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Çıkı K, Yıldız Y, Kahraman AB, Özgül RK, Coşkun T, Dursun A, Tokatlı A, Sivri S. Predictors of eventual requirement of phenylalanine-restricted diet in young infants with phenylalanine hydroxylase deficiency initially managed with sapropterin monotherapy. Mol Genet Metab 2023; 140:107706. [PMID: 37837865 DOI: 10.1016/j.ymgme.2023.107706] [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: 08/20/2023] [Revised: 10/02/2023] [Accepted: 10/02/2023] [Indexed: 10/16/2023]
Abstract
BACKGROUND Phenylalanine (Phe)-restricted diet is associated with lower quality of life for patients with phenylketonuria (PKU), and a concern for caregivers of recently-diagnosed infants. Sapropterin is an oral drug used as an alternative or adjunct to dietary treatment. We have observed that some of the young infants initially managed successfully with sapropterin monotherapy have required dietary treatment in long-term follow-up. We aimed to determine the baseline factors associated with future initiation of dietary treatment in these patients. METHODS Data were obtained retrospectively from the medical records of 80 PKU patients started on sapropterin monotherapy before 3 months of age between 2011 and 2021. RESULTS The patients were followed for a median of 3.9 years (Q1-Q3: 2.5-5.75 years). Sapropterin was tapered down and discontinued in 5 patients (6.3%) as their Phe levels remained below 360 μmol/L without treatment. Sapropterin monotherapy was sufficient in 62 patients (77.5%), while 13 (16.2%) required dietary treatment. Phe and tyrosine (Tyr) levels, and Phe:Tyr ratios differed significantly among the patients maintained on sapropterin monotherapy and those started on dietary treatment, but the Phe:Tyr ratio at diagnosis was the most important independent baseline variable (OR: 1.61, 95% CI: 1.15-2.27, p = 0.006), with Phe:Tyr ratio at diagnosis >5.25 associated with dietary treatment (sensitivity: 90.0%, specificity: 81.8%). Genotypic phenotype value (GPV), unavailable at baseline, was also associated with dietary treatment (median GPV 9.2 vs. 3.8, p = 0.006), but some genotypes were not specific to the final treatment modality. DISCUSSION We propose that the Phe:Tyr ratio at diagnosis is an important indicator to predict dietary requirement in young infants initially managed with sapropterin monotherapy.
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Affiliation(s)
- Kısmet Çıkı
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Yılmaz Yıldız
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Ayça Burcu Kahraman
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - R Köksal Özgül
- Hacettepe University Institute of Child Health, Ankara, Turkey.
| | - Turgay Coşkun
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Ali Dursun
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Ayşegül Tokatlı
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Serap Sivri
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
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Takano C, Grubbs BH, Ishige M, Ogawa E, Morioka I, Hayakawa S, Miki T. Clinical perspective on the use of human amniotic epithelial cells to treat congenital metabolic diseases with a focus on maple syrup urine disease. Stem Cells Transl Med 2021; 10:829-835. [PMID: 33547875 PMCID: PMC8133340 DOI: 10.1002/sctm.20-0225] [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: 09/23/2020] [Revised: 12/18/2020] [Accepted: 12/20/2020] [Indexed: 12/16/2022] Open
Abstract
Congenital metabolic diseases are a group of hereditary disorders caused by the deficiency of a single specific enzyme activity. Without appropriate therapy, affected patients suffer severe neurologic disability and eventual death. The current mainstays of management attempt to slow disease progression, but are not curative. Several of these diseases have demonstrated significant benefits from liver transplantation; however, this approach is limited by the morbidity associated with this invasive procedure and a shortage of donor organs. Therefore, there is a need to establish a new strategy for improving the quality of a life for these patients. One potential solution is regenerative therapy using hepatocytes generated from stem cells. Herein, we discuss pertinent issues necessary for clinical application of the human amniotic epithelial cell, a type of placental stem cell. Focusing on maple syrup urine disease as an example, where liver replacement is an effective therapy, we explore this approach from a clinician's perspective.
