Heidelberg, Germany
| | - Marie-Cécile Nassogne
- Université Catholique de Louvain, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
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20
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Pravenec M, Kožich V, Krijt J, Sokolová J, Zídek V, Landa V, Mlejnek P, Šilhavý J, Šimáková M, Škop V, Trnovská J, Kazdová L, Kajiya T, Wang J, Kurtz TW. Genetic Variation in Renal Expression ofFolate Receptor 1(Folr1) Gene Predisposes Spontaneously Hypertensive Rats to Metabolic Syndrome. Hypertension 2016; 67:335-41. [DOI: 10.1161/hypertensionaha.115.06158] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 11/18/2015] [Indexed: 01/30/2023]
Affiliation(s)
- Michal Pravenec
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Viktor Kožich
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Jakub Krijt
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Jitka Sokolová
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Václav Zídek
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Vladimír Landa
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Petr Mlejnek
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Jan Šilhavý
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Miroslava Šimáková
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Vojtěch Škop
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Jaroslava Trnovská
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Ludmila Kazdová
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Takashi Kajiya
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Jiaming Wang
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
| | - Theodore W. Kurtz
- From the Department of Model Diseases, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic (M.P., V.Z., V.L., P.M., J.Š., M.Š.); Institute of Inherited Metabolic Disorders, 1st Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic (V.K., J.K., J.Š.); Center of Experimental Medicine, Department of Metabolism and Diabetes, Institute for Clinical and Experimental Medicine, Prague, Czech Republic (V.Š., J.T., L.K.); and
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21
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Zhao R, Visentin M, Goldman ID. Determinants of the activities of antifolates delivered into cells by folate-receptor-mediated endocytosis. Cancer Chemother Pharmacol 2015; 75:1163-73. [PMID: 25847479 PMCID: PMC4442060 DOI: 10.1007/s00280-015-2733-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 03/23/2015] [Indexed: 12/14/2022]
Abstract
PURPOSE Elements in the endocytic process that are determinants of the activities of antifolates delivered by folate-receptor alpha (FRα) were explored. METHODS Antifolate growth inhibition was assessed with a 1- or 5-day exposure in reduced folate carrier-null HeLa cell lines that express a high level of FRα in the presence or absence of the proton-coupled folate transporter (PCFT). pH-dependent rates of dissociation from FRα were also determined. RESULTS With a 1-day drug exposure which is relevant to the pulse clinical administration of these drugs, FRα expression enhanced raltitrexed activity and modestly enhanced ZD9331 activity, but did not significantly augment the activity of pemetrexed or lomotrexol. With a 5-day drug exposure, FRα-mediated growth inhibition was increased for raltitrexed and ZD9331 and emerged for lomotrexol. While the FRα-augmented activity of lomotrexol and raltitrexed did not require PCFT, augmentation of ZD9331 activity required the co-expression of PCFT with both 1- and 5-day exposures. In contrast, there was no augmentation of pemetrexed activity by FRα under any condition. The activities of these agents correlated with their rate of dissociation from the receptor at acidic pH: raltitrexed > ZD9331 > lomotrexol > pemetrexed consistent with insufficient pemetrexed release from FRα for export from the endosomes. CONCLUSIONS FRα is unlikely to contribute to the pharmacological activity of antifolates, such as pemetrexed, that bind tightly to, and dissociate slowly from, the receptor particularly when the exposure time is brief. While PCFT was required for FRα-mediated ZD9931 activity, the activities of the other antifolates was independent of PCFT.
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Affiliation(s)
- Rongbao Zhao
- Departments of Medicine, Albert Einstein College of Medicine, Chanin 628, 1300 Morris Park Ave, Bronx, NY, 10461, USA,
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Sahoo BR, Maharana J, Patra MC, Bhoi GK, Lenka SK, Dubey PK, Goyal S, Dehury B, Pradhan SK. Structural and dynamic investigation of bovine folate receptor alpha (FOLR1), and role of ultra-high temperature processing on conformational and thermodynamic characteristics of FOLR1-folate complex. Colloids Surf B Biointerfaces 2014; 121:307-18. [PMID: 25023142 DOI: 10.1016/j.colsurfb.2014.05.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 04/12/2014] [Accepted: 05/17/2014] [Indexed: 01/12/2023]
Abstract
The folate receptor alpha (FOLR1) present in milk has widely been studied to investigate the effects of pasteurization, ultra-high temperature (UHT) processing and fermentation on net folate concentration. However, the folate binding mechanism with FOLR1, and effect of temperature on FOLR1-folate complex is poorly explored till now in bovine milk which is a chief resource of folate. Despite of enormous importance of folic acid and the routine intake of bovine milk, folic acid deficiency diseases are common in human race. To understand the folate deficiency in milk after processing, in absence of experimental structure, 3D model of bovine FOLR1 (bvFOLR1) was built followed by 40ns molecular dynamics (MD) simulation. The folate and its derivatives binding sites in bvFOLR1 were anticipated by molecular docking using AutoDock 4.2. Essential MD studies suggested the presence of a longer signal peptide (22 residues) and a short propeptide (7 residues) at the C-terminus that may cleaved during post-translational modification. MD analysis of bvFOLR1-folate complex at 298, 323, 353, 373 and 408K followed by binding energy (BE) calculation showed maximum binding affinity at ∼353K. However, at 373K and UHT (408K), the folate BE is significantly decreased with substantial conformational alteration. Heating at UHT followed by cooling within 298-408K range demoed no structural reformation with temperature reduction, and the folate was displaced from the active site. This study presented the disintegration of folate from bvFOLR1 during high temperature processing and revealed a lower folate concentration in UHT milk and dairy products.
