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Shyam R, Sekhar Panda H, Mishra J, Jyoti Panda J, Kour A. Emerging biosensors in Phenylketonuria. Clin Chim Acta 2024; 559:119725. [PMID: 38734223 DOI: 10.1016/j.cca.2024.119725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 05/13/2024]
Abstract
Phenylketonuria (PKU) is an autosomal recessive metabolic disorder resulting from deficient phenylalanine hydroxylase (PAH) enzyme activity, leading to impaired phenylalanine (Phe) metabolism. This condition can lead to intellectual disability, epilepsy, and behavioural issues. Treatment typically involves strict dietary restrictions on natural protein intake, supplemented with chemically manufactured protein substitutes containing amino acids other than Phe. Various approaches, including casein glycomacropeptide (GMP), tetrahydrobiopterin (BH4), phenylalanine ammonia-lyase (PAL) therapy, large neutral amino acid (LNAA) supplementation, enzyme therapy, gene therapy, and medical therapies, aim to prevent Phe transport in the brain to potentially treat PKU. Although newborn screening programs and early dietary interventions have enhanced outcomes of the potential treatment strategies, limitations still persist in this direction. These involve potent accuracy concerns in diagnosis due to the existence of antibiotics in blood of PKU patients, affecting growth of the bacteria in the bacterial inhibition assay. Monitoring involves complex methods for instance, mass spectrometry and high-pressure liquid chromatography, which involve shortcomings such as lengthy protocols and the need for specialized equipment. To address these limitations, adaptable testing formats like bio/nano sensors are emerging with their cost-effectiveness, biodegradability, and rapid, accurate, and sensitive detection capabilities, offering promising alternatives for PKU diagnosis. This review provides insights into current treatment and diagnostic approaches, emphasizing on the potential applications of the diverse sensors intended for PKU diagnosis.
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Affiliation(s)
- Ritika Shyam
- University Institute of Pharma Sciences, Chandigarh University, Gharuan, Mohali, Punjab 140413, India
| | | | - Jibanananda Mishra
- School of Biosciences, RIMT University, Mandi Gobindgarh, Punjab 147301, India
| | - Jiban Jyoti Panda
- Institute of Nanoscience and Technology, Mohali, Punjab 140306, India.
| | - Avneet Kour
- University Institute of Pharma Sciences, Chandigarh University, Gharuan, Mohali, Punjab 140413, India.
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Upadia J, Crivelly K, Noh G, Cunningham A, Cerminaro C, Li Y, Mckoin M, Chenevert M, Andersson HC. Maximal dietary responsiveness after tetrahydrobiopterin (BH4) in 19 phenylalanine hydroxylase deficiency patients: What super-responders can expect. Mol Genet Metab Rep 2024; 38:101050. [PMID: 38469087 PMCID: PMC10926188 DOI: 10.1016/j.ymgmr.2024.101050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 03/13/2024] Open
Abstract
Background Inherited phenylalanine hydroxylase deficiency, also known as phenylketonuria (PKU), causes poor growth and neurologic deficits in the untreated state. After ascertainment through newborn screen and dietary phenylalanine (Phe) restriction to achieve plasma Phe in the range of 120-360 μmol/L, these disease manifestations can be prevented. Poor compliance with protein restricted diets supported by medical food is typical in later years, beginning in the late toddler and teenage years. Pharmacologic doses of oral tetrahydrobiopterin (BH4; sapropterin dihydrochloride) is effective in reducing plasma Phe in about 40-50% of PKU patients but effectiveness is highly variable. Objective To assess the maximal responsiveness to 20 mg/kg/day oral BH4 as it affects plasma Phe and dietary Phe allowance in PKU patients. Materials and methods This was a single-center, retrospective observational study, combining case reports of individual patients. We reported an outcome of 85 patients with PKU who were trialed on BH4. Phe levels and dietary records of 19 BH4 "super-responders" were analyzed. Results Overall, 63.5% of the patients (54/85) were considered BH4 responders. However, we quantitated the dietary liberalization of 19 of our responsive patients (35%), those with at least a 2-fold increase in dietary Phe and maintenance of plasma Phe in treatment range. In these "super-responders", the mean plasma Phe at baseline was 371 ± 237 μmol/L and decreased to 284 ± 273 μmol/L after 1 year on BH4. Mean dietary Phe tolerance increased significantly from 595 ± 256 to 2260 ± 1414 mg/day (p ≤0.0001), while maintaining mean plasma Phe levels within treatment range. Four patients no longer required dietary Phe restriction and could discontinue medical food. The majority of patients had at least one BH4-responsive genotype. Conclusion This cohort demonstrates the maximally achievable dietary liberalization which some PKU patients may expect with BH4 therapy. Health benefits are considered to accrue in patients with increased intact protein.
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Affiliation(s)
- Jariya Upadia
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Kea Crivelly
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Grace Noh
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Amy Cunningham
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Caroline Cerminaro
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Yuwen Li
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Meredith Mckoin
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Madeline Chenevert
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Hans C. Andersson
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
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Clark GC, Lai A, Agarwal A, Liu Z, Wang XY. Biopterin metabolism and nitric oxide recoupling in cancer. Front Oncol 2024; 13:1321326. [PMID: 38469569 PMCID: PMC10925643 DOI: 10.3389/fonc.2023.1321326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/26/2023] [Indexed: 03/13/2024] Open
Abstract
Tetrahydrobiopterin is a cofactor necessary for the activity of several enzymes, the most studied of which is nitric oxide synthase. The role of this cofactor-enzyme relationship in vascular biology is well established. Recently, tetrahydrobiopterin metabolism has received increasing attention in the field of cancer immunology and immunotherapy due to its involvement in the cytotoxic T cell response. Past research has demonstrated that when the availability of BH4 is low, as it is in chronic inflammatory conditions and tumors, electron transfer in the active site of nitric oxide synthase becomes uncoupled from the oxidation of arginine. This results in the production of radical species that are capable of a direct attack on tetrahydrobiopterin, further depleting its local availability. This feedforward loop may act like a molecular switch, reinforcing low tetrahydrobiopterin levels leading to altered NO signaling, restrained immune effector activity, and perpetual vascular inflammation within the tumor microenvironment. In this review, we discuss the evidence for this underappreciated mechanism in different aspects of tumor progression and therapeutic responses. Furthermore, we discuss the preclinical evidence supporting a clinical role for tetrahydrobiopterin supplementation to enhance immunotherapy and radiotherapy for solid tumors and the potential safety concerns.
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Affiliation(s)
- Gene Chatman Clark
- Department of Biochemistry, Virginia Commonwealth University, Richmond, VA, United States
- School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Alan Lai
- School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | | | - Zheng Liu
- Department of Human Molecular Genetics, Virginia Commonwealth University, Richmond, VA, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, United States
| | - Xiang-Yang Wang
- Department of Human Molecular Genetics, Virginia Commonwealth University, Richmond, VA, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, United States
- Institute of Molecular Medicine, Virginia Commonwealth University, Richmond, VA, United States
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Manti F, Caviglia S, Cazzorla C, Dicintio A, Pilotto A, Burlina AP. Expert opinion of an Italian working group on the assessment of cognitive, psychological, and neurological outcomes in pediatric, adolescent, and adult patients with phenylketonuria. Orphanet J Rare Dis 2022; 17:443. [PMID: 36544165 PMCID: PMC9769037 DOI: 10.1186/s13023-022-02488-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 08/15/2022] [Indexed: 12/24/2022] Open
Abstract
Phenylketonuria (PKU) is an inherited metabolic disease characterized by a defective conversion of phenylalanine (Phe) to tyrosine, potentially leading to Phe accumulation in the brain. Dietary restriction since birth has led to normal cognitive development. However, PKU patients can still develop cognitive or behavioral abnormalities and subtle neurological deficits. Despite the increasing evidence in the field, the assessment of neurocognitive, psychopathological, and neurological follow-up of PKU patients at different ages is still debated. The high interindividual variability in the cognitive outcome of PKU patients makes the specificity of the neurocognitive and behavioral assessment extremely challenging. In the present paper, a multidisciplinary panel of Italian PKU experts discussed different tools available for cognitive, psychopathological, and neurological assessment at different ages based on the existing literature and daily clinical practice. This study aims to provide evidence and a real-life-based framework for a specific clinical assessment of pediatric, adolescent, and adult patients affected by PKU.
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Affiliation(s)
- Filippo Manti
- grid.7841.aUnit of Child Neurology and Psychiatry, Department of Human Neuroscience, University of Rome La Sapienza, Rome, Italy
| | - Stefania Caviglia
- grid.414125.70000 0001 0727 6809Unit of Clinical Psychology, Department of Neurosciences, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Chiara Cazzorla
- grid.411474.30000 0004 1760 2630Division of Inborn Metabolic Diseases, Department of Pediatrics, University Hospital, Padua, Italy
| | - Annamaria Dicintio
- grid.488556.2Department of Metabolic Diseases and Clinical Genetics, Giovanni XXIII Children Hospital, Azienda Ospedaliero-Universitaria Consorziale Policlinico, 70126 Bari, Italy
| | - Andrea Pilotto
- grid.7637.50000000417571846Neurology Unit, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
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Lotz-Havla AS, Katzdobler S, Nuscher B, Weiß K, Levin J, Havla J, Maier EM. Serum glial fibrillary acidic protein and neurofilament light chain in patients with early treated phenylketonuria. Front Neurol 2022; 13:1011470. [PMID: 36247773 PMCID: PMC9559705 DOI: 10.3389/fneur.2022.1011470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 09/12/2022] [Indexed: 12/01/2022] Open
Abstract
To pave the way for healthy aging in early treated phenylketonuria (ETPKU) patients, a better understanding of the neurological course in this population is needed, requiring easy accessible biomarkers to monitor neurological disease progression in large cohorts. The objective of this pilot study was to investigate the potential of glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) as blood biomarkers to indicate changes of the central nervous system in ETPKU. In this single-center cross-sectional study, GFAP and NfL concentrations in serum were quantified using the Simoa® multiplex technology in 56 ETPKU patients aged 6–36 years and 16 age matched healthy controls. Correlation analysis and hierarchical linear regression analysis were performed to investigate an association with disease-related biochemical parameters and retinal layers assessed by optical coherence tomography. ETPKU patients did not show significantly higher GFAP concentrations (mean 73 pg/ml) compared to healthy controls (mean 60 pg/ml, p = 0.140). However, individual pediatric and adult ETPKU patients had GFAP concentrations above the healthy control range. In addition, there was a significant association of GFAP concentrations with current plasma tyrosine concentrations (r = −0.482, p = 0.036), a biochemical marker in phenylketonuria, and the retinal inner nuclear layer volume (r = 0.451, p = 0.04). There was no evidence of NfL alterations in our ETPKU cohort. These pilot results encourage multicenter longitudinal studies to further investigate serum GFAP as a complementary tool to better understand and monitor neurological disease progression in ETPKU. Follow-up investigations on aging ETPKU patients are required to elucidate the potential of serum NfL as biomarker.
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Affiliation(s)
- Amelie S. Lotz-Havla
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, LMU Munich, Munich, Germany
| | - Sabrina Katzdobler
- Department of Neurology, University Hospital, LMU Munich, Munich, Germany
| | - Brigitte Nuscher
- Department of Neurology, University Hospital, LMU Munich, Munich, Germany
| | - Katharina Weiß
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, LMU Munich, Munich, Germany
| | - Johannes Levin
- Department of Neurology, University Hospital, LMU Munich, Munich, Germany
- German Center for Neurodegenerative Diseases, site Munich, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Joachim Havla
- Institute of Clinical Neuroimmunology, University Hospital, LMU Munich, Munich, Germany
- Data Integration for Future Medicine (DIFUTURE) Consortium, LMU Munich, Munich, Germany
- *Correspondence: Joachim Havla
| | - Esther M. Maier
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, LMU Munich, Munich, Germany
- Esther M. Maier
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Evers RAF, van Wegberg AMJ, MacDonald A, Huijbregts SCJ, Leuzzi V, van Spronsen FJ. Dietary Liberalization in Tetrahydrobiopterin-Treated PKU Patients: Does It Improve Outcomes? Nutrients 2022; 14:nu14183874. [PMID: 36145250 PMCID: PMC9504284 DOI: 10.3390/nu14183874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 08/30/2022] [Accepted: 09/01/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose: this systematic review aimed to assess the effects of dietary liberalization following tetrahydrobiopterin (BH4) treatment on anthropometric measurements, nutritional biomarkers, quality of life, bone density, mental health and psychosocial functioning, and burden of care in PKU patients. Methods: the PubMed, Cochrane, and Embase databases were searched on 7 April 2022. We included studies that reported on the aforementioned domains before and after dietary liberalization as a result of BH4 treatment in PKU patients. Exclusion criteria were: studies written in a language other than English; studies that only included data of a BH4 loading test; insufficient data for the parameters of interest; and wrong publication type. Both within-subject and between-subject analyses were assessed, and meta-analyses were performed if possible. Results: twelve studies containing 14 cohorts and 228 patients were included. Single studies reported few significant differences. Two out of fifteen primary meta-analyses were significant; BMI was higher in BH4-treated patients versus controls (p = 0.02; standardized mean difference (SMD) (95% confidence interval (CI)) = −0.37 (−0.67, −0.06)), and blood cholesterol concentrations increased after starting BH4 treatment (p = 0.01; SMD (CI) = −0.70 (−1.26, −0.15)). Conclusion: there is no clear evidence that dietary liberalization after BH4 treatment has a positive effect on anthropometric measurements, nutritional biomarkers, or quality of life. No studies could be included for bone density, mental health and psychosocial functioning, and burden of care.