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Affiliation(s)
- Chika Takano
- Division of Microbiology, Department of Pathology and MicrobiologyNihon University School of MedicineTokyoJapan
- Department of Pediatrics and Child HealthNihon University School of MedicineTokyoJapan
| | - Brendan H. Grubbs
- Department of Obstetrics and GynecologyKeck School of Medicine, University of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Mika Ishige
- Department of Pediatrics and Child HealthNihon University School of MedicineTokyoJapan
| | - Erika Ogawa
- Department of Pediatrics and Child HealthNihon University School of MedicineTokyoJapan
| | - Ichiro Morioka
- Department of Pediatrics and Child HealthNihon University School of MedicineTokyoJapan
| | - Satoshi Hayakawa
- Division of Microbiology, Department of Pathology and MicrobiologyNihon University School of MedicineTokyoJapan
| | - Toshio Miki
- Department of PhysiologyNihon University School of MedicineTokyoJapan
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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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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: 421] [Impact Index Per Article: 60.1] [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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Trefz F, Lichtenberger O, Blau N, Muntau AC, Feillet F, Bélanger-Quintana A, van Spronsen F, Munafo A. Tetrahydrobiopterin (BH4) responsiveness in neonates with hyperphenylalaninemia: a semi-mechanistically-based, nonlinear mixed-effect modeling. Mol Genet Metab 2015; 114:564-9. [PMID: 25726095 DOI: 10.1016/j.ymgme.2015.01.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 01/29/2015] [Accepted: 01/29/2015] [Indexed: 11/30/2022]
Abstract
Neonatal loading studies with tetrahydrobiopterin (BH4) are used to detect hyperphenylalaninemia due to BH4 deficiency by evaluating decreases in blood phenylalanine (Phe) concentrations post BH4 load. BH4 responsiveness in phenylalanine hydroxylase (PAH)-deficient patients introduced a new diagnostic aspect for this test. In older children, a broad spectrum of different levels of responsiveness has been described. The primary objective of this study was to develop a pharmacodynamic model to improve the description of individual sensitivity to BH4 in the neonatal period. Secondary objectives were to evaluate BH4 responsiveness in a large number of PAH-deficient patients from a neonatal screening program and in patients with various confirmed BH4 deficiencies from the BIODEF database. Descriptive statistics in patients with PAH deficiency with 0-24-h data available showed that 129 of 340 patients (37.9%) had a >30% decrease in Phe levels post load. Patients with dihydropteridine reductase deficiency (n = 53) could not be differentiated from BH4-responsive patients with PAH deficiency. The pharmacologic turnover model, "stimulation of loss" of Phe following BH4 load, fitted the data best. Using the model, 193 of 194 (99.5%) patients with a proven BH4 synthesis deficiency or recycling defect were classified as BH4 sensitive. Among patients with PAH deficiency, 216 of 375 (57.6%) patients showed sensitivity to BH4, albeit with a pronounced variability; PAH-deficient patients with blood Phe <1200 μmol/L at time 0 showed higher sensitivity than patients with blood Phe levels >1200 μmol/L. External validation showed good correlation between the present approach, using 0-24-h blood Phe data, and the published 48-h prognostic test. Pharmacodynamic modeling of Phe levels following a BH4 loading test is sufficiently powerful to detect a wide range of responsiveness, interpretable as a measure of sensitivity to BH4. However, the clinical relevance of small responses needs to be evaluated by further studies of their relationship to long-term response to BH4 treatment.
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Affiliation(s)
- Friedrich Trefz
- Outpatient Medical Centre for Women, Children and Adolescents, Kreiskliniken Reutlingen GmbH, 72501 Gammertingen, Marktstrasse 4, Germany.
| | | | - Nenad Blau
- University Children's Hospital, Im Neuenheimer Feld 430, 69120 Heidelberg, Germany.
| | - Ania C Muntau
- University Children's Hospital, Medical Center Hamburg Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
| | - Francois Feillet
- Reference Centre for Inborn Metabolic Diseases, Pediatric Unit, Children's Hospital, CHU Brabois, Allée du Morvan, 54511 Vandoeuvre les Nancy, France.
| | - Amaya Bélanger-Quintana
- Unidad de Enfermedades Metabolicas, Servicio de Pediatria, Hospital Ramon y Cajal, Crta Colmenar km 9, 1 Madrid 28034, Spain.
| | - Francjan van Spronsen
- Beatrix Children's Hospital, University Medical Center of Groningen, University of Groningen, Groningen, The Netherlands.
| | - Alain Munafo
- Merck Institute for Pharmacometrics, Merck Serono S.A., EPFL Innovation Park - Building I, CH-1015 Lausanne, Switzerland.