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Affiliation(s)
- Bikash Ranjan Sahoo
- Department of Bioinformatics, Orissa University of Agriculture and Technology, Bhubaneswar, 751001, India; Laboratory of Molecular Biophysics, Institute for Protein Research, Osaka University, Osaka Prefecture, 5650871, Japan.
| | - Jitendra Maharana
- Department of Bioinformatics, Orissa University of Agriculture and Technology, Bhubaneswar, 751001, India; Biotechnology Laboratory, Central Inland Fisheries Research Institute, Barrackpore, Kolkata, West Bengal, 700120, India
| | - Mahesh Chandra Patra
- Department of Bioinformatics, Orissa University of Agriculture and Technology, Bhubaneswar, 751001, India; Animal Genomics Laboratory, Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, India
| | - Gopal Krushna Bhoi
- Department of Bioinformatics, Orissa University of Agriculture and Technology, Bhubaneswar, 751001, India
| | - Santosh Kumar Lenka
- Department of Bioinformatics, Orissa University of Agriculture and Technology, Bhubaneswar, 751001, India
| | - Praveen Kumar Dubey
- Immunology Frontier Research Centre, Osaka University, Osaka Prefecture, 5650871, Japan
| | - Shubham Goyal
- RIKEN Center for Life Science Technologies, Yokohama, 2300045, Japan
| | - Budheswar Dehury
- Department of Agricultural Biotechnology, Assam Agricultural University, Jorhat, 785013, Assam, India
| | - Sukanta Kumar Pradhan
- Department of Bioinformatics, Orissa University of Agriculture and Technology, Bhubaneswar, 751001, India
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Matherly LH, Wilson MR, Hou Z. The major facilitative folate transporters solute carrier 19A1 and solute carrier 46A1: biology and role in antifolate chemotherapy of cancer. Drug Metab Dispos 2014; 42:632-49. [PMID: 24396145 PMCID: PMC3965896 DOI: 10.1124/dmd.113.055723] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/06/2014] [Indexed: 01/19/2023] Open
Abstract
This review summarizes the biology of the major facilitative membrane transporters, the reduced folate carrier (RFC) (Solute Carrier 19A1) and the proton-coupled folate transporter (PCFT) (Solute Carrier 46A1). Folates are essential vitamins, and folate deficiency contributes to a variety of health disorders. RFC is ubiquitously expressed and is the major folate transporter in mammalian cells and tissues. PCFT mediates the intestinal absorption of dietary folates and appears to be important for transport of folates into the central nervous system. Clinically relevant antifolates for cancer, such as methotrexate and pralatrexate, are transported by RFC, and loss of RFC transport is an important mechanism of methotrexate resistance in cancer cell lines and in patients. PCFT is expressed in human tumors, and is active at pH conditions associated with the tumor microenvironment. Pemetrexed is an excellent substrate for both RFC and PCFT. Novel tumor-targeted antifolates related to pemetrexed with selective membrane transport by PCFT over RFC are being developed. In recent years, there have been major advances in understanding the structural and functional properties and the regulation of RFC and PCFT. The molecular bases for methotrexate resistance associated with loss of RFC transport and for hereditary folate malabsorption, attributable to mutant PCFT, were determined. Future studies should continue to translate molecular insights from basic studies of RFC and PCFT biology into new therapeutic strategies for cancer and other diseases.
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Affiliation(s)
- Larry H Matherly
- Department of Oncology (L.H.M., M.R.W., Z.H.) and Department of Pharmacology (L.H.M.), Wayne State University School of Medicine, Detroit, Michigan; and Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Detroit, Michigan (L.H.M., Z.H.)
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Zhao R, Diop-Bove N, Goldman ID. Enhanced receptor-mediated endocytosis and cytotoxicity of a folic acid-desacetylvinblastine monohydrazide conjugate in a pemetrexed-resistant cell line lacking folate-specific facilitative carriers but with increased folate receptor expression. Mol Pharmacol 2013; 85:310-21. [PMID: 24249723 DOI: 10.1124/mol.113.089110] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The reduced folate carrier (RFC), proton-coupled folate transporter (PCFT), and folate receptors (FR) are folate-specific transporters. Antifolates currently in the clinic, such as pemetrexed, methotrexate, and pralatrexate, are transported into tumor cells primarily via RFC. Folic acid conjugated to cytotoxics, a new class of antineoplastics, are transported into cells via FR-mediated endocytosis. To better define the role of PCFT in antifolate resistance, a methotrexate-resistant cell line, M160-8, was selected from a HeLa subline in which the RFC gene was deleted and PCFT was highly overexpressed. These cells were cross-resistant to pemetrexed. PCFT function and the PCFT mRNA level in M160-8 cells were barely detectable, and FR-α function and mRNA level were increased as compared with the parent cells. While pemetrexed rapidly associated with FR and was internalized within endosomes in M160-8 cells, consistent with FR-mediated transport, subsequent pemetrexed and (6S)-5-formyltetrahydrofolate export into the cytosol was markedly impaired. In contrast, M160-8 cells were collaterally sensitive to EC0905, a folic acid-desacetylvinblastine monohydrazide conjugate also transported by FR-mediated endocytosis. However, in this case a sulfhydryl bond is cleaved to release the lipophilic cytotoxic moiety into the endosome, which passively diffuses out of the endosome into the cytosol. Hence, resistance to pemetrexed in M160-8 cells was due to entrapment of the drug within the endosome due to the absence of PCFT under conditions in which the FR cycling function was intact.