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Affiliation(s)
- Roeland A. F. Evers
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, 9700 RB Groningen, The Netherlands
| | - Annemiek M. J. van Wegberg
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, 9700 RB Groningen, The Netherlands
| | - Anita MacDonald
- Dietetic Department, Birmingham Children’s Hospital, Birmingham B4 6NH, UK
| | - Stephan C. J. Huijbregts
- Department of Clinical Child and Adolescent Studies-Neurodevelopmental Disorders, Faculty of Social Sciences, Leiden University, 2300 RB Leiden, The Netherlands
| | - Vincenzo Leuzzi
- Unit of Child Neurology and Psychiatry, Department of Human Neuroscience, Sapienza University of Rome, 00185 Rome, Italy
| | - Francjan J. van Spronsen
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, 9700 RB Groningen, The Netherlands
- Correspondence: ; Tel.: +31-(0)50-3614147
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Elhawary NA, AlJahdali IA, Abumansour IS, Elhawary EN, Gaboon N, Dandini M, Madkhali A, Alosaimi W, Alzahrani A, Aljohani F, Melibary EM, Kensara OA. Genetic etiology and clinical challenges of phenylketonuria. Hum Genomics 2022; 16:22. [PMID: 35854334 PMCID: PMC9295449 DOI: 10.1186/s40246-022-00398-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 07/08/2022] [Indexed: 02/08/2023] Open
Abstract
This review discusses the epidemiology, pathophysiology, genetic etiology, and management of phenylketonuria (PKU). PKU, an autosomal recessive disease, is an inborn error of phenylalanine (Phe) metabolism caused by pathogenic variants in the phenylalanine hydroxylase (PAH) gene. The prevalence of PKU varies widely among ethnicities and geographic regions, affecting approximately 1 in 24,000 individuals worldwide. Deficiency in the PAH enzyme or, in rare cases, the cofactor tetrahydrobiopterin results in high blood Phe concentrations, causing brain dysfunction. Untreated PKU, also known as PAH deficiency, results in severe and irreversible intellectual disability, epilepsy, behavioral disorders, and clinical features such as acquired microcephaly, seizures, psychological signs, and generalized hypopigmentation of skin (including hair and eyes). Severe phenotypes are classic PKU, and less severe forms of PAH deficiency are moderate PKU, mild PKU, mild hyperphenylalaninaemia (HPA), or benign HPA. Early diagnosis and intervention must start shortly after birth to prevent major cognitive and neurological effects. Dietary treatment, including natural protein restriction and Phe-free supplements, must be used to maintain blood Phe concentrations of 120-360 μmol/L throughout the life span. Additional treatments include the casein glycomacropeptide (GMP), which contains very limited aromatic amino acids and may improve immunological function, and large neutral amino acid (LNAA) supplementation to prevent plasma Phe transport into the brain. The synthetic BH4 analog, sapropterin hydrochloride (i.e., Kuvan®, BioMarin), is another potential treatment that activates residual PAH, thus decreasing Phe concentrations in the blood of PKU patients. Moreover, daily subcutaneous injection of pegylated Phe ammonia-lyase (i.e., pegvaliase; PALYNZIQ®, BioMarin) has promised gene therapy in recent clinical trials, and mRNA approaches are also being studied.
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Affiliation(s)
- Nasser A. Elhawary
- grid.412832.e0000 0000 9137 6644Department of Medical Genetics, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Imad A. AlJahdali
- grid.412832.e0000 0000 9137 6644Department of Community Medicine, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Iman S. Abumansour
- grid.412832.e0000 0000 9137 6644Department of Medical Genetics, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Ezzeldin N. Elhawary
- grid.123047.30000000103590315Faculty of Medicine, MS Genomic Medicine Program, University of Southampton, Southampton General Hospital, Southampton, UK
| | - Nagwa Gaboon
- grid.7269.a0000 0004 0621 1570Department of Clinical Genetics, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Mohammed Dandini
- Department of Laboratory and Blood Bank, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Abdulelah Madkhali
- grid.415254.30000 0004 1790 7311Department of Pathology and Laboratory Medicine, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
| | - Wafaa Alosaimi
- Department of Hematology, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Abdulmajeed Alzahrani
- Department of Laboratory and Blood Bank at Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Fawzia Aljohani
- Department of Pediatric Clinics, Maternity and Children Hospital, King Salman Medical City, Madinah, Saudi Arabia
| | - Ehab M. Melibary
- grid.412832.e0000 0000 9137 6644Department of Medical Genetics, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Osama A. Kensara
- grid.412832.e0000 0000 9137 6644Department of Clinical Nutrition, Faculty of Applied Medical Sciences, Umm Al-Qura University, Jeddah, Saudi Arabia
- Department of Biochemistry, Batterjee Medical College, Jeddah, Saudi Arabia
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Biasucci G, Brodosi L, Bettocchi I, Noto D, Pochiero F, Urban ML, Burlina A. The management of transitional care of patients affected by phenylketonuria in Italy: Review and expert opinion. Mol Genet Metab 2022; 136:94-100. [PMID: 35589496 DOI: 10.1016/j.ymgme.2022.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/21/2022] [Accepted: 04/21/2022] [Indexed: 12/24/2022]
Abstract
Phenylketonuria (PKU) is a metabolic inherited disorder in which transition from infancy to adult care is particularly difficult and not sufficiently regulated. According to the scientific literature, only few medical centers offer healthcare assistance for adult patients with PKU that are therefore still treated in pediatric settings. This generates psychological, emotional, and organizational discomfort among patients, leading them to discontinue the follow-up. European guidelines and national consensus documents underline this unmet need and the lack of practical recommendations for a structured transitional pathway in PKU. The aim of this review and expert opinion is to propose good practices for managing the transition period of PKU patients, based on the literature and the experience of a panel of Italian experts in PKU. The consensus of the experts was obtained through the administration of three rounds of surveys and one structured interview. The result is the first proposal of a pathway for an efficient transition of PKU patients. Key steps of the proposed pathway are the "a priori" planning involving the pediatric and adult teams, the acceptance of the patient and his/her family to the process, the preliminary definition of appropriate spaces in the structure, the organization of meetings with the joint team, and the appointment of a transition coordinator. For the first time, the involvement of decision makers and patient associations is proposed.
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Affiliation(s)
- Giacomo Biasucci
- Department of Paediatrics & Neonatology, Guglielmo da Saliceto Hospital, Via Taverna Giuseppe, 49, 29121 Piacenza, Italy
| | - Lucia Brodosi
- Department of Medical and Surgical Sciences, "Alma Mater" University, Sant'Orsola-Malpighi Hospital, Bologna, Italy.
| | - Ilaria Bettocchi
- Pediatric Unit, Department of Medical and Surgical Sciences, Regional Centre for Expanded Newborn Screening, S. Orsola-Malpighi University Hospital, Bologna, Italy
| | - Davide Noto
- Unit of Internal Medicine and Genetic Dyslipidemia, Azienda Ospedaliera Universitaria Policlinico "Paolo Giaccone" (University Hospital), Palermo, Italy
| | - Francesca Pochiero
- Metabolic and Muscular Unit, Neuroscience Department, Meyer Children's Hospital, Florence, Italy
| | - Maria Letizia Urban
- Department of Experimental and Clinical Medicine, University of Florence, Firenze, Italy
| | - Alberto Burlina
- Division of Inborn Metabolic Diseases, Department of Diagnostic Services, University Hospital of Padua, Via Orus 2B, 35129 Padua, Italy
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Çınar M, Kılıç Yıldırım G, Kocagil S, Çilingir O. Spectrum of PAH gene mutations and genotype-phenotype correlation in patients with phenylalanine hydroxylase deficiency from Turkey. J Pediatr Endocrinol Metab 2022; 35:639-647. [PMID: 35355500 DOI: 10.1515/jpem-2022-0047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/07/2022] [Indexed: 11/15/2022]
Abstract
OBJECTIVES The aim of our study was to define the genotype-phenotype correlations of mutations in the PAH gene among the Turkey's Central Anatolian region. METHODS Demographic characteristics of 108 patients with hyperphenylalaninemia (HPA) and 94 patients whose diagnosis was confirmed by PAH gene analysis (Sanger DNA Sequence Analysis and Next-Generation Sequencing) were determined retrospectively. Blood phenylalanine levels were analyzed using the high-performance liquid chromatography method. RESULTS Mild HPA-not-requiring-treatment (NT) was found in 50.9% of the patients, and a classical phenylketonuria (PKU) phenotype was found in 25.9%. Forty-seven types of variants were identified. The predominant variants were p.Ala403Val (9.9%), p.Ala300Ser (9.4%), and c.1066-11G>A (splicing) (9.4%). Missense mutations accounted for 68% of mutations and attenuated the clinical impact; splice variations were found in 14.8% of cases with severe features. The p.Thr380Met allele was specific to the mild HPA-NT group. The c.1066-11G>A (splicing) allele was associated with classical PKU, whereas the p.Arg408Trp allele was linked to severe symptoms. Three variations of unknown clinical significance were discovered: c.706+4A>T (splicing), c.843-5T>C (splicing), and p.Thr323=. Of these variants, the patient who was homozygous for the c.843-5T>C (splicing) allele related to the classical PKU phenotype. 70% of the patients who underwent tetrahydrobiopterin (BH4) test were responsive. Phenotypes that responded to BH4 treatment were mostly mild phenotypes. CONCLUSIONS The PAH genotype is the main factor that determines the phenotype of PKU. Establishing the relationship between the identified genetic mutations and phenotypic characteristics will provide very important data for each patient in terms of the specific management style.
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Affiliation(s)
- Müge Çınar
- Pediatrics, Bozüyük State Hospital, Bilecik, Turkey
| | - Gonca Kılıç Yıldırım
- Department of Paediatrics, Eskisehir Osmangazi University Faculty of Medicine, Division of Child Nutrition and Metabolism, Eskisehir, Turkey
- Eskisehir Osmangazi University Faculty of Medicine, Meselik Campuse, Odunpazari, Turkey
| | - Sinem Kocagil
- Eskisehir Osmangazi University Faculty of Medicine, Meselik Campuse, Odunpazari, Turkey
- Department of Genetics and Genomics Medicine, Eskisehir Osmangazi University Faculty of Medicine, Eskisehir, Turkey
| | - Oğuz Çilingir
- Eskisehir Osmangazi University Faculty of Medicine, Meselik Campuse, Odunpazari, Turkey
- Department of Genetics and Genomics Medicine, Eskisehir Osmangazi University Faculty of Medicine, Eskisehir, Turkey
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Lotz-Havla AS, Weiß K, Schiergens K, Regenauer-Vandewiele S, Parhofer KG, Christmann T, Böhm L, Havla J, Maier EM. Optical Coherence Tomography to Assess Neurodegeneration in Phenylalanine Hydroxylase Deficiency. Front Neurol 2021; 12:780624. [PMID: 34956063 PMCID: PMC8703042 DOI: 10.3389/fneur.2021.780624] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 11/02/2021] [Indexed: 11/13/2022] Open
Abstract
In phenylalanine hydroxylase (PAH) deficiency, an easily feasible method to access the progression of neurodegeneration is warranted to contribute to current discussions on treatment indications and targets. The objective of the present study was to investigate whether optical coherence tomography (OCT) measures as markers of neurodegeneration differ between patients with PAH deficiency and healthy controls (HCs) according to phenotype and metabolic control. In this single-center cross-sectional study, 92 patients with different phenotypes of PAH deficiency [PAH deficiency not requiring treatment, early treated phenylketonuria (ETPKU), and late-diagnosed phenylketonuria (PKU)] compared with 76 HCs were examined using spectral-domain OCT. Indices of phenylalanine elevation and variability were correlated with OCT parameters. Late-diagnosed PKU patients showed reduced peripapillary retinal nerve fiber layer (pRNFL) thickness and combined ganglion cell and inner plexiform layer (GCIPL) volume. Adult ETPKU patients were found to have lower GCIPL volume (p = 0.016), which correlated with the indices of phenylalanine control. In pediatric ETPKU patients with poor metabolic control, pRNFL was significantly reduced (p = 0.004). Patients with PAH deficiency not requiring treatment did not exhibit retinal degeneration. Inner nuclear layer (INL) was significantly increased in the pediatric ETPKU patients, driven by those with current poor metabolic control (p = 0.006). Our data provide evidence of retinal neuroaxonal degeneration and INL swelling, depending on the phenotype, current age, and metabolic control. These findings suggest that OCT is suitable to investigate neurodegeneration in PKU and we propose OCT as a sensitive, reliable, safe, low-burden, and low-cost examination for future multicenter studies.
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Affiliation(s)
- Amelie S Lotz-Havla
- Dr. von Hauner Children's Hospital, LMU University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Katharina Weiß
- Dr. von Hauner Children's Hospital, LMU University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Katharina Schiergens
- Dr. von Hauner Children's Hospital, LMU University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Klaus G Parhofer
- Medical Department IV - Grosshadern, LMU University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Tara Christmann
- Institute of Clinical Neuroimmunology, LMU University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Luise Böhm
- Institute of Clinical Neuroimmunology, LMU University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Joachim Havla
- Institute of Clinical Neuroimmunology, LMU University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany.,Data Integration for Future Medicine (DIFUTURE) Consortium, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Esther M Maier
- Dr. von Hauner Children's Hospital, LMU University Hospital, Ludwig-Maximilians-Universität München, Munich, Germany
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11
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Vela-Amieva M, Alcántara-Ortigoza MA, Ibarra-González I, González-del Angel A, Fernández-Hernández L, Guillén-López S, López-Mejía L, Carrillo-Nieto RI, Belmont-Martínez L, Fernández-Lainez C. An Updated PAH Mutational Spectrum of Phenylketonuria in Mexican Patients Attending a Single Center: Biochemical, Clinical-Genotyping Correlations. Genes (Basel) 2021; 12:genes12111676. [PMID: 34828281 PMCID: PMC8620669 DOI: 10.3390/genes12111676] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/18/2021] [Accepted: 10/19/2021] [Indexed: 11/21/2022] Open
Abstract
Establishing the genotypes of patients with hyperphenylalaninemia (HPA)/phenylketonuria (PKU, MIM#261600) has been considered a cornerstone for rational medical management. However, knowledge of the phenylalanine hydroxylase gene (PAH) mutational spectrum in Latin American populations is still limited. Herein, we aim to update the mutational PAH spectrum in the largest cohort of HPA/PKU Mexican patients (N = 124) reported to date. The biallelic PAH genotype was investigated by Sanger automated sequencing, and genotypes were correlated with documented biochemical phenotypes and theoretical tetrahydrobiopterin (BH4) responsiveness. Patients were biochemically classified as having classic PKU (50%, 62/124), mild PKU (20.2%, 25/124) and mild HPA (29.8%, 37/124). Furthermore, 78.2% of the included patients (97/124) were identified by newborn screening. A total of 60 different pathogenic variants were identified, including three novel ones (c. 23del, c. 625_626insC and c. 1315 + 5_1315 + 6insGTGTAACAG), the main categories being missense changes (58%, 35/60) and those affecting the catalytic domain (56.6%, 34/60), and c. 60 + 5G > T was the most frequent variant (14.5%, 36/248) mainly restricted (69.2%) to patients from the central and western parts of Mexico. These 60 types of variants constituted 100 different biallelic PAH genotypes, with the predominance of compound-heterozygous ones (96/124, 77%). The expected BH4 responsiveness based on the PAH genotype was estimated in 52% of patients (65/124), mainly due to the p. (Val388Met) (rs62516101) allele. Instead, our study identified 27 null variants with an allelic phenotype value of zero, with a predominance of c. 60 + 5G > T, which predicts the absence of BH4 responsiveness. An identical genotype reported in BIOPKUdb was found in 92/124 (74%) of our patients, leading to a genotype–phenotype concordance in 80/92 (86.9%) of them. The high number of variants found confirms the heterogeneous and complex mutational landscape of HPA/PKU in Mexico.