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Stockler-Ipsiroglu S, Yuskiv N, Salvarinova R, Apatean D, Ho G, Cheng B, Giezen A, Lillquist Y, Ueda K. Individualized long-term outcomes in blood phenylalanine concentrations and dietary phenylalanine tolerance in 11 patients with primary phenylalanine hydroxylase (PAH) deficiency treated with Sapropterin-dihydrochloride. Mol Genet Metab 2015; 114:409-14. [PMID: 25497838 DOI: 10.1016/j.ymgme.2014.11.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/20/2014] [Accepted: 11/20/2014] [Indexed: 10/24/2022]
Abstract
We analyzed long-term sustainability of improved blood Phenylalanine (Phe) control and changes to dietary Phe tolerance in 11 patients (1 month to 16 years), with various forms of primary PAH deficiency (classic, moderate, severe phenylketonuria [PKU], mild hyperphenylalaninemia [HPA]), who were treated with 15-20mg/kg/d Sapropterin-dihydrochloride during a period of 13-44 months. 7/11 patients had a sustainable, significant reduction of baseline blood Phe concentrations and 6 of them also had an increase in mg/kg/day Phe tolerance. In 2 patients with mild HPA, blood Phe concentrations remained in the physiologic range even after a 22 and 36% increase in mg/kg/day Phe tolerance and an achieved Phe intake at 105% and 268% of the dietary reference intake (DRI) for protein. 2 of these responders had classic PKU. 1 patient with mild HPA who started treatment at 2 months of life, had a significant and sustainable reduction in pretreatment blood Phe concentrations, but no increase in the mg/kg/day Phe tolerance. An increase in Phe tolerance could only be demonstrated when expressing the patient's daily Phe tolerance with the DRI for protein showing an increase from 58% at baseline to 78% of normal DRI at the end of the observation. Long-term follow-up of patients with an initial response to treatment with Sapropterin is essential to determine clinically meaningful outcomes. Phenylalanine tolerance should be expressed in mg/kg/day and/or % of normal DRI to differentiate medical therapy related from physiologic growth related increase in daily Phe intake.
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Affiliation(s)
- Sylvia Stockler-Ipsiroglu
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada.
| | - Nataliya Yuskiv
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada
| | - Ramona Salvarinova
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada
| | - Delia Apatean
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada
| | - Gloria Ho
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada
| | - Barbara Cheng
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada
| | - Alette Giezen
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada
| | - Yolanda Lillquist
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada
| | - Keiko Ueda
- Department of Pediatrics, University of British Columbia, Division of Biochemical Diseases, British Columbia Children's Hospital, Vancouver, Canada
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Scala I, Concolino D, Della Casa R, Nastasi A, Ungaro C, Paladino S, Capaldo B, Ruoppolo M, Daniele A, Bonapace G, Strisciuglio P, Parenti G, Andria G. Long-term follow-up of patients with phenylketonuria treated with tetrahydrobiopterin: a seven years experience. Orphanet J Rare Dis 2015; 10:14. [PMID: 25757997 PMCID: PMC4351928 DOI: 10.1186/s13023-015-0227-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 01/15/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Phenylketonuria (PKU) is an autosomal recessive disorder caused by the deficiency of phenylalanine hydroxylase that catalyzes the conversion of phenylalanine to tyrosine, using tetrahydrobiopterin (BH4) as coenzyme. Besides dietary phenylalanine restriction, new therapeutic options are emerging, such as the treatment with BH4 in subgroups of PKU patients responding to a loading test with BH4. METHODS A no-profit open-label interventional trial with long-term oral BH4 therapy, sponsored by the Italian Medicines Agency (AIFA), was performed in a group of 17 PKU patients resulted as BH4 responders among 46 subjects analyzed for BH4-responsiveness (prot. FARM5MATC7). We report on efficacy and safety data of BH4 therapy and analyze factors predicting BH4-responsiveness and long-term response to BH4. A BH4-withdrawal test was used as a proof of the efficacy of long-term therapy with BH4. RESULTS Forty-four percent of the patients responded to the 48 h-long loading test with BH4. All the phenotypic classes were represented. Genotype was the best predictor of responsiveness, along with lower phenylalanine levels at diagnosis, higher tolerance and lower phenylalanine/tyrosine ratio before the test. In BH4 responder patients, long-term BH4 therapy resulted safe and effective in increasing tolerance while maintaining a good metabolic control. The BH4 withdrawal test, performed in a subset of patients, showed that improved tolerance was directly dependent on BH4 assumption. Tolerance to phenylalanine was re-evaluated in 43.5% of patients and was longitudinally analyzed in 5 patients. CONCLUSIONS Long-term treatment with BH4 is safe and effective in increasing tolerance to phenylalanine. There is real need to assess the actual tolerance to phenylalanine in PKU patients to ameliorate quality of life, improve nutritional status, avoiding unnecessarily restricted diets, and interpret the effects of new therapies for PKU.