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Affiliation(s)
- Rongbao Zhao
- Departments of Medicine (R.Z., I.D.G.) and Molecular Pharmacology (R.Z., N.D.-P., I.D.G.), Albert Einstein College of Medicine, Bronx, New York
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Petronella N, Drouin G. Purifying selection against gene conversions in the folate receptor genes of primates. Genomics 2013; 103:40-7. [PMID: 24184359 DOI: 10.1016/j.ygeno.2013.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/20/2013] [Accepted: 10/22/2013] [Indexed: 01/07/2023]
Abstract
We characterized the gene conversions between the human folate receptor (FOLR) genes and those of five other primate species. We found 26 gene conversions having an average length of 534 nucleotides. The length of these conversions is correlated with sequence similarity, converted regions have a higher GC-content and the average size of converted regions from a functional donor to another functional donor is significantly smaller than the average size from a functional donor to a pseudogene. Furthermore, the few conversions observed in the FOLR1 and FOLR2 genes did not change any amino acids in their coding regions and did not affect their promoter regions. In contrast, the promoter and coding regions of the FOLR3 gene are frequently converted and these conversions changed many amino acids in marmoset. These results suggest that purifying selection is limiting the functional impact that frequent gene conversions have on functional folate receptor genes.
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Affiliation(s)
- Nicholas Petronella
- Département de biologie et Centre de recherche avancée en génomique environnementale, Université d'Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Guy Drouin
- Département de biologie et Centre de recherche avancée en génomique environnementale, Université d'Ottawa, Ottawa, Ontario K1N 6N5, Canada.
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Zhao R, Goldman ID. Folate and thiamine transporters mediated by facilitative carriers (SLC19A1-3 and SLC46A1) and folate receptors. Mol Aspects Med 2013; 34:373-85. [PMID: 23506878 DOI: 10.1016/j.mam.2012.07.006] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 07/03/2012] [Indexed: 01/19/2023]
Abstract
The reduced folate carrier (RFC, SLC19A1), thiamine transporter-1 (ThTr1, SLC19A2) and thiamine transporter-2 (ThTr2, SLC19A3) evolved from the same family of solute carriers. SLC19A1 transports folates but not thiamine. SLC19A2 and SLC19A3 transport thiamine but not folates. SLC19A1 and SLC19A2 deliver their substrates to systemic tissues; SLC19A3 mediates intestinal thiamine absorption. The proton-coupled folate transporter (PCFT, SLC46A1) is the mechanism by which folates are absorbed across the apical-brush-border membrane of the proximal small intestine. Two folate receptors (FOLR1 and FOLR2) mediate folate transport across epithelia by an endocytic process. Folate transporters are routes of delivery of drugs for the treatment of cancer and inflammatory diseases. There are autosomal recessive disorders associated with mutations in genes encoded for SLC46A1 (hereditary folate malabsorption), FOLR1 (cerebral folate deficiency), SLC19A2 (thiamine-responsive megaloblastic anemia), and SLC19A3 (biotin-responsive basal ganglia disease).
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Affiliation(s)
- Rongbao Zhao
- Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Abstract
Seizures may be the first and the major presenting feature of an inborn error of metabolism (IEM), for example in a neonate with pyridoxine-dependent epilepsy. In other IEMs, seizures may be preceded by other major symptoms: by a reduced level of consciousness in a child with an organic acidaemia or urea cycle defect; or by loss of skills, progressive weakness, ataxia, and upper motor signs in a child with a lysosomal storage disorder or peroxisomal leukodystrophy. This review concentrates on those IEMs for which specific treatment is available. The common metabolic causes of seizures vary according to the age at presentation. Features from the history, examination, imaging, and first line biochemical investigations can all provide clues to an inborn error. This review attempts to delineate these and to provide a guide to the specific tests that can be used to make the diagnosis of disorders with specific treatment.
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Affiliation(s)
- Shamima Rahman
- Clinical and Molecular Genetics and Neurosciences Units, University College London Institute of Child Health, London and Metabolic and Neurosciences Units, Great Ormond Street Hospital for Children NHS Trust, London, UK.