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Affiliation(s)
- Marcela Vela-Amieva
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.); (R.I.C.-N.); (L.B.-M.)
| | - Miguel Angel Alcántara-Ortigoza
- Laboratorio de Biología Molecular, Subdirección de Investigación Médica, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico; (M.A.A.-O.); (A.G.-d.A.); (L.F.-H.)
| | - Isabel Ibarra-González
- Unidad de Genética de la Nutrición, Instituto de Investigaciones Biomédicas, UNAM/Instituto Nacional de Pediatría, Ciudad de Mexico 04530, Mexico;
| | - Ariadna González-del Angel
- Laboratorio de Biología Molecular, Subdirección de Investigación Médica, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico; (M.A.A.-O.); (A.G.-d.A.); (L.F.-H.)
| | - Liliana Fernández-Hernández
- Laboratorio de Biología Molecular, Subdirección de Investigación Médica, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico; (M.A.A.-O.); (A.G.-d.A.); (L.F.-H.)
| | - Sara Guillén-López
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.); (R.I.C.-N.); (L.B.-M.)
| | - Lizbeth López-Mejía
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.); (R.I.C.-N.); (L.B.-M.)
| | - Rosa Itzel Carrillo-Nieto
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.); (R.I.C.-N.); (L.B.-M.)
| | - Leticia Belmont-Martínez
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.); (R.I.C.-N.); (L.B.-M.)
| | - Cynthia Fernández-Lainez
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de Mexico 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.); (R.I.C.-N.); (L.B.-M.)
- Correspondence: ; Tel.: +52-1-55-10840900 (ext. 1332)
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Lah M, McPheron M. Palynziq clinic: One year and 43 patients later. Mol Genet Metab 2021; 133:250-256. [PMID: 34074593 DOI: 10.1016/j.ymgme.2021.05.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/19/2021] [Accepted: 05/16/2021] [Indexed: 01/31/2023]
Abstract
Pegvaliase-pqpz (Palynziq) is an enzyme substitution therapy FDA approved May 2018 to treat phenylketonuria in adults with blood phenylalanine levels greater than 600 μmol/L (10 mg/dL). Pegvaliase is administered via subcutaneous injection and carries a high risk of side effects including anaphylaxis. A consensus statement on its use recommends careful education and monitoring of patients. We established a dedicated Palynziq Clinic in October 2018 with detailed protocols to minimize these risks. In the first year, we evaluated 43 patients, initiated Palynziq in 37 and transitioned two trial patients to commercial drug. 13/37 patients (35.1%) have sustained blood phenylalanine levels <360 μmol/L (6 mg/dL) without adjunct sapropterin dihydrochloride treatment or medical food. The timing and dosage needed to achieve a response did not correlate with patient weight, starting phenylalanine level, starting diet, or co-treatment with sapropterin dihydrochloride. Some patients had consistently low phenylalanine levels <30 μmol/L (0.5 mg/dL) and required doses as low as 20 mg weekly. Anaphylactic episodes were reported by 21.6% (8/37 patients) versus 10% seen in the clinical trial. Rates of other side effects were similar to or less than those in the trial. Adverse reactions commonly occurred shortly after dosage increases. We provide a model for safely introducing and managing pegvaliase in adult patients with PKU.
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Affiliation(s)
- Melissa Lah
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States of America.
| | - Molly McPheron
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States of America
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Gundorova P, Kuznetcova IA, Baydakova GV, Stepanova AA, Itkis YS, Kakaulina VS, Alferova IP, Lyazina LV, Andreeva LP, Kanivets I, Zakharova EY, Kutsev SI, Polyakov AV. BH4-deficient hyperphenylalaninemia in Russia. PLoS One 2021; 16:e0249608. [PMID: 33822819 PMCID: PMC8023510 DOI: 10.1371/journal.pone.0249608] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 03/22/2021] [Indexed: 02/07/2023] Open
Abstract
A timely detection of patients with tetrahydrobiopterin (BH4) -deficient types of hyperphenylalaninemia (HPABH4) is important for assignment of correct therapy, allowing to avoid complications. Often HPABH4 patients receive the same therapy as phenylalanine hydroxylase (PAH) -deficiency (phenylketonuria) patients—dietary treatment—and do not receive substitutive BH4 therapy until the diagnosis is confirmed by molecular genetic means. In this study, we present a cohort of 30 Russian patients with HPABH4 with detected variants in genes causing different types of HPA. Family diagnostics and biochemical urinary pterin spectrum analyses were carried out. HPABH4A is shown to be the prevalent type, 83.3% of all HPABH4 cases. The mutation spectrum for the PTS gene was defined, the most common variants in Russia were p.Thr106Met—32%, p.Asn72Lys—20%, p.Arg9His—8%, p.Ser32Gly—6%. We also detected 7 novel PTS variants and 3 novel QDPR variants. HPABH4 prevalence was estimated to be 0.5–0.9% of all HPA cases in Russia, which is significantly lower than in European countries on average, China, and Saudi Arabia. The results of this research show the necessity of introducing differential diagnostics for HPABH4 into neonatal screening practice.
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Affiliation(s)
| | | | | | | | | | - Victoria S. Kakaulina
- Federal State Budgetary Institution of Medical Department of Moscow “Morozov Children’s City Clinical Hospital of Medical Department of Moscow”, Moscow, Russia
| | - Irina P. Alferova
- Municipal Autonomous Health Care Institution of the Order of the Red Banner of Labor “Clinical Hospital № 1”, Chelyabinsk, Russia
| | - Lidya V. Lyazina
- Saint Petersburg State Public Health Institution "Medical Genetic Diagnostic Center”, Saint Petersburg, Russia
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Shintaku H, Ohura T, Takayanagi M, Kure S, Owada M, Matsubara Y, Yoshino M, Okano Y, Ito T, Okuyama T, Nakamura K, Matuo M, Endo F, Ida H. Guide for diagnosis and treatment of hyperphenylalaninemia. Pediatr Int 2021; 63:8-12. [PMID: 33423362 DOI: 10.1111/ped.14399] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 06/20/2020] [Accepted: 07/16/2020] [Indexed: 11/29/2022]
Abstract
IMPORTANCE Sapropterin hydrochloride, a natural coenzyme (6R-tetrahydrobiopterin) of phenylalanine hydroxylase, was first approved as a treatment for tetrahydrobiopterin deficiency in 1992 in Japan, and was then approved as a treatment for a tetrahydrobiopterin-responsive hyperphenylalaninemia in 2007 and 2008, in the USA and Japan, respectively. Guidelines are required on the proper use of sapropterin hydrochloride for tetrahydrobiopterin-responsive hyperphenylalaninemia. OBSERVATIONS It is recommended that tetrahydrobiopterin-responsive hyperphenylalaninemia should be diagnosed in all cases of hyperphenylalaninemia, including phenylketonuria, by tetrahydrobiopterin administration tests rather than by phenotype or blood phenylalanine levels. CONCLUSIONS AND RELEVANCE If tetrahydrobiopterin-responsive hyperphenylalaninemia is diagnosed, all ages can be treated with sapropterin hydrochloride. Although there are reports that sapropterin hydrochloride is effective and safe for the prevention of maternal phenylketonuria, further investigation is required.
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Affiliation(s)
- Haruo Shintaku
- Department of Pediatrics, Osaka City University Graduate School of Medicine, Osaka, Japan
| | | | - Masaki Takayanagi
- Department of Physical Therapy, Faculty of Health Care and Medical Sports, Teikyo Heisei University, Tokyo, Japan
| | - Shigeo Kure
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Misao Owada
- First Division on Special Formula, Imperial Gift Foundation Boshi Aiiku Kai, Tokyo, Japan
| | | | - Makoto Yoshino
- Laboratory of Gene Therapy and Regenerative Medicine, Cognitive and Molecular Research Institute of Brain Diseases, Kurume University, Fukuoka, Japan
| | | | - Tetsuya Ito
- Department of Pediatrics, Fujita Health University School of Medicine, Aichi, Japan
| | - Torayuki Okuyama
- Department of Clinical Laboratory Medicine, National Center for Child Health and Development, Tokyo, Japan
| | - Kimitoshi Nakamura
- Department of Pediatrics, Faculty of Life Science, Kumamoto University, Kumamoto, Japan
| | - Masafumi Matuo
- Graduate School of Rehabilitation, Kobe Gakuin University, Hyogo, Japan
| | - Fumio Endo
- Kumamoto Ezuko Medical Care Center, kumamoto, Japan
| | - Hiroyuki Ida
- Department of Pediatrics, The Jikei University, Tokyo, Japan
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15
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Phenylketonuria Diagnosis by Massive Parallel Sequencing and Genotype-Phenotype Association in Brazilian Patients. Genes (Basel) 2020; 12:genes12010020. [PMID: 33375644 PMCID: PMC7824641 DOI: 10.3390/genes12010020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 12/04/2022] Open
Abstract
Phenylketonuria (PKU) is a common inborn error of amino acid metabolism in which the enzyme phenylalanine hydroxylase, which converts phenylalanine to tyrosine, is functionally impaired due to pathogenic variants in the PAH gene. Thirty-four Brazilian patients with a biochemical diagnosis of PKU, from 33 unrelated families, were analyzed through next-generation sequencing in the Ion Torrent PGM™ platform. Phenotype–genotype correlations were made based on the BioPKU database. Three patients required additional Sanger sequencing analyses. Twenty-six different pathogenic variants were identified. The most frequent variants were c.1315+1G>A (n = 8/66), c.473G>A (n = 6/66), and c.1162G>A (n = 6/66). One novel variant, c.524C>G (p.Pro175Arg), was found in one allele and was predicted as likely pathogenic by the American College of Medical Genetics and Genomics (ACMG) criteria. The molecular modeling of p.Pro175Arg indicated that this substitution can affect monomers binding in the PAH tetramer, which could lead to a change in the stability and activity of this enzyme. Next-generation sequencing was a fast and effective method for diagnosing PKU and is useful for patient phenotype prediction and genetic counseling.
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Wiedemann A, Oussalah A, Jeannesson É, Guéant JL, Feillet F. [Phenylketonuria, from diet to gene therapy]. Med Sci (Paris) 2020; 36:725-734. [PMID: 32821049 DOI: 10.1051/medsci/2020127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The prognosis for phenylketonuria (PKU) has been improved by neonatal screening and dietary management via a low-phenylalanine diet. This treatment must be followed throughout life, which induces severe compliance problems. Drug treatment with sapropterin (or BH4) has come to help a reduced percentage of patients who respond to this drug. A subcutaneous enzyme therapy is available in the USA and has obtained European marketing authorization, but generates significant side effects, which limits its effectiveness. New therapeutic options for PKU are currently being developed, in particular gene therapy. The purpose of this article is to take stock of the pathophysiology and the various new therapeutic modalities currently in development.