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Affiliation(s)
- Iris Scala
- Department of Translational Medicine-Section of Pediatrics, Federico II University, Via S. Pansini 5, 80131, Naples, Italy.
| | - Daniela Concolino
- Department of Pediatrics, Magna Graecia University, Catanzaro, Italy.
| | - Roberto Della Casa
- Department of Translational Medicine-Section of Pediatrics, Federico II University, Via S. Pansini 5, 80131, Naples, Italy.
| | - Anna Nastasi
- Department of Clinical Medicine and Surgery, Physiology Nutrition Unit, Federico II University, Naples, Italy.
| | - Carla Ungaro
- Department of Translational Medicine-Section of Pediatrics, Federico II University, Via S. Pansini 5, 80131, Naples, Italy.
| | - Serena Paladino
- Department of Translational Medicine-Section of Pediatrics, Federico II University, Via S. Pansini 5, 80131, Naples, Italy.
| | - Brunella Capaldo
- Department of Clinical Medicine and Surgery, Federico II University, Naples, Italy.
| | - Margherita Ruoppolo
- Department of Molecular Medicine and Medical Biotechnology, Federico II University, Naples, Italy.
- CEINGE-Biotecnologie Avanzate s.c.ar.l., Naples, Italy.
| | - Aurora Daniele
- CEINGE-Biotecnologie Avanzate s.c.ar.l., Naples, Italy.
- Dipartimento di Scienze e Tecnologie Ambientali Biologiche Farmaceutiche, Seconda Università degli Studi di Napoli, Caserta, Italy.
| | - Giuseppe Bonapace
- Department of Pediatrics, Magna Graecia University, Catanzaro, Italy.
| | - Pietro Strisciuglio
- Department of Translational Medicine-Section of Pediatrics, Federico II University, Via S. Pansini 5, 80131, Naples, Italy.
| | - Giancarlo Parenti
- Department of Translational Medicine-Section of Pediatrics, Federico II University, Via S. Pansini 5, 80131, Naples, Italy.
| | - Generoso Andria
- Department of Translational Medicine-Section of Pediatrics, Federico II University, Via S. Pansini 5, 80131, Naples, Italy.
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Cleary M, Trefz F, Muntau AC, Feillet F, van Spronsen FJ, Burlina A, Bélanger-Quintana A, Giżewska M, Gasteyger C, Bettiol E, Blau N, MacDonald A. Fluctuations in phenylalanine concentrations in phenylketonuria: a review of possible relationships with outcomes. Mol Genet Metab 2013; 110:418-23. [PMID: 24090706 DOI: 10.1016/j.ymgme.2013.09.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 09/03/2013] [Indexed: 11/21/2022]
Abstract
Fluctuations in blood phenylalanine concentrations may be an important determinant of intellectual outcome in patients with early and continuously treated phenylketonuria (PKU). This review evaluates the studies on phenylalanine fluctuations, factors affecting fluctuations, and if stabilizing phenylalanine concentrations affects outcomes, particularly neurocognitive outcome. Electronic literature searches of Embase and PubMed were performed for English-language publications, and the bibliographies of identified publications were also searched. In patients with PKU, phenylalanine concentrations are highest in the morning. Factors that can affect phenylalanine fluctuations include age, diet, timing and dosing of protein substitute and energy intake, dietary adherence, phenylalanine hydroxylase genotype, changes in dietary phenylalanine intake and protein metabolism, illness, and growth rate. Even distribution of phenylalanine-free protein substitute intake throughout 24h may reduce blood phenylalanine fluctuations. Patients responsive to and treated with 6R-tetrahydrobiopterin seem to have less fluctuation in their blood phenylalanine concentrations than controls. An increase in blood phenylalanine concentration may result in increased brain and cerebrospinal fluid phenylalanine concentrations within hours. Although some evidence suggests that stabilization of blood phenylalanine concentrations may have benefits in patients with PKU, more studies are needed to distinguish the effects of blood phenylalanine fluctuations from those of poor metabolic control.