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Kirsch SH, Herrmann W, Obeid R. Genetic defects in folate and cobalamin pathways affecting the brain. Clin Chem Lab Med 2013. [DOI: 10.1515/cclm-2012-0673] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Wang X, Cabrera RM, Li Y, Miller DS, Finnell RH. Functional regulation of P-glycoprotein at the blood-brain barrier in proton-coupled folate transporter (PCFT) mutant mice. FASEB J 2012; 27:1167-75. [PMID: 23212123 DOI: 10.1096/fj.12-218495] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Folate deficiency has been associated with many adverse clinical manifestations. The blood-brain barrier (BBB), formed by brain capillary endothelial cells, protects the brain from exposure to neurotoxicants. The function of BBB is modulated by multiple ABC transporters, particularly P-glycoprotein. A proton-coupled folate transporter (PCFT)-deficient mouse has been previously described as a model for systemic folate deficiency. Herein, we demonstrate that exposing mouse brain capillaries to the antiepileptic drug, valproic acid (VPA; 5 μM), significantly increased P-glycoprotein transport function in the wild-type animals. A ligand to the aryl hydrocarbon receptor, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), produced a similar induction of P-glycoprotein, which tightened the BBB, thereby increasing the neuroprotection. However, VPA- or TCDD-induced P-glycoprotein transport was blocked in the PCFT-nullizygous mice, indicating that multiple neuroprotective mechanisms are compromised under folate-deficient conditions. Brain capillaries from S-folinic acid (SFA; 40 mg/kg)-treated PCFT-nullizygous mice exhibited increased P-glycoprotein transport following VPA exposure. This suggests that SFA supplementation restored the normal BBB function. In addition, we show that tight-junction proteins are disintegrated in the PCFT mutant mice. Taken together, these findings strongly suggest that folate deficiency disrupts the BBB function by targeting the transporter and tight junctions, which may contribute to the development of neurological disorders.
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Affiliation(s)
- Xueqian Wang
- Department of Nutritional Sciences, Dell Pediatric Research Institute, The University of Texas at Austin, Austin, TX 78723, USA
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Steele SU, Cheah SM, Veerapandiyan A, Gallentine W, Smith EC, Mikati MA. Electroencephalographic and seizure manifestations in two patients with folate receptor autoimmune antibody-mediated primary cerebral folate deficiency. Epilepsy Behav 2012; 24:507-12. [PMID: 22749608 DOI: 10.1016/j.yebeh.2012.05.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 05/26/2012] [Accepted: 05/29/2012] [Indexed: 11/17/2022]
Abstract
Seizure semiology and electroencephalographic (EEG) manifestations of autoimmune-mediated cerebral folate deficiency (CFD) before and after therapy have yet to be fully characterized. Here, we report these findings in two such patients. Our first patient presented with the novel manifestation of infantile spasms at the age of 3months, while the second developed the previously reported initial onset of tonic seizures with static developmental delay, but subsequently manifested the novel finding of electrical status epilepticus in sleep at the age of 15years. Awareness of these new manifestations, together with the previously reported manifestations of developmental delay, seizure onset during the first 2years of life, occurrence of tonic, myoclonic-astatic, absence, and generalized tonic-clonic seizures, with an EEG of generalized spike-slow waves and multifocal spikes, is important to increase the index of suspicion of this treatable disorder.
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Affiliation(s)
- Sonya U Steele
- Division of Pediatric Neurology, Duke University Medical Center, Children's Health Center, 2301 Erwin Road, Durham, NC 27710, USA
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Watkins D, Rosenblatt DS. Update and new concepts in vitamin responsive disorders of folate transport and metabolism. J Inherit Metab Dis 2012; 35:665-70. [PMID: 22108709 DOI: 10.1007/s10545-011-9418-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 10/26/2011] [Accepted: 10/28/2011] [Indexed: 10/15/2022]
Abstract
Derivatives of folic acid are involved in transfer of one-carbon units in cellular metabolism, playing a role in synthesis of purines and thymidylate and in the remethylation of homocysteine to form methionine. Five inborn errors affecting folate transport and metabolism have been well studied: hereditary folate malabsorption, caused by mutations in the gene encoding the proton-coupled folate transporter (SLC46A1); glutamate formiminotransferase deficiency, caused by mutations in the FTCD gene; methylenetetrahydrofolate reductase deficiency, caused by mutations in the MTHFR gene; and functional methionine synthase deficiency, either as the result of mutations affecting methionine synthase itself (cblG, caused by mutations in the MTR gene) or affecting the accessory protein methionine synthase reductase (cblE, caused by mutations in the MTRR gene). Recently additional inborn errors have been identified. Cerebral folate deficiency is a clinically heterogeneous disorder, which in a few families is caused by mutations in the FOLR1 gene. Dihydrofolate reductase deficiency is characterized by megaloblastic anemia and cerebral folate deficiency, with variable neurological findings. It is caused by mutations in the DHFR gene. Deficiency in the trifunctional enzyme containing methylenetetrahydrofolate dehydrogenase, methenyltetrahydrofolate cyclohydrolase and formyltetrahydrofolate synthetase activities, has been identified in a single patient with megaloblastic anemia, atypical hemolytic uremic syndrome and severe combined immune deficiency. It is caused by mutations in the MTHFD1 gene.