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Affiliation(s)
- Arnaud Wiedemann
- Centre de référence des maladies métaboliques, Service de pédiatrie, CHRU de Nancy, 54000 Nancy, France - Inserm UMR_S 1256 (NGERE, Nutrition Génétique et Exposition aux Risques Environnementaux), Faculté de médecine de Nancy, Université de Lorraine, 54000 Nancy, France
| | - Abderrahim Oussalah
- Inserm UMR_S 1256 (NGERE, Nutrition Génétique et Exposition aux Risques Environnementaux), Faculté de médecine de Nancy, Université de Lorraine, 54000 Nancy, France - Département de médecine moléculaire, Laboratoire de biochimie et de biologie moléculaire nutrition, CHRU de Nancy, 54000 France
| | - Élise Jeannesson
- Inserm UMR_S 1256 (NGERE, Nutrition Génétique et Exposition aux Risques Environnementaux), Faculté de médecine de Nancy, Université de Lorraine, 54000 Nancy, France - Département de médecine moléculaire, Laboratoire de biochimie et de biologie moléculaire nutrition, CHRU de Nancy, 54000 France
| | - Jean-Louis Guéant
- Inserm UMR_S 1256 (NGERE, Nutrition Génétique et Exposition aux Risques Environnementaux), Faculté de médecine de Nancy, Université de Lorraine, 54000 Nancy, France - Département de médecine moléculaire, Laboratoire de biochimie et de biologie moléculaire nutrition, CHRU de Nancy, 54000 France
| | - François Feillet
- Centre de référence des maladies métaboliques, Service de pédiatrie, CHRU de Nancy, 54000 Nancy, France - Inserm UMR_S 1256 (NGERE, Nutrition Génétique et Exposition aux Risques Environnementaux), Faculté de médecine de Nancy, Université de Lorraine, 54000 Nancy, France
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Tran ML, Génisson Y, Ballereau S, Dehoux C. Second-Generation Pharmacological Chaperones: Beyond Inhibitors. Molecules 2020; 25:molecules25143145. [PMID: 32660097 PMCID: PMC7397201 DOI: 10.3390/molecules25143145] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/29/2020] [Accepted: 07/05/2020] [Indexed: 02/06/2023] Open
Abstract
Protein misfolding induced by missense mutations is the source of hundreds of conformational diseases. The cell quality control may eliminate nascent misfolded proteins, such as enzymes, and a pathological loss-of-function may result from their early degradation. Since the proof of concept in the 2000s, the bioinspired pharmacological chaperone therapy became a relevant low-molecular-weight compound strategy against conformational diseases. The first-generation pharmacological chaperones were competitive inhibitors of mutant enzymes. Counterintuitively, in binding to the active site, these inhibitors stabilize the proper folding of the mutated protein and partially rescue its cellular function. The main limitation of the first-generation pharmacological chaperones lies in the balance between enzyme activity enhancement and inhibition. Recent research efforts were directed towards the development of promising second-generation pharmacological chaperones. These non-inhibitory ligands, targeting previously unknown binding pockets, limit the risk of adverse enzymatic inhibition. Their pharmacophore identification is however challenging and likely requires a massive screening-based approach. This review focuses on second-generation chaperones designed to restore the cellular activity of misfolded enzymes. It intends to highlight, for a selected set of rare inherited metabolic disorders, the strategies implemented to identify and develop these pharmacologically relevant small organic molecules as potential drug candidates.
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Affiliation(s)
| | | | | | - Cécile Dehoux
- Correspondence: (S.B.); (C.D.); Tel.: +33-5-6155-6127 (C.D.)
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18
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Scudellaro E, Tartaglione L, Varriale F, Dell’Aversano C, Taglialatela-Scafati O. HPLC-Based Analysis of Impurities in Sapropterin Branded and Generic Tablets. Pharmaceutics 2020; 12:pharmaceutics12040323. [PMID: 32260076 PMCID: PMC7237990 DOI: 10.3390/pharmaceutics12040323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/31/2020] [Accepted: 03/31/2020] [Indexed: 11/20/2022] Open
Abstract
This work was aimed at the definition of a chromatographic method able to separate and quantify impurities present in sapropterin-containing drugs during an accelerated stability study. The chromatographic method was applied to the orphan drug Kuvan® and to its corresponding generic sapropterin Dipharma (Diterin®), both of which are approved for the treatment of hyperphenylalaninemia-induced symptoms. The two products tested had a similar manufacture date and both had an approved stability shelf-life of three years. Samples were analyzed by HPLC at T = 0 and after six months of storage at 40 °C and 75% relative humidity. Identification of the impurities was supported by a detailed mass spectrometry and MS/MS profile. The analysis demonstrated an overall higher stability for the Diterin® formulation, which was related to a lower increase of some impurities compared to Kuvan®.
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van Wegberg AMJ, Evers RAF, van Dam E, de Vries MC, Janssen MCH, Heiner-Fokkema MR, van Spronsen FJ. Does the 48-hour BH4 loading test miss responsive PKU patients? Mol Genet Metab 2020; 129:186-192. [PMID: 31924462 DOI: 10.1016/j.ymgme.2019.12.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/13/2019] [Accepted: 12/22/2019] [Indexed: 11/20/2022]
Abstract
BACKGROUND Phenylketonuria (PKU) is an inborn error of phenylalanine (Phe) metabolism. Besides dietary treatment, some patients are responsive to and treated with tetrahydrobiopterin (BH4). Our primary objective was to examine whether the 48-hour BH4 loading test misses BH4-responsive PKU patients. Secondary, we assessed if it would be beneficial to 1) use a cut-off value of 20% Phe reduction instead of commonly used 30%, and 2) extend the loading test to 7 days. METHODS 24 patients with a 20-30% decrease of blood Phe levels during their initial 48-hour BH4 loading test or at least one mutation associated with long-term BH4 responsiveness, were invited to participate. 22 of them underwent the 7-day BH4 loading test. During the BH4 loading test, BH4 was administered orally once daily for 7 days (20 mg/kg/day). Blood samples on filter paper were collected at 13 time points. Potential BH4 responders (≥20% decrease in blood Phe concentrations at ≥1 moment within the first 48 h or ≥30% at ≥1 moment during the entire test) underwent a treatment trial to assess true long-term responsiveness (≥30% decrease of Phe levels compared to baseline and/or ≥50% increase in natural protein tolerance in accordance with the Dutch guidelines before 2017). The duration of the treatment trial varied from 2 to 18 months. RESULTS Of the 22 patients who completed the 7-day BH4 loading test, 2 were excluded, 8 had negative tests and 12 were considered to be potential BH4 responders. Of these 12 potential BH4-responsive PKU patients, 5 turned out to be false positive, 6 true-responder and 1 was withdrawn. CONCLUSION Even though the 48-hour BH4 loading test has proven its efficacy in the past, a full week may be necessary to detect all responders. So, if blood Phe concentrations during the 48-hour BH4 test shows a clear tendency, but not sufficient decrease, a full week (with only measurements each 24 h) could be offered. A threshold of ≥20% decrease within 48 h is not useful for predicting true BH4 responsiveness.
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Affiliation(s)
- Annemiek M J van Wegberg
- Department of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Centre Groningen, the Netherlands
| | - Roeland A F Evers
- Department of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Centre Groningen, the Netherlands
| | - Esther van Dam
- Department of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Centre Groningen, the Netherlands
| | - Maaike C de Vries
- Department of Paediatrics, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Mirian C H Janssen
- Department of Internal Medicine, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - M Rebecca Heiner-Fokkema
- Department of Laboratory Medicine, Laboratory of Metabolic Diseases, University of Groningen, University Medical Centre Groningen, the Netherlands
| | - Francjan J van Spronsen
- Department of Metabolic Diseases, Beatrix Children's Hospital, University of Groningen, University Medical Centre Groningen, the Netherlands.
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Evers RAF, van Wegberg AMJ, Anjema K, Lubout CMA, van Dam E, van Vliet D, Blau N, van Spronsen FJ. The first European guidelines on phenylketonuria: Usefulness and implications for BH 4 responsiveness testing. J Inherit Metab Dis 2020; 43:244-250. [PMID: 31503351 DOI: 10.1002/jimd.12173] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 08/28/2019] [Accepted: 09/09/2019] [Indexed: 01/27/2023]
Abstract
OBJECTIVE This study aimed to investigate and improve the usefulness of the 48-hour BH4 loading test and to assess genotype for BH4 responsiveness prediction, using the new definition of BH4 responsiveness from the European guidelines, as well as an amended definition. METHOD Applying the definition of the European guidelines (≥100% increase in natural protein tolerance) and an amended definition (≥100% increase in natural protein tolerance or tolerating a safe natural protein intake) to a previous dataset, we first assessed the positive predictive value (PPV) of the 48-hour BH4 loading test using a cutoff value of 30%. Then, we tried to improve this PPV by using different cutoff values and separate time points. Last, using the BIOPKU database, we compared predicted BH4 responsiveness (according to genotype) and genotypic phenotype values (GPVs) in BH4 -responsive and BH4 -unresponsive patients. RESULTS The PPV of the 48-hour loading test was 50.0% using the definition of the European guidelines, and 69.4% when applying the amended definition of BH4 responsiveness. Higher cutoff values led to a higher PPV, but resulted in an increase in false-negative tests. Parameters for genotype overlapped between BH4 -responsive and BH4 -unresponsive patients, although BH4 responsiveness was not observed in patients with a GPV below 2.4. CONCLUSION The 48-hour BH4 loading test is not as useful as previously considered and cannot be improved easily, whereas genotype seems mainly helpful in excluding BH4 responsiveness. Overall, the definition of BH4 responsiveness and BH4 responsiveness testing require further attention.
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Affiliation(s)
- Roeland A F Evers
- Beatrix Children's Hospital, Division of Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Annemiek M J van Wegberg
- Beatrix Children's Hospital, Division of Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Karen Anjema
- Beatrix Children's Hospital, Division of Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Charlotte M A Lubout
- Beatrix Children's Hospital, Division of Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Esther van Dam
- Beatrix Children's Hospital, Division of Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Danique van Vliet
- Beatrix Children's Hospital, Division of Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Nenad Blau
- University Children's Hospital Zürich, Zürich, Switzerland
| | - Francjan J van Spronsen
- Beatrix Children's Hospital, Division of Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Liguori L, Monticelli M, Allocca M, Hay Mele B, Lukas J, Cubellis MV, Andreotti G. Pharmacological Chaperones: A Therapeutic Approach for Diseases Caused by Destabilizing Missense Mutations. Int J Mol Sci 2020; 21:ijms21020489. [PMID: 31940970 PMCID: PMC7014102 DOI: 10.3390/ijms21020489] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/08/2020] [Accepted: 01/09/2020] [Indexed: 02/07/2023] Open
Abstract
The term “pharmacological chaperone” was introduced 20 years ago. Since then the approach with this type of drug has been proposed for several diseases, lysosomal storage disorders representing the most popular targets. The hallmark of a pharmacological chaperone is its ability to bind a protein specifically and stabilize it. This property can be beneficial for curing diseases that are associated with protein mutants that are intrinsically active but unstable. The total activity of the affected proteins in the cell is lower than normal because they are cleared by the quality control system. Although most pharmacological chaperones are reversible competitive inhibitors or antagonists of their target proteins, the inhibitory activity is neither required nor desirable. This issue is well documented by specific examples among which those concerning Fabry disease. Direct specific binding is not the only mechanism by which small molecules can rescue mutant proteins in the cell. These drugs and the properly defined pharmacological chaperones can work together with different and possibly synergistic modes of action to revert a disease phenotype caused by an unstable protein.
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Affiliation(s)
- Ludovica Liguori
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania “Luigi Vanvitelli”, 81100 Caserta, Italy; (L.L.); (M.A.)
- Istituto di Chimica Biomolecolare–CNR, 80078 Pozzuoli, Italy;
| | - Maria Monticelli
- Dipartimento di Biologia, Università Federico II, 80126 Napoli, Italy;
| | - Mariateresa Allocca
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania “Luigi Vanvitelli”, 81100 Caserta, Italy; (L.L.); (M.A.)
- Istituto di Chimica Biomolecolare–CNR, 80078 Pozzuoli, Italy;
| | - Bruno Hay Mele
- Integrative Marine Ecology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy;
| | - Jan Lukas
- Translational Neurodegeneration Section “Albrecht-Kossel”, Department of Neurology, University Medical Center Rostock, University of Rostock, 18147 Rostock, Germany;
- Center for Transdisciplinary Neurosciences Rostock (CTNR), University Medical Center Rostock, University of Rostock, 18147 Rostock, Germany
| | - Maria Vittoria Cubellis
- Istituto di Chimica Biomolecolare–CNR, 80078 Pozzuoli, Italy;
- Dipartimento di Biologia, Università Federico II, 80126 Napoli, Italy;
- Correspondence: ; Tel.: +39-081-679118; Fax: +39-081-679233
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Moro CA, Hanna-Rose W. Animal Model Contributions to Congenital Metabolic Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1236:225-244. [PMID: 32304075 PMCID: PMC8404832 DOI: 10.1007/978-981-15-2389-2_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Genetic model systems allow researchers to probe and decipher aspects of human disease, and animal models of disease are frequently specifically engineered and have been identified serendipitously as well. Animal models are useful for probing the etiology and pathophysiology of disease and are critical for effective discovery and development of novel therapeutics for rare diseases. Here we review the impact of animal model organism research in three examples of congenital metabolic disorders to highlight distinct advantages of model system research. First, we discuss phenylketonuria research where a wide variety of research fields and models came together to make impressive progress and where a nearly ideal mouse model has been central to therapeutic advancements. Second, we review advancements in Lesch-Nyhan syndrome research to illustrate the role of models that do not perfectly recapitulate human disease as well as the need for multiple models of the same disease to fully investigate human disease aspects. Finally, we highlight research on the GM2 gangliosidoses Tay-Sachs and Sandhoff disease to illustrate the important role of both engineered traditional laboratory animal models and serendipitously identified atypical models in congenital metabolic disorder research. We close with perspectives for the future for animal model research in congenital metabolic disorders.
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Affiliation(s)
- Corinna A Moro
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Wendy Hanna-Rose
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA.
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23
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Nyuzuki H, Yamazaki T, Saito M, Ohtake A. First Japanese case of maternal phenylketonuria treated with sapropterin dihydrochloride and the normal growth and development of the child. Mol Genet Metab Rep 2019; 21:100526. [PMID: 31720228 PMCID: PMC6839020 DOI: 10.1016/j.ymgmr.2019.100526] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/19/2019] [Accepted: 09/19/2019] [Indexed: 01/21/2023] Open
Abstract
Sapropterin dihydrochloride (SD) may be a new treatment option for women with phenylketonuria (PKU) who plan to become pregnant. We report the first Japanese case of maternal PKU treated with SD. The patient was administered SD at 10-20 mg/kg/day, which increased phenylalanine tolerance during the pregnancy and lactation. No adverse events occurred, and she delivered a healthy neonate. Normal growth and development of the child confirms the efficacy and safety of SD.