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Affiliation(s)
- Maureen Cleary
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.
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Anjema K, van Rijn M, Hofstede FC, Bosch AM, Hollak CEM, Rubio-Gozalbo E, de Vries MC, Janssen MCH, Boelen CCA, Burgerhof JGM, Blau N, Heiner-Fokkema MR, van Spronsen FJ. Tetrahydrobiopterin responsiveness in phenylketonuria: prediction with the 48-hour loading test and genotype. Orphanet J Rare Dis 2013; 8:103. [PMID: 23842451 PMCID: PMC3711849 DOI: 10.1186/1750-1172-8-103] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 07/01/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND How to efficiently diagnose tetrahydrobiopterin (BH4) responsiveness in patients with phenylketonuria remains unclear. This study investigated the positive predictive value (PPV) of the 48-hour BH4 loading test and the additional value of genotype. METHODS Data of the 48-hour BH4 loading test (20 mg BH4/kg/day) were collected at six Dutch university hospitals. Patients with ≥30% phenylalanine reduction at ≥1 time points during the 48 hours (potential responders) were invited for the BH4 extension phase, designed to establish true-positive BH4 responsiveness. This is defined as long-term ≥30% reduction in mean phenylalanine concentration and/or ≥4 g/day and/or ≥50% increase of natural protein intake. Genotype was collected if available. RESULTS 177/183 patients successfully completed the 48-hour BH4 loading test. 80/177 were potential responders and 67/80 completed the BH4 extension phase. In 58/67 true-positive BH4 responsiveness was confirmed (PPV 87%). The genotype was available for 120/177 patients. 41/44 patients with ≥1 mutation associated with long-term BH4 responsiveness showed potential BH4 responsiveness in the 48-hour test and 34/41 completed the BH4 extension phase. In 33/34 true-positive BH4 responsiveness was confirmed. 4/40 patients with two known putative null mutations were potential responders; 2/4 performed the BH4 extension phase but showed no true-positive BH4 responsiveness. CONCLUSIONS The 48-hour BH4 loading test in combination with a classified genotype is a good parameter in predicting true-positive BH4 responsiveness. We propose assessing genotype first, particularly in the neonatal period. Patients with two known putative null mutations can be excluded from BH4 testing.
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Affiliation(s)
- Karen Anjema
- Division of Metabolic Diseases, University Medical Center Groningen, Beatrix Children’s Hospital CA33, PO box 30.001, Groningen 9700 RB, The Netherlands
| | - Margreet van Rijn
- Division of Metabolic Diseases, University Medical Center Groningen, Beatrix Children’s Hospital CA33, PO box 30.001, Groningen 9700 RB, The Netherlands
| | - Floris C Hofstede
- University Medical Center Utrecht, Wilhelmina Children’s Hospital, Utrecht, The Netherlands
| | - Annet M Bosch
- Academic Medical Center, University Hospital of Amsterdam, Amsterdam, The Netherlands
| | - Carla EM Hollak
- Academic Medical Center, University Hospital of Amsterdam, Amsterdam, The Netherlands
| | | | - Maaike C de Vries
- Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Mirian CH Janssen
- Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | | | - Johannes GM Burgerhof
- Division of Metabolic Diseases, University Medical Center Groningen, Beatrix Children’s Hospital CA33, PO box 30.001, Groningen 9700 RB, The Netherlands
| | - Nenad Blau
- University Children’s Hospital, Heidelberg, Germany
- University Children’s Hospital, Zürich, Switzerland
| | - M Rebecca Heiner-Fokkema
- Division of Metabolic Diseases, University Medical Center Groningen, Beatrix Children’s Hospital CA33, PO box 30.001, Groningen 9700 RB, The Netherlands
| | - Francjan J van Spronsen
- Division of Metabolic Diseases, University Medical Center Groningen, Beatrix Children’s Hospital CA33, PO box 30.001, Groningen 9700 RB, The Netherlands
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10
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Hennermann JB, Roloff S, Gebauer C, Vetter B, von Arnim-Baas A, Mönch E. Long-term treatment with tetrahydrobiopterin in phenylketonuria: treatment strategies and prediction of long-term responders. Mol Genet Metab 2012; 107:294-301. [PMID: 23062575 DOI: 10.1016/j.ymgme.2012.09.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 09/21/2012] [Accepted: 09/21/2012] [Indexed: 10/27/2022]
Abstract