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Affiliation(s)
- David Watkins
- The Hess B and Diane Finestone Laboratory in Memory of Jacob and Jenny Finestone, and Department of Human Genetics, McGill University Health Centre, 1650 Cedar Avenue, Room L3-319, Montreal, QC, Canada.
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Grapp M, Just IA, Linnankivi T, Wolf P, Lücke T, Häusler M, Gärtner J, Steinfeld R. Molecular characterization of folate receptor 1 mutations delineates cerebral folate transport deficiency. ACTA ACUST UNITED AC 2012; 135:2022-31. [PMID: 22586289 DOI: 10.1093/brain/aws122] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Cerebral folate transport deficiency is an inherited brain-specific folate transport defect that is caused by mutations in the folate receptor 1 gene coding for folate receptor alpha (FRα). This genetic defect gives rise to a progressive neurological disorder with late infantile onset. We screened 72 children with low 5-methyltetrahydrofolate concentrations in the cerebrospinal fluid and neurological symptoms that developed after infancy. We identified nucleotide alterations in the folate receptor 1 gene in 10 individuals who shared developmental regression, ataxia, profound cerebral hypomyelination and cerebellar atrophy. We found four novel pathogenic alleles, one splice mutation and three missense mutations. Heterologous expression of the missense mutations, including previously described mutants, revealed minor decrease in protein expression but loss of cell surface localization, mistargeting to intracellular compartments and thus absence of cellular binding of folic acid. These results explain the functional loss of folate receptor alpha for all detected folate receptor 1 mutations. Three individuals presenting a milder clinical phenotype revealed very similar biochemical and brain imaging data but partially shared pathogenic alleles with more severely affected patients. Thus, our studies suggest that different clinical severities do not necessarily correlate with residual function of folate receptor alpha mutants and indicate that additional factors contribute to the clinical phenotype in cerebral folate transport deficiency.
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Affiliation(s)
- M Grapp
- Department of Paediatrics and Paediatric Neurology, University Medical Centre Göttingen, Germany
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Zhao R, Diop-Bove N, Visentin M, Goldman ID. Mechanisms of membrane transport of folates into cells and across epithelia. Annu Rev Nutr 2011; 31:177-201. [PMID: 21568705 DOI: 10.1146/annurev-nutr-072610-145133] [Citation(s) in RCA: 241] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Until recently, the transport of folates into cells and across epithelia has been interpreted primarily within the context of two transporters with high affinity and specificity for folates, the reduced folate carrier and the folate receptors. However, there were discrepancies between the properties of these transporters and characteristics of folate transport in many tissues, most notably the intestinal absorption of folates, in terms of pH dependency and substrate specificity. With the recent cloning of the proton-coupled folate transporter (PCFT) and the demonstration that this transporter is mutated in hereditary folate malabsorption, an autosomal recessive disorder, the molecular basis for this low-pH transport activity is now understood. This review focuses on the properties of PCFT and briefly addresses the two other folate-specific transporters along with other facilitative and ATP-binding cassette (ABC) transporters with folate transport activities. The role of these transporters in the vectorial transport of folates across epithelia is considered.
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Affiliation(s)
- Rongbao Zhao
- Departments of Medicine and Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Dill P, Schneider J, Weber P, Trachsel D, Tekin M, Jakobs C, Thöny B, Blau N. Pyridoxal phosphate-responsive seizures in a patient with cerebral folate deficiency (CFD) and congenital deafness with labyrinthine aplasia, microtia and microdontia (LAMM). Mol Genet Metab 2011; 104:362-8. [PMID: 21752681 DOI: 10.1016/j.ymgme.2011.05.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2011] [Accepted: 05/30/2011] [Indexed: 12/21/2022]
Abstract
We present an 8-year-old boy with folate receptor alpha (FRα) defect and congenital deafness with labyrinthine aplasia, microtia and microdontia (LAMM syndrome). Both conditions are exceptionally rare autosomal recessive inherited diseases mapped to 11q13. Our patient was found to have novel homozygous nonsense mutations in the FOLR1 gene (p.R204X), and FGF3 gene (p.C50X). While the FRα defect is a disorder of brain-specific folate transport accompanied with cerebral folate deficiency (CFD) causing progressive neurological symptoms, LAMM syndrome is a solely malformative condition, with normal physical growth and cognitive development. Our patient presented with congenital deafness, hypotonia, dysphygia and ataxia in early childhood. At the age of 6 years he developed intractable epilepsy, and deteriorated clinically with respiratory arrest and severe hypercapnea at the age of 8 years. In contrast to the previously published patients with a FOLR1 gene defect, our patient presented with an abnormal l-dopa metabolism in CSF and high 3-O-methyl-dopa. Upon oral treatment with folinic acid the boy regained consciousness while the epilepsy could be successfully managed only with additional pyridoxal 5'-phosphate (PLP). This report pinpoints the importance of CSF folate investigations in children with unexplained progressive neurological presentations, even if a malformative syndrome is obviously present, and suggests a trial with PLP in folinic acid-unresponsive seizures.