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Affiliation(s)
- Hiromi Nyuzuki
- Department of Pediatrics, Niigata University, Niigata, Japan
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
- Department of Pediatrics, Saitama Medical University, Saitama, Japan
| | - Taro Yamazaki
- Department of Pediatrics, Saitama Medical University, Saitama, Japan
| | - Megumi Saito
- Department of Clinical Genomics, Saitama Medical University, Saitama, Japan
| | - Akira Ohtake
- Department of Pediatrics, Saitama Medical University, Saitama, Japan
- Department of Clinical Genomics, Saitama Medical University, Saitama, Japan
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Large Neutral Amino Acid Therapy Increases Tyrosine Levels in Adult Patients with Phenylketonuria: A Long-Term Study. Nutrients 2019; 11:nu11102541. [PMID: 31640267 PMCID: PMC6835503 DOI: 10.3390/nu11102541] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/14/2019] [Accepted: 10/16/2019] [Indexed: 12/23/2022] Open
Abstract
The standard treatment for phenylketonuria (PKU) is a lifelong low-phenylalanine (Phe) diet, supplemented with Phe-free protein substitutes; however, adult patients often show poor adherence to therapy. Alternative treatment options include the use of large neutral amino acids (LNAA). The aim of this study was to determine the Phe, tyrosine (Tyr), and Phe/Tyr ratio in a cohort of sub-optimally controlled adult patients with classical PKU treated with a new LNAA formulation. Twelve patients received a Phe-restricted diet plus a slow-release LNAA product taken three times per day, at a dose of 1 g/kg body weight (mean 0.8 ± 0.24 g/kg/day), over a 12-month period. The product is in a microgranulated formulation, which incorporates all amino acids and uses sodium alginate as a hydrophilic carrier to prolong its release. This LNAA formulation provides up to 80% of the total protein requirement, with the rest of the protein supplied by natural food. Patients had fortnightly measurements of Phe and Tyr levels over a 12-month period after the introduction of LNAA. All patients completed the 12-month treatment period. Overall, adherence to the new LNAA tablets was very good compared with a previous amino acid mixture, for which taste was a major complaint by patients. Phe levels remained unchanged (p = 0.0522), and Tyr levels increased (p = 0.0195). Consequently, the Phe/Tyr ratio decreased significantly (p < 0.05) in the majority of patients treated. In conclusion, LNAA treatment increases Tyr levels in sub-optimally controlled adult PKU patients, while offering the potential to improve their adherence to treatment.
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Leuzzi V, Chiarotti F, Nardecchia F, van Vliet D, van Spronsen FJ. Predictability and inconsistencies of cognitive outcome in patients with phenylketonuria and personalised therapy: the challenge for the future guidelines. J Med Genet 2019; 57:145-150. [DOI: 10.1136/jmedgenet-2019-106278] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/06/2019] [Accepted: 08/11/2019] [Indexed: 11/04/2022]
Abstract
Phenylketonuria (PKU) is a prototypical model of a neurodevelopmental metabolic disease that follows a cascade of pathological events affecting brain maturation and functioning. Neonatal screening and early treatment have eradicated the classical PKU phenotype in patients with early and continuously treated phenylketonuria (ECTPKU). However, effort is required to optimise the treatment of the disease to minimise the risk of lifelong neurological, cognitive and behavioural impairment, and to solve issues on the variability in clinical outcome that are rather not understood and has yet hampered a more personalised approach to its treatment. The aim of the present review is to focus on the inconsistencies in the clinical outcome of adult patients with ECTPKU unexplained by the biochemical markers adopted for the monitoring of the disease to date. The interindividual variability of clinical outcome in late as well as in early treated patients under similar biochemical control suggests the existence of disease-independent determinants influencing the individual vulnerability to the neurotoxic effect of phenylalanine. This is further supported by the low predictive power of blood phenylalanine on the clinical outcome from the second decade of life onwards. In conclusion, individual vulnerability to the metabolic alterations of PKU contributes to the prognosis of PKU, also in patients with ECTPKU. The biological factors constitutive of this vulnerability are unknown (but have not been the object of many studies so far) and should be the target of further research as prerequisite for a personalised treatment aimed at avoiding burden and costs of overtreatment and clinical consequences and risks of undertreatment in patients with PKU.
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Gundorova P, Kuznetsova IA, Agladze D, Margvelashvili L, Kldiashvili E, Kvlividze O, Kutsev SI, Polyakov AV. Molecular-Genetic Study of Phenylketonuria in Patients from Georgia. RUSS J GENET+ 2019. [DOI: 10.1134/s1022795419080064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Muntau AC, Adams DJ, Bélanger-Quintana A, Bushueva TV, Cerone R, Chien YH, Chiesa A, Coşkun T, de Las Heras J, Feillet F, Katz R, Lagler F, Piazzon F, Rohr F, van Spronsen FJ, Vargas P, Wilcox G, Bhattacharya K. International best practice for the evaluation of responsiveness to sapropterin dihydrochloride in patients with phenylketonuria. Mol Genet Metab 2019; 127:1-11. [PMID: 31103398 DOI: 10.1016/j.ymgme.2019.04.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 03/14/2019] [Accepted: 04/13/2019] [Indexed: 12/26/2022]
Abstract
Phenylketonuria (PKU) is an inherited metabolic disease caused by phenylalanine hydroxylase (PAH) deficiency. As the resulting high blood phenylalanine (Phe) concentration can have detrimental effects on brain development and function, international guidelines recommend lifelong control of blood Phe concentration with dietary and/or medical therapy. Sapropterin dihydrochloride is a synthetic preparation of tetrahydrobiopterin (6R-BH4), the naturally occurring cofactor of PAH. It acts as a pharmacological chaperone, reducing blood Phe concentration and increasing dietary Phe tolerance in BH4-responsive patients with PAH deficiency. Protocols to establish responsiveness to sapropterin dihydrochloride vary widely. Two meetings were held with an international panel of clinical experts in PKU management to develop recommendations for sapropterin dihydrochloride response testing. At the first meeting, regional differences and similarities in testing practices were discussed based on guidelines, a literature review, outcomes of a global physician survey, and case reports. Statements developed based on the discussions were sent to all participants for consensus (>70% of participants) evaluation using a 7-level rating system, and further discussed during the second meeting. The experts recommend sapropterin dihydrochloride response testing in patients with untreated blood Phe concentrations of 360-2000 μmol/L, except in those with two null mutations. For neonates, a 24-h sapropterin dihydrochloride loading test is recommended; responsiveness is defined as a decrease in blood Phe ≥30%. For older infants, children, adolescents, and adults, a test duration of ≥48 h or a 4-week trial is recommended. The main endpoint for a 48-h to 7-day trial is a decrease in blood Phe, while improved Phe tolerance is the endpoint to be assessed during a longer trial. Longer trials may not be feasible in some locations due to lack of reimbursement for hospitalization, while a 4-week trial may not be possible due to limited access to sapropterin dihydrochloride or public health regulation. A 48-h response test should be considered in pregnant patients who cannot achieve blood Phe ≤360 μmol/L with a Phe-restricted diet. Durability of response and clinical benefits of sapropterin dihydrochloride should be assessed over the long term. Harmonization of protocols is expected to improve identification of responders and comparability of test results worldwide.
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Affiliation(s)
- Ania C Muntau
- University Children's Hospital, University Medical Center Hamburg Eppendorf, Hamburg, Germany.
| | - Darius J Adams
- Atlantic Health System, Morristown Medical Center, Morristown, NJ, USA.
| | | | - Tatiana V Bushueva
- National Medical Research Center of Children's Health of the Ministry of Health of the Russian Federation, Moscow, Russia.
| | - Roberto Cerone
- G. Gaslini Institute, University of Genova, Genova, Italy.
| | | | - Ana Chiesa
- Centro de Investigaciones Endocrinologicas "Dr Cesar Bergadá" CEDIE, CONICET, Hospital de Niños Ricardo Gutierrez, Fundacion de Endocrinologia Infantil, Buenos Aires, Argentina.
| | - Turgay Coşkun
- Hacettepe University Faculty of Medicine, Ankara, Turkey.
| | - Javier de Las Heras
- Hospital Universitario de Cruces, Biocruces Health Research Institute and University of the Basque Country UPV/EHU, Vizcaya, Spain.
| | - François Feillet
- Children's University Hospital, CHU Brabois, Vandoeuvre les Nancy, France.
| | - Rachel Katz
- Ann and Robert Lurie Children's Hospital of Chicago, Chicago, IL, USA.
| | | | - Flavia Piazzon
- Associação de Pais e Amigos dos Excepcionais de São Paulo (APAE DE SÃO PAULO), São Paulo, SP, Brazil.
| | - Fran Rohr
- Boston Children's Hospital, Boston, MA, USA.
| | - Francjan J van Spronsen
- Beatrix Children's Hospital, University Medical Center of Groningen, University of Groningen, Groningen, the Netherlands.
| | - Paula Vargas
- Hospital Materno Infantil Presidente Vargas, Porto Alegre, RS, Brazil.
| | - Gisela Wilcox
- University of Manchester & Salford Royal NHS Foundation Trust, Salford, UK.
| | - Kaustuv Bhattacharya
- Genetic Metabolic Disorders Service, University of Sydney, Children's Hospital Westmead Clinical School, Sydney, NSW, Australia.
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Kölker S. Metabolism of amino acid neurotransmitters: the synaptic disorder underlying inherited metabolic diseases. J Inherit Metab Dis 2018; 41:1055-1063. [PMID: 29869166 DOI: 10.1007/s10545-018-0201-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 05/09/2018] [Accepted: 05/14/2018] [Indexed: 10/14/2022]
Abstract
Amino acids are involved in various metabolic pathways and some of them also act as neurotransmitters. Since biosynthesis of L-glutamate and γ-aminobutyric acid (GABA) requires 2-oxoglutarate while 3-phosphoglycerate is the precursor of L-glycine and D-serine, evolutionary selection of these amino acid neurotransmitters might have been driven by their capacity to provide important information about the glycolytic pathway and Krebs cycle. Synthesis and recycling of amino acid neurotransmitters as well as composition and function of their receptors are often compromised in inherited metabolic diseases. For instance, increased plasma L-phenylalanine concentrations impair cerebral biosynthesis of protein and bioamines in phenylketonuria, while elevated cerebral L-phenylalanine directly acts via ionotropic glutamate receptors. In succinic semialdehyde dehydrogenase deficiency, the neurotransmitter GABA and neuromodulatory γ-hydroxybutyric acid are elevated. Chronic hyperGABAergic state results in progressive downregulation of GABAA and GABAB receptors and impaired mitophagy. In glycine encephalopathy, the neurological phenotype is precipitated by L-glycine acting both via cortical NMDA receptors and glycine receptors in spinal cord and brain stem neurons. Serine deficiency syndromes are biochemically characterized by decreased biosynthesis of L-serine, an important neurotrophic factor, and the neurotransmitters D-serine and L-glycine. Supplementation with L-serine and L-glycine has a positive effect on seizure frequency and spasticity, while neurocognitive development can only be improved if treatment starts in utero or immediately postnatally. With novel techniques, the study of synaptic dysfunction in inherited metabolic diseases has become an emerging research field. More and better therapies are needed for these difficult-to-treat diseases.
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Affiliation(s)
- Stefan Kölker
- Division of Pediatric Neurology and Metabolic Medicine, Centre for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany.
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29
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Rocha JC, MacDonald A. Treatment options and dietary supplements for patients with phenylketonuria. Expert Opin Orphan Drugs 2018. [DOI: 10.1080/21678707.2018.1536541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Júlio César Rocha
- Centro de Genética Médica, Centro Hospitalar do Porto - CHP, Porto, Portugal
- Faculdade de Ciências da Saúde, Universidade Fernando Pessoa, Porto, Portugal
- Center for Health Technology and Services Research (CINTESIS), Porto, Portugal
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30
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Brantley KD, Douglas TD, Singh RH. One-year follow-up of B vitamin and Iron status in patients with phenylketonuria provided tetrahydrobiopterin (BH4). Orphanet J Rare Dis 2018; 13:192. [PMID: 30373601 PMCID: PMC6206913 DOI: 10.1186/s13023-018-0923-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 10/02/2018] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND People with Phenylketonuria (PKU) who respond to tetrahydrobiopterin (BH4) often decrease dependence on medical food (MF) following increased phenylalanine (phe) tolerance. Responders to BH4 may experience a reduction in certain nutrients if not compensated through intact foods or supplements. This study investigated B6, B12, folate, and iron status based on blood levels and dietary intake in patients with PKU responsive to BH4 over 1 year. METHODS Fifty-eight patients with PKU, ages 4-50 years were recruited and initiated on BH4 therapy. Patients were monitored for BH4 response, and nutritional status was recorded at regular intervals over 12 months. The analysis included 33 patients with known BH4 response status and complete nutritional data. Nutrient intake was determined by National Data System for Research (NDSR) analysis of self reported 3 day diet records and compared to Dietary Reference Intakes (DRIs). Blood biomarkers were analyzed by Quest Diagnostics and compared to laboratory reference ranges. Patient laboratory values were compared to controls from the National Health and Examination Survey (NHANES). Differences in nutrient intakes across time points were examined, stratified by age, using nonparametric methods. Statistical analyses were completed with SAS 9.4, with significance set at α = 0.05. RESULTS Medical food intake declined among pediatric (p < 0.01) and adult (p = 0.06) BH4 responders over 1 year. Among those < 18 years of age, mean percent of calories obtained from MF declined from 21.3 to 4.7%. In adults, percent calories from MF dropped from 19.5 to 4.0%. Though maintaining laboratory and dietary values within reference ranges, responders < 18 years experienced a significant decline in serum B12 (p = 0.01), dietary folate (p = 0.006), and dietary iron (p = 0.004) over the study. CONCLUSION Although mean dietary and laboratory values for B12, B6, folate, and iron in BH4 responders and non-responders were adequate at baseline and 12-month follow-up, responders experienced a significant decline in serum B12 over 1 year, which may be explained by decreased intake of fortified MF. Both response groups had lower serum B12 than NHANES controls at baseline and 12 months. Results indicate a need to monitor B12 concentrations and consider micronutrient supplementation, with special attention to pediatric patients with PKU.