Tetrahydrobiopterin (BH4) responsive phenylketonuria has been described more than 10 years ago. However, criteria for the identification of long-term BH4 responsive patients are not yet established. 116 patients with phenylketonuria, aged 4-18 years, were screened for potential long-term BH4 responsiveness by at least two of the following criteria: positive neonatal BH4 loading test, putative BH4 responsive genotype, and/or milder phenotype. Patients had to be on permanent dietary treatment. 23 patients fulfilled these criteria and were tested for long-term BH4 responsiveness: 18/23 were long-term BH4 responsive, 5/23 were not. On long-term BH4 treatment over a period of 48 ± 27 months in a dose of 14.9 ± 3.3mg/kg/day phenylalanine tolerance was increased from 452 ± 201 mg/day to 1593 ± 647 mg/day, corresponding to a mean increase of 1141 ± 528 mg/day. Dietary phenylalanine intake was increased stepwise according to a clear defined protocol. In 8/18 patients, diet was completely liberalized; 10/18 patients still received phenylalanine-free amino acid formula with 0.63 ± 0.23 g/kg/day. The most predictive value for long-term BH4 responsiveness was the combination of pretreatment phenylalanine of < 1200 μmol/L, pretreatment phenylalanine/tyrosine ratio of <15, phenylalanine/tyrosine ratio of <15 on treatment, phenylalanine tolerance of >20mg/kg/day at age 3 years, positive neonatal BH4 loading, and at least one putative BH4 responsive mutation (p = 0.00024). Our data show that long-term BH4 responsiveness may be predicted already during neonatal period by determining maximum pretreatment phenylalanine and phenylalanine/tyrosine concentrations, neonatal BH4 loading and PAH genotype. A clear defined protocol is necessary to install long-term BH4 treatment.
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Affiliation(s)
- Julia B Hennermann
- Otto Heubner Center for Pediatric and Adolescent Medicine, Charité Universitätsmedizin Berlin, Germany.
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11
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Quirk ME, Dobrowolski SF, Nelson BE, Coffee B, Singh RH. Utility of phenylalanine hydroxylase genotype for tetrahydrobiopterin responsiveness classification in patients with phenylketonuria. Mol Genet Metab 2012; 107:31-6. [PMID: 22841515 PMCID: PMC4029439 DOI: 10.1016/j.ymgme.2012.07.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/10/2012] [Accepted: 07/11/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND A need exists to expand the characterization of tetrahydrobiopterin (BH(4)) responsiveness in patients with phenylketonuria (PKU), beyond simply evaluating change in blood phenylalanine concentrations. The clinical interpretation of BH(4) responsiveness should be evaluated within the context of phenylalanine hydroxylase (PAH) genotype. AIM This investigation seeks to use a modified version of a previously developed PAH genotype severity tool, the assigned value (AV) sum, to assess the molecular basis of responsiveness in a clinical cohort and to explore the tool's ability to differentiate BH(4) responsive groups. METHODS BH(4) response was previously clinically classified in 58 patients with PKU, with three response groups emerging: definitive responders, provisional responders, and non-responders. Provisional responders represented a clinically ambiguous group, with an initial decrease in plasma phenylalanine concentrations, but limited ability to improve dietary phenylalanine tolerance. In this retrospective analysis, mutations in the PAH gene were identified in each patient. PAH genotype was characterized through the AV sum approach, in which each mutation is given an AV of 1, 2, 4, or 8; the sum of both mutations' AV corresponds to genotype severity, with a lower number representing a more severe phenotype. An AV sum cutoff of 2 (indicative of the most severe genotypes) was used to dichotomize patients and predict BH(4) responsiveness. Provisional responders were classified with the definitive responders then the non-responders to see with which group they best aligned. RESULTS In 17/19 definitive responders, at least one mutation was mild or moderate in severity (AV sum>2). In contrast, 7/9 provisional responders carried two severe or null mutations (AV sum=2), suggesting little molecular basis for responsiveness. Non-responders represent a heterogeneous group with 15/25 patients carrying two severe mutations (AV sum=2), 5/25 patients carrying one moderate or mild mutation in combination with a severe or null mutation (AV sum>2), and the remaining five patients carrying an uncharacterized mutation in combination with a severe mutation. Predictive sensitivity of the AV sum was maximized (89.5% vs. 67.9%) with limited detriment to specificity (79.4% vs. 80.0%), by classifying provisional responders with the non-responders rather than with the definitive responders. CONCLUSIONS In our clinical cohort, the AV sum tool was able to identify definitive responders with a high degree of sensitivity. As demonstrated by both the provisional responder group and the substantial number of non-responders with AV sums>2, a potential exists for misclassification when BH(4) response is determined by relying solely on change in plasma phenylalanine concentrations. PAH genotype should be incorporated in the clinical evaluation of BH(4) responsiveness.