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Affiliation(s)
- Patricia Dill
- Division of Pediatric Neurology and Developmental Medicine, University Children's Hospital, Basel, Switzerland.
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Mangold S, Blau N, Opladen T, Steinfeld R, Wessling B, Zerres K, Häusler M. Cerebral folate deficiency: a neurometabolic syndrome? Mol Genet Metab 2011; 104:369-72. [PMID: 21737328 DOI: 10.1016/j.ymgme.2011.06.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 06/07/2011] [Accepted: 06/07/2011] [Indexed: 11/19/2022]
Abstract
BACKGROUND Cerebral folate deficiency (CFD) is increasingly recognized in various neurological conditions, raising the question of whether it might represent a clear-cut clinical syndrome. METHODS Retrospective analysis of patients with low cerebral spinal fluid (CSF) 5-methyltetrahydrofolate (5MTHF) values was performed. RESULTS 58 pediatric patients with low (-2nd to -3rd standard deviation) and 45 patients with very low 5MTHF values (<3rd standard deviation) were identified, including 22 patients with defined underlying neurological conditions. The leading symptoms were mental retardation (n=84), motor retardation (n=75), epilepsy (n=53), ataxia (n=44) and pyramidal tract signs (n=37). There was no relationship between 5MTHF levels and the severity of clinical disease, the duration of clinical disease, distinct neurological symptoms and antiepileptic drug treatment, respectively. Genetical analysis for mutations in the folate receptor 1 gene proved normal in all 16 children studied. CONCLUSIONS For the majority of patients CFD is not a clear-cut neurometabolic syndrome but the common result of different genetic, metabolic or unknown processes. Nevertheless, CFD may represent a treatable disease-modifying factor which should therefore be addressed in prospective studies.
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Affiliation(s)
- Sarah Mangold
- Department of Pediatrics, University Hospital RWTH Aachen, Germany.
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Nilsson TK, Yngve A, Böttiger AK, Hurtig-Wennlöf A, Sjöström M. High folate intake is related to better academic achievement in Swedish adolescents. Pediatrics 2011; 128:e358-65. [PMID: 21746721 DOI: 10.1542/peds.2010-1481] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Adolescents are vulnerable to increased plasma total homocysteine (tHcy) and to insufficient folate status. Folate status and Hcy metabolism are linked to cognitive functions, but academic achievement by adolescents has not been studied in this respect. OBJECTIVE To assess a possible link between academic achievement in adolescents and tHcy and its determinants, dietary folate intake, MTHFR 677 TT homozygosity, and socioeconomic status (SES). SUBJECTS AND METHODS A study of 386 Swedish adolescents aged 15 years in whom plasma tHcy and MTHFR 677C →T genotype were assayed. The sum of school grades in 10 core subjects obtained in the final semester of compulsory 9 years of schooling was used as outcome measure of academic achievement. Lifestyle and SES data were obtained from questionnaires. RESULTS Academic achievement was strongly correlated to tertiles of tHcy (negatively; P = .023) and to tertiles of folate intake (positively; P < .001). Other significant predictors were gender, smoking, and SES (proxied by school, mother's education, and father's income). When these were controlled for, tertiles of folate intake (P < .002) but not tertiles of tHcy (P = .523) or MTHFR genotype remained significantly related to academic achievement. CONCLUSION Folate intake had a positive association with academic achievement in the 15-year-olds, which was not attenuated by SES or MTHFR 677 TT homozygosity. These results provide new information that points to the importance of keeping a closer watch on folate status in childhood and adolescence. They may also have direct implications for school meal provisions, school teaching programs, and information to parents.
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Cario H, Smith DE, Blom H, Blau N, Bode H, Holzmann K, Pannicke U, Hopfner KP, Rump EM, Ayric Z, Kohne E, Debatin KM, Smulders Y, Schwarz K. Dihydrofolate reductase deficiency due to a homozygous DHFR mutation causes megaloblastic anemia and cerebral folate deficiency leading to severe neurologic disease. Am J Hum Genet 2011; 88:226-31. [PMID: 21310277 DOI: 10.1016/j.ajhg.2011.01.007] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2010] [Revised: 01/13/2011] [Accepted: 01/17/2011] [Indexed: 11/27/2022] Open
Abstract
The importance of intracellular folate metabolism is illustrated by the severity of symptoms and complications caused by inborn disorders of folate metabolism or by folate deficiency. We examined three children of healthy, distantly related parents presenting with megaloblastic anemia and cerebral folate deficiency causing neurologic disease with atypical childhood absence epilepsy. Genome-wide homozygosity mapping revealed a candidate region on chromosome 5 including the dihydrofolate reductase (DHFR) locus. DHFR sequencing revealed a homozygous DHFR mutation, c.458A>T (p.Asp153Val), in all siblings. The patients' folate profile in red blood cells (RBC), plasma, and cerebrospinal fluid (CSF), analyzed by liquid chromatography tandem mass spectrometry, was compatible with DHFR deficiency. DHFR activity and fluorescein-labeled methotrexate (FMTX) binding were severely reduced in EBV-immortalized lymphoblastoid cells of all patients. Heterozygous cells displayed intermediate DHFR activity and FMTX binding. RT-PCR of DHFR mRNA revealed no differences between wild-type and DHFR mutation-carrying cells, whereas protein expression was reduced in cells with the DHFR mutation. Treatment with folinic acid resulted in the resolution of hematological abnormalities, normalization of CSF folate levels, and improvement of neurological symptoms. In conclusion, the homozygous DHFR mutation p.Asp153Val causes DHFR deficiency and leads to a complex hematological and neurological disease that can be successfully treated with folinic acid. DHFR is necessary for maintaining sufficient CSF and RBC folate levels, even in the presence of adequate nutritional folate supply and normal plasma folate.