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Affiliation(s)
| | - Teresa D Douglas
- Department of Human Genetics, Metabolic Nutrition Program, Emory University School of Medicine, Atlanta, GA USA
| | - Rani H Singh
- Department of Human Genetics, Metabolic Nutrition Program, Emory University School of Medicine, Atlanta, GA USA
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31
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Muntau AC, du Moulin M, Feillet F. Diagnostic and therapeutic recommendations for the treatment of hyperphenylalaninemia in patients 0-4 years of age. Orphanet J Rare Dis 2018; 13:173. [PMID: 30268140 PMCID: PMC6162894 DOI: 10.1186/s13023-018-0911-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 09/12/2018] [Indexed: 12/17/2023] Open
Abstract
BACKGROUND Treatment of phenylketonuria (PKU) with sapropterin dihydrochloride in responsive patients from an early age can have many advantages for the patient over dietary restriction alone. Accordingly, approval of sapropterin in the European Union was extended in 2015 to include patients aged 0-4 years, bringing the treatment age range in line with that in the USA and providing an additional treatment option for those patients with PKU who are responsive or partially responsive to treatment with sapropterin. Subsequently, European guidelines have been published on the diagnosis and management of patients with PKU. However, testing for PKU can be demanding and requires particular expertise. We have compiled experience-based, real-world guidance in an algorithmic format to complement the published guidelines, with the overall aim to achieve optimized and individualized care for patients with PKU. RESULTS Our guidance covers aspects such as how to perform, monitor and interpret appropriate biochemical measures to achieve effective patient management and desired outcomes, how to perform a tetrahydrobiopterin (BH4) loading test to assess responsiveness in newborns, and how to initiate sapropterin treatment in patients from birth. We also provide our expert opinion on starting pharmacotherapy in patients who were previously managed by diet alone. CONCLUSIONS Real-world-based guidance is particularly important in managing therapeutic strategies in newborns with PKU to achieve optimal long-term outcomes and will serve as a complement to the other published guidelines.
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Affiliation(s)
- Ania C. Muntau
- University Children’s Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marcel du Moulin
- University Children’s Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Francois Feillet
- Department of Pediatrics, Hôpital d’Enfants Brabois, CHU Nancy, Vandoeuvre les Nancy, France
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32
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Garbade SF, Shen N, Himmelreich N, Haas D, Trefz FK, Hoffmann GF, Burgard P, Blau N. Allelic phenotype values: a model for genotype-based phenotype prediction in phenylketonuria. Genet Med 2018; 21:580-590. [DOI: 10.1038/s41436-018-0081-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/31/2018] [Indexed: 02/08/2023] Open
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Rabender CS, Bruno N, Alam A, Sundaresan G, Zweit J, Mikkelsen RB. Sepiapterin Enhances Tumor Radio- and Chemosensitivities by Promoting Vascular Normalization. J Pharmacol Exp Ther 2018; 365:536-543. [PMID: 29581154 PMCID: PMC11046730 DOI: 10.1124/jpet.117.245258] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/26/2018] [Indexed: 12/22/2022] Open
Abstract
Previously, we demonstrated that nitric oxide (NO) synthase (NOS) is uncoupled in a wide range of solid tumors and that restoring NOS coupling with the tetrahydrobiopterin precursor sepiapterin (SP) inhibits tumor progression. Endothelial dysfunction characterizes the poorly functional vasculature of solid tumors, and since NO is critical for regulation of endothelial function we asked whether SP, by recoupling NOS, improves tumor vasculature structure and function-enhancing chemotherapeutic delivery and response to radiotherapy. MMTV-neu mice with spontaneous breast tumors were treated with SP by oral gavage and evaluated by multispectral optoacoustic tomographic analysis of tumor HbO2 and by tissue staining for markers of hypoxia, blood perfusion, and markers of endothelial and smooth muscle proteins. Recoupling tumor NOS activity results in vascular normalization observed as reduced tumor hypoxia, improved tumor percentage of HbO2 and perfusion, as well as increased pericyte coverage of tumor blood vessels. The normalized vasculature and improved tumor oxygenation led to a greater than 2-fold increase in radiation-induced apoptosis compared with radiation or SP alone. High-performance liquid chromatography analysis of tumor doxorubicin levels showed a greater than 50% increase in doxorubicin uptake and a synergistic effect on tumor cell apoptosis. This study highlights for the first time the importance of NOS uncoupling and endothelial dysfunction in the development of tumor vasculature and presents a new approach for improving the tumoricidal efficacies of chemotherapy and radiotherapy.
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Affiliation(s)
- Christopher S Rabender
- Department of Radiation Oncology (C.S.R., N.B., A.A., R.B.M.) and Center for Molecular Imaging (G.S., J.Z.), Virginia Commonwealth University, Richmond, Virginia
| | - Ninu Bruno
- Department of Radiation Oncology (C.S.R., N.B., A.A., R.B.M.) and Center for Molecular Imaging (G.S., J.Z.), Virginia Commonwealth University, Richmond, Virginia
| | - Asim Alam
- Department of Radiation Oncology (C.S.R., N.B., A.A., R.B.M.) and Center for Molecular Imaging (G.S., J.Z.), Virginia Commonwealth University, Richmond, Virginia
| | - Gobalakrishnan Sundaresan
- Department of Radiation Oncology (C.S.R., N.B., A.A., R.B.M.) and Center for Molecular Imaging (G.S., J.Z.), Virginia Commonwealth University, Richmond, Virginia
| | - Jamal Zweit
- Department of Radiation Oncology (C.S.R., N.B., A.A., R.B.M.) and Center for Molecular Imaging (G.S., J.Z.), Virginia Commonwealth University, Richmond, Virginia
| | - Ross B Mikkelsen
- Department of Radiation Oncology (C.S.R., N.B., A.A., R.B.M.) and Center for Molecular Imaging (G.S., J.Z.), Virginia Commonwealth University, Richmond, Virginia
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Eichinger A, Danecka MK, Möglich T, Borsch J, Woidy M, Büttner L, Muntau AC, Gersting SW. Secondary BH4 deficiency links protein homeostasis to regulation of phenylalanine metabolism. Hum Mol Genet 2018; 27:1732-1742. [PMID: 29514280 DOI: 10.1093/hmg/ddy079] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 02/28/2018] [Indexed: 01/01/2023] Open
Abstract
Metabolic control of phenylalanine concentrations in body fluids is essential for cognitive development and executive function. The hepatic phenylalanine hydroxylating system is regulated by the ratio of l-phenylalanine, which is substrate of phenylalanine hydroxylase (PAH), to the PAH cofactor tetrahydrobiopterin (BH4). Physiologically, phenylalanine availability is governed by nutrient intake, whereas liver BH4 is kept at constant level. In phenylketonuria, PAH deficiency leads to elevated blood phenylalanine and is often caused by PAH protein misfolding with loss of function. Here, we report secondary hepatic BH4 deficiency in Pah-deficient mice. Alterations in de novo synthesis and turnover of BH4 were ruled out as molecular causes. We demonstrate that kinetically instable and aggregation-prone variant Pah proteins trap BH4, shifting the pool of free BH4 towards bound BH4. Interference of PAH protein misfolding with metabolite-based control of l-phenylalanine turnover suggests a mechanistic link between perturbation of protein homeostasis and disturbed regulation of metabolic pathways.
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Affiliation(s)
- Anna Eichinger
- Molecular Pediatrics, Dr von Hauner Children's Hospital, Ludwig-Maximilians-Universität, Munich, Germany
| | | | - Tamara Möglich
- Molecular Pediatrics, Dr von Hauner Children's Hospital, Ludwig-Maximilians-Universität, Munich, Germany
| | - Julia Borsch
- Molecular Pediatrics, Dr von Hauner Children's Hospital, Ludwig-Maximilians-Universität, Munich, Germany
| | - Mathias Woidy
- University Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Lars Büttner
- Molecular Pediatrics, Dr von Hauner Children's Hospital, Ludwig-Maximilians-Universität, Munich, Germany
| | - Ania C Muntau
- University Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Yuan TF, Huang HQ, Gao L, Wang ST, Li Y. A novel and reliable method for tetrahydrobiopterin quantification: Benzoyl chloride derivatization coupled with liquid chromatography-tandem mass spectrometry analysis. Free Radic Biol Med 2018; 118:119-125. [PMID: 29501564 DOI: 10.1016/j.freeradbiomed.2018.02.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 02/02/2018] [Accepted: 02/26/2018] [Indexed: 01/15/2023]
Abstract
Tetrahydrobiopterin (BH4) is a crucial cofactor for nitric oxide synthase, acylglycerol mono-oxygenase and aromatic amino acids hydroxylases. Its significant function for redox pathways in vivo attracted much attention for long. However, because of the oxidizable and substoichiometric nature, analysis of BH4 has never been truly achieved with adequate sensitivity and applicability. In the present work, we pioneeringly stabilized BH4 by derivatizing the active secondary amine on five-position with benzoyl chloride (BC). Benefiting from the favorable chemical stability and excellent mass spectrometric sensitivity of the product (BH4-BC), ultra-sensitive and reliable quantification of endogenous BH4 in plasma was achieved using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. In such methodology, BH4-BC-d5 was introduced as stable isotopic internal standard. And the limit of quantification (LOQ) could reach 0.02 ng mL-1. In the end, after investigation of plasma BH4 in healthy volunteers (n = 38), we found that the levels of BH4 were significantly and negatively correlated to age. Comparing with all the other existed strategies, the present method was obviously superior in sensitivity, specificity and practical applicability. It could be expected that this work could largely promote the future studies in BH4-related fields.
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Affiliation(s)
- Teng-Fei Yuan
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Han-Qi Huang
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Ling Gao
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Shao-Ting Wang
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China.
| | - Yan Li
- Department of Clinical Laboratory, Renmin Hospital of Wuhan University, Wuhan 430060, China.
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Arbesman J, Ravichandran S, Funchain P, Thompson CL. Melanoma cases demonstrate increased carrier frequency of phenylketonuria/hyperphenylalanemia mutations. Pigment Cell Melanoma Res 2018; 31:529-533. [PMID: 29473999 DOI: 10.1111/pcmr.12695] [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: 09/20/2017] [Accepted: 02/09/2018] [Indexed: 11/30/2022]
Abstract
Identifying novel melanoma genetic risk factors informs screening and prevention efforts. Mutations in the phenylalanine hydroxylase gene (the causative gene in phenylketonuria) lead to reduced pigmentation in untreated phenylketonuria patients, and reduced pigmentation is associated with greater melanoma risk. Therefore, we sought to characterize the relationship between phenylketonuria carrier status and melanoma risk. Using National Newborn Screening Reports, we determined the United States phenylketonuria/hyperphenylalanemia carrier frequency in Caucasians to be 1.76%. We examined three publically available melanoma datasets for germline mutations in the phenylalanine hydroxylase gene associated with classic phenylketonuria and/or hyperphenylalanemia. Mutations were identified in 29/814 melanoma patients, with a carrier frequency of 3.56%. There was a twofold enrichment (p-value = 3.4 × 10-5 ) compared to the Caucasian frequency of hyperphenylalanemia/phenylketonuria carriers. These data demonstrate a novel association between phenylalanine hydroxylase carrier status and melanoma risk. Further, functional investigation is warranted to determine the link between phenylalanine hydroxylase mutations and melanomagenesis.
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Affiliation(s)
- Joshua Arbesman
- Department of Dermatology, Case Western Reserve University, Cleveland, OH, USA
| | | | - Pauline Funchain
- Department of Hematology/Oncology, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Cheryl L Thompson
- Department of Nutrition, Case Western Reserve University, Cleveland, OH, USA
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Viall S, Ayyub O, Rasberry M, Lyons K, Ah Mew N. "Mild" hyperphenylalaninemia? A case series of seven treated patients following newborn screening. Mol Genet Metab 2017; 122:153-155. [PMID: 29102225 DOI: 10.1016/j.ymgme.2017.10.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/18/2017] [Accepted: 10/19/2017] [Indexed: 11/23/2022]
Abstract
Hyperphenylalaninemia (HPA) is a disorder diagnosed only incidentally by newborn screening, a by-product of screening for classic phenylketonuria (PKU) which, if untreated, causes irreversible neurologic sequelae. In contrast, HPA is thought to have a benign phenotype because phenylalanine (Phe) levels are insufficiently elevated to cause neurological damage, obviating the need for rigorous dietary protein restriction. Phenylalanine below 360μmol/L is generally considered safe, thus this threshold is both the upper therapeutic range for treated PKU and the highest Phe expected to be possible for most individuals with HPA. However, the published literature and even expert consensus provides limited guidance on long-term follow-up of Phe after this diagnosis. In particular, how frequently and vigilantly to monitor levels to evaluate for subsequent elevations above the 'safe' range. Upon retrospective review we identified 22 patients with HPA, ascertained via newborn screen and currently aged two to thirty-six years. All patients had an initial untreated Phe between 90μmol/L (our upper limit of normal) and 360μmol/L. Of these patients, seven subsequently demonstrated either fluctuating or sustained increases in Phe above 360μmol/L. Five have been treated successfully with sapropterin therapy without dietary intervention and two have been treated with mild to moderate protein restriction. Our experience demonstrates successful treatment of these children without the traditional highly restrictive PKU diet. However, a better understanding of this disorder is necessary to more safely and appropriately identify, monitor and manage children with HPA. SYNOPSIS One clinics' experience with diagnostic differences in a population of Hyperphenylalaninemia patients that required treatment.