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Pérez-Dueñas B, Toma C, Ormazábal A, Muchart J, Sanmartí F, Bombau G, Serrano M, García-Cazorla A, Cormand B, Artuch R. Progressive ataxia and myoclonic epilepsy in a patient with a homozygous mutation in the FOLR1 gene. J Inherit Metab Dis 2010; 33:795-802. [PMID: 20857335 DOI: 10.1007/s10545-010-9196-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 08/05/2010] [Accepted: 08/23/2010] [Indexed: 11/30/2022]
Abstract
Several unrelated disorders can lead to 5-methyltetrahydrofolate (5MTHF) depletion in the cerobrospinal fluid (CSF), including primary genetic disorders in folate-related pathways or those causing defective transport across the blood-CSF barrier. We report a case of cerebral folate transport deficiency due to a novel homozygous mutation in the FOLR1 gene, in an effort to clarify phenotype-genotype correlation in this newly identified neurometabolic disorder. A previously healthy infant developed an ataxic syndrome in the second year of life, followed by choreic movements and progressive myoclonic epilepsy. At the age of 26 months, we analyzed CSF 5MTHF by HPLC with fluorescence detection and conducted magnetic resonance (MR) imaging and spectroscopy studies. Finally, we performed mutational screening in the coding region of the FOLR1 gene. MR showed a diffuse abnormal signal of the cerebral white matter, cerebellar atrophy and a reduced peak of choline in spectroscopy. A profound deficiency of CSF 5MTHF (2 nmol/L; NV 48-127) with reduced CSF/plasma folate ratio (0.4; NV 1.5-3.5) was highly suggestive of defective brain folate-specific transport across the blood-CSF/brain barrier. Mutation screening of FOLR1 revealed a new homozygous missense mutation (p.Cys105Arg) that is predicted to abolish a disulfide bond, probably necessary for the correct folding of the protein. Both parents were heterozygous carriers of the same variant. Mutation screening in the FOLR1 gene is advisable in children with profound 5MTHF deficiency and decreased CSF/serum folate ratio. Progressive ataxia and myoclonic epilepsy, together with impaired brain myelination, are clinical hallmarks of the disease.
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Affiliation(s)
- Belén Pérez-Dueñas
- Departament of Neurology, Hospital Sant Joan de Déu, Passeig Sant Joan de Dèu, 2, 08950 Esplugues, Barcelona, Spain.
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Mahadeo K, Diop-Bove N, Shin D, Unal ES, Teo J, Zhao R, Chang MH, Fulterer A, Romero MF, Goldman ID. Properties of the Arg376 residue of the proton-coupled folate transporter (PCFT-SLC46A1) and a glutamine mutant causing hereditary folate malabsorption. Am J Physiol Cell Physiol 2010; 299:C1153-61. [PMID: 20686069 PMCID: PMC2980313 DOI: 10.1152/ajpcell.00113.2010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 08/03/2010] [Indexed: 01/19/2023]
Abstract
The proton-coupled folate transporter (PCFT-SLC46A1) is required for intestinal folate absorption and is mutated in the autosomal recessive disorder, hereditary folate malabsorption (HFM). This report characterizes properties and requirements of the R376 residue in PCFT function, including a R376Q mutant associated with HFM. Gln, Cys, and Ala substitutions resulted in markedly impaired transport of 5-formyltetrahydrofolate (5-FTHF) and 5-methyltetrahydrofolate (5-MTHF) due to an increase in K(m) and decrease in V(max) in HeLa R1-11 transfectants lacking endogenous folate transport function. In contrast, although the influx K(m) for pemetrexed was increased, transport was fully preserved at saturating concentrations and enhanced for the like-charged R376K- and R376H-PCFT. Pemetrexed and 5-FTHF influx mediated by R376Q-PCFT was markedly decreased at pH 5.5 compared with wild-type PCFT. However, while pemetrexed transport was substantially preserved at low pH (4.5-5.0), 5-FTHF transport remained very low. Electrophysiological studies in Xenopus oocytes demonstrated that 1) the R376Q mutant, like wild-type PCFT, transports protons in the absence of folate substrate, and in this respect has channel-like properties; and 2) the influx K(m) mediated by R376Q-PCFT is increased for 5-MTHF, 5-FTHF, and pemetrexed. The data suggest that mutation of the R376 residue to Gln impairs proton binding which, in turn, modulates the folate-binding pocket and depresses the rate of conformational alteration of the carrier, a change that appears to be, in part, substrate dependent.