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Affiliation(s)
- Sarah Viall
- Division of Genetics and Metabolism, Childrens' National Health System, Washington, DC, United States.
| | - Omar Ayyub
- Division of Genetics and Metabolism, Childrens' National Health System, Washington, DC, United States
| | - Matthew Rasberry
- Biochemical Genetics Program, Waisman Center, University of Wisconsin, Madison, United States
| | - Kelly Lyons
- Division of Genetics and Metabolism, Childrens' National Health System, Washington, DC, United States
| | - Nicholas Ah Mew
- Division of Genetics and Metabolism, Childrens' National Health System, Washington, DC, United States
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38
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van Vliet D, van der Goot E, Bruinenberg VM, van Faassen M, de Blaauw P, Kema IP, Heiner-Fokkema MR, van der Zee EA, van Spronsen FJ. Large neutral amino acid supplementation as an alternative to the phenylalanine-restricted diet in adults with phenylketonuria: evidence from adult Pah-enu2 mice. J Nutr Biochem 2017; 53:20-27. [PMID: 29175141 DOI: 10.1016/j.jnutbio.2017.09.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 09/04/2017] [Accepted: 09/28/2017] [Indexed: 11/26/2022]
Abstract
Phenylketonuria treatment mainly consists of a phenylalanine-restricted diet but still results in suboptimal neuropsychological outcome, which is at least partly based on cerebral monoamine deficiencies, while, after childhood, treatment compliance decreases. Supplementation of large neutral amino acids (LNAAs) was previously demonstrated in young phenylketonuria mice to target all three biochemical disturbances underlying brain dysfunction in phenylketonuria. However, both its potential in adult phenylketonuria and the comparison with the phenylalanine-restricted diet remain to be established. To this purpose, several LNAA supplements were compared with a severe phenylalanine-restricted diet with respect to brain monoamine and amino acid concentrations in adult C57Bl/6 Pah-enu2 mice. Adult phenylketonuria mice received a phenylalanine-restricted diet, unrestricted diet supplemented with several combinations of LNAAs or AIN-93M control diet for 6 weeks. In addition, adult wild-type mice on AIN-93M diet served as controls. The severe phenylalanine-restricted diet in adult phenylketonuria mice significantly reduced plasma and brain phenylalanine and restored brain monoamine concentrations, while brain concentrations of most nonphenylalanine LNAAs remained subnormal. Supplementation of eight LNAAs was similarly effective as the severe phenylalanine-restricted diet to restore brain monoamines, while brain and plasma phenylalanine concentrations remained markedly elevated. These results provide biochemical support for the effectiveness of the severe phenylalanine-restricted diet and showed the possibilities of LNAA supplementation being equally effective to restore brain monoamines in adult phenylketonuria mice. Therefore, LNAA supplementation is a promising alternative treatment to phenylalanine restriction in adult phenylketonuria patients to further optimize neuropsychological functioning.
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Affiliation(s)
- Danique van Vliet
- University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Groningen, the Netherlands
| | - Els van der Goot
- University of Groningen, Groningen Institute for Evolutionary Life Sciences (GELIFES), Department of Molecular Neurobiology, Groningen, the Netherlands
| | - Vibeke M Bruinenberg
- University of Groningen, Groningen Institute for Evolutionary Life Sciences (GELIFES), Department of Molecular Neurobiology, Groningen, the Netherlands
| | - Martijn van Faassen
- University of Groningen, University Medical Center Groningen, Department of Laboratory Medicine, Groningen, the Netherlands
| | - Pim de Blaauw
- University of Groningen, University Medical Center Groningen, Department of Laboratory Medicine, Groningen, the Netherlands
| | - Ido P Kema
- University of Groningen, University Medical Center Groningen, Department of Laboratory Medicine, Groningen, the Netherlands
| | - M Rebecca Heiner-Fokkema
- University of Groningen, University Medical Center Groningen, Department of Laboratory Medicine, Groningen, the Netherlands
| | - Eddy A van der Zee
- University of Groningen, Groningen Institute for Evolutionary Life Sciences (GELIFES), Department of Molecular Neurobiology, Groningen, the Netherlands
| | - Francjan J van Spronsen
- University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Groningen, the Netherlands.
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van Wegberg AMJ, MacDonald A, Ahring K, Bélanger-Quintana A, Blau N, Bosch AM, Burlina A, Campistol J, Feillet F, Giżewska M, Huijbregts SC, Kearney S, Leuzzi V, Maillot F, Muntau AC, van Rijn M, Trefz F, Walter JH, van Spronsen FJ. The complete European guidelines on phenylketonuria: diagnosis and treatment. Orphanet J Rare Dis 2017; 12:162. [PMID: 29025426 PMCID: PMC5639803 DOI: 10.1186/s13023-017-0685-2] [Citation(s) in RCA: 407] [Impact Index Per Article: 58.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 07/11/2017] [Indexed: 12/22/2022] Open
Abstract
Phenylketonuria (PKU) is an autosomal recessive inborn error of phenylalanine metabolism caused by deficiency in the enzyme phenylalanine hydroxylase that converts phenylalanine into tyrosine. If left untreated, PKU results in increased phenylalanine concentrations in blood and brain, which cause severe intellectual disability, epilepsy and behavioural problems. PKU management differs widely across Europe and therefore these guidelines have been developed aiming to optimize and standardize PKU care. Professionals from 10 different European countries developed the guidelines according to the AGREE (Appraisal of Guidelines for Research and Evaluation) method. Literature search, critical appraisal and evidence grading were conducted according to the SIGN (Scottish Intercollegiate Guidelines Network) method. The Delphi-method was used when there was no or little evidence available. External consultants reviewed the guidelines. Using these methods 70 statements were formulated based on the highest quality evidence available. The level of evidence of most recommendations is C or D. Although study designs and patient numbers are sub-optimal, many statements are convincing, important and relevant. In addition, knowledge gaps are identified which require further research in order to direct better care for the future.
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Affiliation(s)
- A. M. J. van Wegberg
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, PO BOX 30.001, 9700 RB Groningen, The Netherlands
| | - A. MacDonald
- Dietetic Department, Birmingham Children’s Hospital, Birmingham, UK
| | - K. Ahring
- Department of PKU, Kennedy Centre, Glostrup, Denmark
| | - A. Bélanger-Quintana
- Metabolic Diseases Unit, Department of Paediatrics, Hospital Ramon y Cajal Madrid, Madrid, Spain
| | - N. Blau
- University Children’s Hospital, Dietmar-Hoppe Metabolic Centre, Heidelberg, Germany
- University Children’s Hospital Zürich, Zürich, Switzerland
| | - A. M. Bosch
- Department of Paediatrics, Division of Metabolic Disorders, Academic Medical Centre, University Hospital of Amsterdam, Amsterdam, The Netherlands
| | - A. Burlina
- Division of Inherited Metabolic Diseases, Department of Paediatrics, University Hospital of Padova, Padova, Italy
| | - J. Campistol
- Neuropaediatrics Department, Hospital Sant Joan de Déu, Universitat de Barcelona, Barcelona, Spain
| | - F. Feillet
- Department of Paediatrics, Hôpital d’Enfants Brabois, CHU Nancy, Vandoeuvre les Nancy, France
| | - M. Giżewska
- Department of Paediatrics, Endocrinology, Diabetology, Metabolic Diseases and Cardiology of the Developmental Age, Pomeranian Medical University, Szczecin, Poland
| | - S. C. Huijbregts
- Department of Clinical Child and Adolescent Studies-Neurodevelopmental Disorders, Faculty of Social Sciences, Leiden University, Leiden, The Netherlands
| | - S. Kearney
- Clinical Psychology Department, Birmingham Children’s Hospital, Birmingham, UK
| | - V. Leuzzi
- Department of Paediatrics, Child Neurology and Psychiatry, Sapienza University of Rome, Via dei Sabelli 108, 00185 Rome, Italy
| | - F. Maillot
- CHRU de Tours, Université François Rabelais, INSERM U1069, Tours, France
| | - A. C. Muntau
- University Children’s Hospital, University Medical Centre Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - M. van Rijn
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, PO BOX 30.001, 9700 RB Groningen, The Netherlands
| | - F. Trefz
- Department of Paediatrics, University of Heidelberg, Heidelberg, Germany
| | - J. H. Walter
- Medicine, Manchester Academic Health Sciences Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK
| | - F. J. van Spronsen
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, PO BOX 30.001, 9700 RB Groningen, The Netherlands
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40
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Porta F, Spada M, Ponzone A. Early Screening for Tetrahydrobiopterin Responsiveness in Phenylketonuria. Pediatrics 2017; 140:e20161591. [PMID: 28679641 DOI: 10.1542/peds.2016-1591] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/19/2016] [Indexed: 11/24/2022] Open
Abstract
Since 2007, synthetic tetrahydrobiopterin (BH4) has been approved as a therapeutic option in BH4-responsive phenylketonuria (PKU) and since 2015 extended to infants younger than 4 years in Europe. The current definition of BH4 responsiveness relies on the observation of a 20% to 30% blood phenylalanine (Phe) decrease after BH4 administration, under nonstandardized conditions. By this definition, however, patients with the same genotype or even the same patients were alternatively reported as responsive or nonresponsive to the cofactor. These inconsistencies are troubling, as frustrating patient expectations and impairing cost-effectiveness of BH4-therapy. Here we tried a quantitative procedure through the comparison of the outcome of a simple Phe and a combined Phe plus BH4 loading in a series of infants with PKU, most of them harboring genotypes already reported as BH4 responsive. Under these ideal conditions, blood Phe clearance did not significantly differ after the 2 types of loading, and a 20% to 30% decrease of blood Phe occurred irrespective of BH4 administration in milder forms of PKU. Such early screening for BH4 responsiveness, based on a quantitative assay, is essential for warranting an evidence-based and cost-effective therapy in those patients with PKU eventually but definitely diagnosed as responsive to the cofactor.
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Affiliation(s)
- Francesco Porta
- Department of Pediatrics, University of Torino, Torino, Italy
| | - Marco Spada
- Department of Pediatrics, University of Torino, Torino, Italy
| | - Alberto Ponzone
- Department of Pediatrics, University of Torino, Torino, Italy
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Jaffe EK. New protein structures provide an updated understanding of phenylketonuria. Mol Genet Metab 2017; 121:289-296. [PMID: 28645531 PMCID: PMC5549558 DOI: 10.1016/j.ymgme.2017.06.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 06/08/2017] [Indexed: 11/16/2022]
Abstract
Phenylketonuria (PKU) and less severe hyperphenylalaninemia (HPA) constitute the most common inborn error of amino acid metabolism, and is most often caused by defects in phenylalanine hydroxylase (PAH) function resulting in accumulation of Phe to neurotoxic levels. Despite the success of dietary intervention in preventing permanent neurological damage, individuals living with PKU clamor for additional non-dietary therapies. The bulk of disease-associated mutations are PAH missense variants, which occur throughout the entire 452 amino acid human PAH protein. While some disease-associated mutations affect protein structure (e.g. truncations) and others encode catalytically dead variants, most have been viewed as defective in protein folding/stability. Here we refine this view to address how PKU-associated missense variants can perturb the equilibrium among alternate native PAH structures (resting-state PAH and activated PAH), thus shifting the tipping point of this equilibrium to a neurotoxic Phe concentration. This refined view of PKU introduces opportunities for the design or discovery of therapeutic pharmacological chaperones that can help restore the tipping point to healthy Phe levels and how such a therapeutic might work with or without the inhibitory pharmacological chaperone BH4. Dysregulation of an equilibrium of architecturally distinct native PAH structures departs from the concept of "misfolding", provides an updated understanding of PKU, and presents an enhanced foundation for understanding genotype/phenotype relationships.
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Affiliation(s)
- Eileen K Jaffe
- Fox Chase Cancer Center - Temple University Health System, 333 Cottman Ave, Philadelphia, PA 19111, USA.
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42
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Zhu T, Ye J, Han L, Qiu W, Zhang H, Liang L, Gu X. The Predictive Value of Genetic Analyses in the Diagnosis of Tetrahydrobiopterin (BH4)-Responsiveness in Chinese Phenylalanine Hydroxylase Deficiency Patients. Sci Rep 2017; 7:6762. [PMID: 28754886 PMCID: PMC5533732 DOI: 10.1038/s41598-017-06462-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 06/13/2017] [Indexed: 11/23/2022] Open
Abstract
Molecular characterization of PAH deficiency has been proven essential in establishing treatment options. We examine the diagnostic accuracy of two genetic assays to predict BH4 responsiveness: to determine whether the AV sum test or mutation-status assessment test can obviate the need for BH4 loading in Chinese patients. The overall predicted response in 346 patients was 31.65% by the AV sum test and 25.43% by the other assay; both percentages were lower than 51.06% derived from loading results in 94 patients. Responders were compound heterozygotes with definite BH4 responsive mutations, while non-responders had null/null ones; some consistently with specific mutations and genotypes. The sensitivity and specificity of the assays were 81.1% and 92.5% for the AV sum, and 82.9%, 97.3% for the other. An AV sum cutoff >2 has a positive predictive value (PPV) of 90.9%, while the presence of at least one BH4 responsive mutation has a PPV of 97.1%. The two approaches showed good concordance. Our data confirmed that the mutation-status assessment has a higher diagnostic accuracy in predicting response for Chinese patients than the AV sum test. BH4-responsiveness may be predicted or excluded from patients' molecular characteristics to some extent, thus some patients may avoid the initial loading.
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Affiliation(s)
- Tianwen Zhu
- Department of Neonatal Medicine, Xin-Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jun Ye
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lianshu Han
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenjuan Qiu
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Huiwen Zhang
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lili Liang
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xuefan Gu
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Feldmann R, Wolfgart E, Weglage J, Rutsch F. Sapropterin treatment does not enhance the health-related quality of life of patients with phenylketonuria and their parents. Acta Paediatr 2017; 106:953-959. [PMID: 28235150 DOI: 10.1111/apa.13799] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 09/23/2016] [Accepted: 02/21/2017] [Indexed: 01/17/2023]
Abstract
AIM Sapropterin causes reductions in blood phenylalanine concentrations in sensitive patients with phenylketonuria (PKU). We examined whether the subsequent relaxation of dietary restrictions influenced the quality of life (QoL) of patients and parents. METHODS The study cohort comprised 112 patients with PKU followed at the metabolic centre at Münster University Children's Hospital, Germany, from 2012 to 2015. A sapropterin response was defined as a ≥30% reduction in blood phenylalanine levels. The QoL of 38 children and adolescents from the study cohort, with a mean age of 12.4 (range 6.6-18.7) years, was assessed in an outpatient setting and 49 parents of children with PKU also commented on their child's QoL and their own. The participants' QoL was assessed before the start of therapy, and again after six months, using self-report questionnaires. RESULTS After six months of continuous therapy or diet, QoL was largely unchanged in the patients, according to their self-reports and the parental reports. QoL also remained unchanged in the parents. CONCLUSION Sapropterin did not seem to improve QoL in PKU patients and their parents. Patients with PKU had already reached high levels of QoL following classic diets, and these levels were not easily improved by sapropterin.
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Affiliation(s)
- Reinhold Feldmann
- Department of General Pediatrics, Münster University Children's Hospital, Münster, Germany
| | - Eva Wolfgart
- Department of General Pediatrics, Münster University Children's Hospital, Münster, Germany
| | - Josef Weglage
- Department of General Pediatrics, Münster University Children's Hospital, Münster, Germany
| | - Frank Rutsch
- Department of General Pediatrics, Münster University Children's Hospital, Münster, Germany
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Trunzo R, Santacroce R, Shen N, Jung-Klawitter S, Leccese A, De Girolamo G, Margaglione M, Blau N. In vitro residual activity of phenylalanine hydroxylase variants and correlation with metabolic phenotypes in PKU. Gene 2016; 594:138-143. [PMID: 27620137 DOI: 10.1016/j.gene.2016.09.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/29/2016] [Accepted: 09/08/2016] [Indexed: 10/21/2022]
Abstract
Hyperphenylalaninemias (HPAs) are genetic diseases predominantly caused by a wide range of variants in the phenylalanine hydroxylase (PAH) gene. In vitro expression analysis of PAH variants offers the opportunity to elucidate the molecular mechanisms involved in HPAs and to clarify whether a disease-associated variant is genuinely pathogenic, while investigating the severity of a metabolic phenotype, and determining how a variant exerts its deleterious effects on the PAH enzyme. To study the effects of gene variants on PAH activity, we investigated eight variants: c.611A>G (p.Y204C), c.635T>C (p.L212P), c.746T>C (p.L249P), c.745C>T (p.L249F), c.809G>A (p.R270K), c.782G>C (p.R261P), c.587C>A (p.S196Y) and c.1139C>T (p.T380M), associated with different phenotypic groups. Transient expression of mutant full-length cDNAs in COS-7 cells yielded PAH proteins with PAH activity levels between 7% and 51% compared to the wild-type enzyme. With one exception (p.Y204C, which had no significant impact on PAH function), lower PAH activity was associated with a more severe phenotype (e.g. p.L249P with 7% PAH activity, 100% of classic PKU and no BH4 responsiveness), while higher activity correlated with milder phenotypes (e.g. p.T380M with 28% PAH activity, 97% of mild HPA and 83% of BH4 responsiveness). The results of the in vitro residual PAH activity have major implications, both for our understanding of genotype-phenotype correlations, and thereby existing inconsistencies, but also for the elucidation of the molecular basis of tetrahydrobiopterin (BH4) responsiveness.
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Affiliation(s)
- Roberta Trunzo
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy.
| | - Rosa Santacroce
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Nan Shen
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Sabine Jung-Klawitter
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Angelica Leccese
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Giuseppe De Girolamo
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Maurizio Margaglione
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Nenad Blau
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
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Abstract
More than 950 phenylalanine hydroxylase (PAH) gene variants have been identified in people with phenylketonuria (PKU). These vary in their consequences for the residual level of PAH activity, from having little or no effect to abolishing PAH activity completely. Advances in genotyping technology and the availability of locus-specific and genotype databases have greatly expanded our understanding of the correlations between individual gene variant, residual PAH activity, tetrahydrobiopterin (BH4 ) responsiveness, and the clinical PKU phenotype. Most patients (∼76%) have compound heterozygous PAH gene variants and one mutated allele may markedly influence the activity of the second mutated allele, which in turn may influence either positively or negatively the activity of the biologically active heterotetrameric form of the PAH. While it is possible to predict the level of BH4 responsiveness (∼71%) and PKU severity (∼78%) from the nature of the underlying gene variants, these relationships remain complex and incompletely understood. A greater understanding of these relationships may increase the potential for individualized management of PKU in future. Inherited deficiencies in BH4 metabolism account for about 1%-2% of all hyperphenylalaninemias and are clinically more severe than PKU. Almost 90% of all patients are deficient in 6-pyruvoyl-tetrahydropterin synthase and dihydropteridine reductase.
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Affiliation(s)
- Nenad Blau
- Dietmar-Hopp-Metabolic Center, University Children's Hospital, Heidelberg, Germany
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Tao J, Li N, Jia H, Liu Z, Li X, Song J, Deng Y, Jin X, Zhu J. Correlation between genotype and the tetrahydrobiopterin-responsive phenotype in Chinese patients with phenylketonuria. Pediatr Res 2015; 78:691-9. [PMID: 26322415 PMCID: PMC4700046 DOI: 10.1038/pr.2015.167] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 06/17/2015] [Indexed: 01/30/2023]
Abstract
BACKGROUND A growing body of research has suggested that tetrahydrobiopterin (BH4) responsive phenotype can be predicted by the phenylalanine hydroxylase (PAH) genotype in patients with phenylketonuria (PKU), but data concerning the association between genotype and BH4 responsiveness are scarce in China. METHODS A total of 165 PKU patients from China who had undergone a 24-h loading test with BH4 administration were recruited. Genotyping was performed by the next-generation sequencing (NGS) technique. Using the predicted residual PAH activity, we analyzed the association between genotype and BH4-responsiveness. RESULTS Among the 165 patients, 40 patients (24.24%) responded to BH4. A total of 74 distinct mutations were observed, including 13 novel mutations. The mutation p.R241C was most frequently associated with response. Two known mutations (p.A322T and p.Q419R) and two novel mutations (p.L98V and IVS3-2A>T) were first reported as responsive to BH4. Residual PAH activity of at least 12.5% was needed for responsive genotypes. CONCLUSION Genotype-based predictions of BH4-responsiveness are only for selecting potential responders. Accordingly, it is necessary to test potential responders with a long-term BH4 challenge.
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Affiliation(s)
- Jing Tao
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- West China School of Public Health, Sichuan University, Sichuan, China
| | - Nana Li
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | - Haitao Jia
- BGI-Shenzhen, Shenzhen, Guangdong, China
| | - Zhen Liu
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | - Xiaohong Li
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | | | - Ying Deng
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | - Xi Jin
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | - Jun Zhu
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
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Trunzo R, Santacroce R, D'Andrea G, Longo V, De Girolamo G, Dimatteo C, Leccese A, Bafunno V, Lillo V, Papadia F, Margaglione M. Phenylalanine hydroxylase deficiency in south Italy: Genotype-phenotype correlations, identification of a novel mutant PAH allele and prediction of BH4 responsiveness. Clin Chim Acta 2015; 450:51-5. [PMID: 26210745 DOI: 10.1016/j.cca.2015.07.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 07/13/2015] [Accepted: 07/14/2015] [Indexed: 10/23/2022]
Abstract
We investigated the mutation spectrum of the phenylalanine hydroxylase gene (PAH) in a cohort of patients from 33 Italian PKU families. Mutational screening of the known coding region, including conventional intron splice sites, was performed by direct sequencing of the patients' genomic DNA. Thirty-three different disease causing mutations were identified in our patient group, including 19 missense, 6 splicing, 3 nonsense, 5 deletions, with a detection rate of 100%. The most prevalent mutation was the IVS10-11G>A, accounting for 12.1% of PKU alleles studied. Other frequent mutations were: p.R261Q (9.1%), p.P281L (7.6%), and p.R408W (6.1%). We also identified one novel missense mutation, p.H290Q. A spectrum of 31 different genotypes was observed and a genotype based predictions of BH4-responsiveness were assessed. Among all genotypes, 13 were predicted to be BH4-responsive represented by thirteen PKU families. In addition, genotype-phenotype correlations were performed. This study reveals the importance of a full genotyping of PKU patients and the prediction of BH4-responsiveness, not only because of the definitive diagnosis and prediction of the optimal diet, but also to point out those patients that could benefit from new therapeutic approach. They may potentially benefit from BH4 therapy which, combined with a less strict diet, or eventually in special cases as monotherapy, may contribute to reduce nutritional deficiencies and minimize neurological and psychological dysfunctions.
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Affiliation(s)
- Roberta Trunzo
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy.
| | - Rosa Santacroce
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Giovanna D'Andrea
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Vittoria Longo
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Giuseppe De Girolamo
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Claudia Dimatteo
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Angelica Leccese
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | - Valeria Bafunno
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
| | | | | | - Maurizio Margaglione
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia, Italy
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Al Hafid N, Christodoulou J. Phenylketonuria: a review of current and future treatments. Transl Pediatr 2015; 4:304-17. [PMID: 26835392 PMCID: PMC4728993 DOI: 10.3978/j.issn.2224-4336.2015.10.07] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 10/26/2015] [Indexed: 01/16/2023] Open
Abstract
Phenylketonuria (PKU) is an autosomal recessive inborn error of metabolism caused by a deficiency in the hepatic enzyme phenylalanine hydroxylase (PAH). If left untreated, the main clinical feature is intellectual disability. Treatment, which includes a low Phe diet supplemented with amino acid formulas, commences soon after diagnosis within the first weeks of life. Although dietary treatment has been successful in preventing intellectual disability in early treated PKU patients, there are major issues with dietary compliance due to palatability of the diet. Other potential issues associated with dietary therapy include nutritional deficiencies especially vitamin D and B12. Suboptimal outcomes in cognitive and executive functioning have been reported in patients who adhere poorly to dietary therapy. There have been continuous attempts at improving the quality of medical foods including their palatability. Advances in dietary therapy such as the use of large neutral amino acids (LNAA) and glycomacropeptides (GMP; found within the whey fraction of bovine milk) have been explored. Gene therapy and enzyme replacement or substitution therapy have yielded more promising data in the recent years. In this review the current and possible future treatments for PKU are discussed.
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Reitzle L, Maier B, Stojanov S, Teupser D, Muntau AC, Vogeser M, Gersting SW. Quantification of mevalonate-5-phosphate using UPLC-MS/MS for determination of mevalonate kinase activity. Clin Biochem 2015; 48:781-7. [DOI: 10.1016/j.clinbiochem.2015.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/19/2015] [Accepted: 05/06/2015] [Indexed: 10/23/2022]
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Reverter E, Mesonero F, Seijo S, Martínez J, Abraldes JG, Peñas B, Berzigotti A, Deulofeu R, Bosch J, Albillos A, García-Pagán JC. Effects of Sapropterin on Portal and Systemic Hemodynamics in Patients With Cirrhosis and Portal Hypertension: A Bicentric Double-Blind Placebo-Controlled Study. Am J Gastroenterol 2015; 110:985-92. [PMID: 26077176 DOI: 10.1038/ajg.2015.185] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/03/2015] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Tetrahydrobiopterin (BH4), a cofactor of nitric oxide synthase, might have a role in the treatment of portal hypertension (PHT) as its administration improves endothelial nitric oxide generation and hepatic endothelial dysfunction, and reduces portal pressure in experimental models of cirrhosis. Sapropterin is an oral synthetic analogue of BH4 recently approved for the treatment of phenylketonuria. This study evaluated the safety and effects of sapropterin on hepatic and systemic hemodynamics in patients with cirrhosis and PHT. METHODS Forty patients with cirrhosis and PHT (hepatic venous pressure gradient (HVPG) ≥10 mm Hg) were randomly allocated to receive sapropterin (n=19) for 2 weeks (5 mg/kg/day increased to 10 at day 8) or placebo (n=21) in a double-blind multicenter clinical trial. Randomization was stratified according to concomitant treatment with β-adrenergic blockers. We studied at baseline and post-treatment splanchnic (HVPG and hepatic blood flow (HBF)) and systemic hemodynamics, endothelial dysfunction and oxidative stress markers (von Willebrand factor and malondialdehyde), liver function tests, and safety variables. RESULTS HVPG was not modified by either sapropterin (16.0±4.4 vs. 15.8±4.7 mm Hg) or placebo (16.0±4.6 vs. 15.5±4.9 mm Hg). HBF, systemic hemodynamics, endothelial dysfunction markers, and liver function tests remained unchanged. Sapropterin was well tolerated (no patient required dose adjustment or withdrawal), and adverse events were mild and similar between groups. CONCLUSIONS Sapropterin, an oral synthetic analogue of BH4, at the used dose did not reduce portal pressure in patients with cirrhosis. Sapropterin was safe and no serious adverse effects or deleterious systemic hemodynamic effects were observed.
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Affiliation(s)
- Enric Reverter
- 1] Barcelona Hepatic Hemodynamic Laboratory, Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain [2] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain
| | - Francisco Mesonero
- 1] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain [2] Gastroenterology and Hepatology, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria, University of Alcalá, Madrid, Spain
| | - Susana Seijo
- 1] Barcelona Hepatic Hemodynamic Laboratory, Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain [2] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain
| | - Javier Martínez
- 1] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain [2] Gastroenterology and Hepatology, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria, University of Alcalá, Madrid, Spain
| | - Juan G Abraldes
- 1] Barcelona Hepatic Hemodynamic Laboratory, Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain [2] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain
| | - Beatriz Peñas
- 1] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain [2] Gastroenterology and Hepatology, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria, University of Alcalá, Madrid, Spain
| | - Annalisa Berzigotti
- 1] Barcelona Hepatic Hemodynamic Laboratory, Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain [2] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain
| | - Ramon Deulofeu
- 1] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain [2] Department of Biochemistry and Molecular Genetics, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain
| | - Jaume Bosch
- 1] Barcelona Hepatic Hemodynamic Laboratory, Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain [2] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain
| | - Agustín Albillos
- 1] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain [2] Gastroenterology and Hepatology, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria, University of Alcalá, Madrid, Spain
| | - Joan Carles García-Pagán
- 1] Barcelona Hepatic Hemodynamic Laboratory, Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain [2] Centro de Investigaciones Biomédicas en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Madrid, Spain
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