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Affiliation(s)
- Kris Mahadeo
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Hyland K, Shoffner J, Heales SJ. Cerebral folate deficiency. J Inherit Metab Dis 2010; 33:563-70. [PMID: 20668945 DOI: 10.1007/s10545-010-9159-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 05/21/2010] [Accepted: 06/21/2010] [Indexed: 11/26/2022]
Abstract
Cerebral folate deficiency (CFD) is defined as any neurological syndrome associated with a low cerebrospinal fluid (CSF) concentration of 5-methyltetrahydrofolate (5MTHF) in the presence of normal peripheral folate status. CFD has a wide clinical presentation, with reported signs and symptoms generally beginning at around 4 months of age with irritability and sleep disturbances. These can be followed by psychomotor retardation, dyskinesia, cerebellar ataxia and spastic diplegia. Other signs may include deceleration of head growth, visual disturbances and sensorineural hearing loss. Identification of CFD is achieved by determining 5MTHF concentration in CSF. Once identified, CFD can in many cases be treated by administering oral folinic acid. Supplementation with folic acid is contraindicated and, if used, may exacerbate the CSF 5MTHF deficiency. Generation of autoantibodies against the folate receptor required to transport 5MTHF into CSF and mutations in the folate receptor 1 (FOLR1) gene have been reported to be causes of CFD. However, other mechanisms are probably also involved, as CFD has been reported in Aicardi-Goutiere's and Rett syndromes and in mitochondriopathies. Several metabolic conditions and a number of widely used drugs can also lead to a decrease in the concentration of CSF 5MTHF, and these should be considered in the differential diagnosis if a low concentration of 5MTHF is found following CSF analysis.
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Opladen T, Blau N, Ramaekers VT. Effect of antiepileptic drugs and reactive oxygen species on folate receptor 1 (FOLR1)-dependent 5-methyltetrahydrofolate transport. Mol Genet Metab 2010; 101:48-54. [PMID: 20619709 DOI: 10.1016/j.ymgme.2010.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 05/18/2010] [Accepted: 05/18/2010] [Indexed: 11/16/2022]
Abstract
Metabolic breakdown of valproate (VPA), carbamazepine (CBZ) and phenytoin (PHT) by the cytochrome P450 pathway generates toxic drug intermediates and reactive oxygen species (ROS). This mechanism has been suspected to play a role in the pathogenesis of secondary cerebral folate deficiency (CFD). Using KB-cell cultures, highly expressing the folate receptor 1 (FOLR1), the effect of antiepileptic drugs (AEDs) and reactive oxygen species (ROS) on the FOLR1 dependent 5-methyltetrahydrofolate (MTHF) uptake was studied. MTHF uptake is time and concentration dependent and shows saturation kinetics. At physiological MTHF concentrations the high-affinity FOLR1 represents the predominant mechanism for cellular incorporation, while at high MTHF concentrations other transport mechanisms participate in folate uptake. Exposure to PHT for more than 8h led to a higher MTHF uptake and decreased cell count, whereas MTHF uptake remained unaltered by VPA and CBZ. However, exposure to superoxide and hydrogen peroxide radicals significantly decreased cellular MTHF uptake. By specific elimination and downregulation of FOLR1 using phosphatidyl-inositol-specific phospholipase C (PIPLC) and siRNA silencing, it was shown that ROS not only inhibited FOLR1 mediated MTHF uptake but also affected all other mechanisms of membrane-mediated MTHF uptake. Generation of ROS with the use of AED might therefore provide an additional explanation for the disturbed folate transfer across the blood-CSF barrier in patients with CFD.
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Affiliation(s)
- Thomas Opladen
- University Children's Hospital Heidelberg, Division of Inborn Metabolic Diseases, Heidelberg, Germany
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Functional roles of aspartate residues of the proton-coupled folate transporter (PCFT-SLC46A1); a D156Y mutation causing hereditary folate malabsorption. Blood 2010; 116:5162-9. [PMID: 20805364 DOI: 10.1182/blood-2010-06-291237] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The proton-coupled folate transporter (PCFT; SLC46A1) mediates folate transport into enterocytes in the proximal small intestine; pcft loss-of-function mutations are the basis for hereditary folate malabsorption. The current study explored the roles of Asp residues in PCFT function. A novel, homozygous, loss-of-function mutation, D156Y, was identified in a child of Pakistani origin with hereditary folate malabsorption. Of the 6 other conserved Asp residues, only one, D109, is shown to be required for function. D156Y, along with a variety of other substitutions at this site (Trp, Phe, Val, Asn, or Lys), lacked function due to instability of the PCFT protein. Substantial function was preserved with Glu, Gly, and, to a lesser extent, with Ser, Thr, and Ala substitutions. This correlated with PCFT bio-tinylated at the cell surface. In contrast, all D109 mutants, including D109E, lacked function irrespective of pH (4.5, 5.5, and 7.4) or substrate concentration (0.5-100 μM), despite surface expression comparable to wild-type PCFT. Hence, D156 plays a critical role in PCFT protein stability, and D109, located in the first intracellular loop between the second and third transmembrane domains, is absolutely required for PCFT function.
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