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Affiliation(s)
- Meghan E. Quirk
- Division of Biological and Biomedical Sciences, Nutrition and Health Sciences, Emory University, Atlanta, GA, USA
| | - Steven F. Dobrowolski
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | | | - Bradford Coffee
- Department of Human Genetics, Emory University School of Medicine, Decatur, GA, USA
| | - Rani H. Singh
- Division of Biological and Biomedical Sciences, Nutrition and Health Sciences, Emory University, Atlanta, GA, USA
- Department of Human Genetics, Emory University School of Medicine, Decatur, GA, USA
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12
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Lindegren ML, Krishnaswami S, Reimschisel T, Fonnesbeck C, Sathe NA, McPheeters ML. A Systematic Review of BH4 (Sapropterin) for the Adjuvant Treatment of Phenylketonuria. JIMD Rep 2012; 8:109-19. [PMID: 23430527 DOI: 10.1007/8904_2012_168] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 06/20/2012] [Accepted: 07/04/2012] [Indexed: 12/04/2022] Open
Abstract
CONTEXT Dietary management is the mainstay of effective treatment in PKU, but dietary restriction is difficult and additional treatment options are needed. OBJECTIVE To systematically review evidence regarding sapropterin (BH4) use as an adjunct to dietary restriction in individuals with PKU. DATA SOURCES Five databases including MEDLINE up to August 2011. STUDY SELECTION Two reviewers independently assessed studies against predetermined inclusion/exclusion criteria. DATA EXTRACTION Two reviewers independently extracted data regarding participant and intervention characteristics and outcomes and assigned overall quality and strength of evidence ratings based on predetermined criteria. RESULTS BH4 research includes two randomized controlled trials (RCTs) and three uncontrolled open-label trials. Phenylalanine (Phe) levels were reduced by at least 30 % in up to half of treated participants (32-50 %). In one RCT comparing placebo on likelihood of a 30 % reduction in Phe, 9 % of those on placebo achieved this effect, compared with 44 % of the treated group after 6 weeks. Phe tolerance and variability were improved in treated participants in studies assessing those outcomes. No comparative studies assessed long-term outcomes including cognitive effects, nutritional status, or quality of life. CONCLUSIONS Adjuvant pharmacologic therapy has the potential to support individuals in achieving optimal Phe levels. BH4 has been shown to reduce Phe levels in some individuals, with significantly greater reductions seen in treated versus placebo groups. The strength of the evidence is moderate for short-term effects on reducing Phe in a subset of initially BH4-responsive individuals, moderate for a lack of significant harms, low for longer-term effects on cognition, and insufficient for all other outcomes.
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Affiliation(s)
- Mary Lou Lindegren
- Division of General Pediatrics and Vanderbilt Institute for Global Health, Vanderbilt Medical Center, 2200 Children's Way, 8232 Doctors' Office Tower, Nashville, TN, 37232-9225, USA,
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13
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Robertson NJ, Tan S, Groenendaal F, van Bel F, Juul SE, Bennet L, Derrick M, Back SA, Valdez RC, Northington F, Gunn AJ, Mallard C. Which neuroprotective agents are ready for bench to bedside translation in the newborn infant? J Pediatr 2012; 160:544-552.e4. [PMID: 22325255 PMCID: PMC4048707 DOI: 10.1016/j.jpeds.2011.12.052] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 12/02/2011] [Accepted: 12/30/2011] [Indexed: 02/07/2023]
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14
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Sarkissian CN, Gamez A, Scott P, Dauvillier J, Dorenbaum A, Scriver CR, Stevens RC. Chaperone-like therapy with tetrahydrobiopterin in clinical trials for phenylketonuria: is genotype a predictor of response? JIMD Rep 2011; 5:59-70. [PMID: 23430918 DOI: 10.1007/8904_2011_96] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 08/04/2011] [Accepted: 09/20/2011] [Indexed: 12/24/2022] Open
Abstract
Prospectively enrolled phenylketonuria patients (n=485) participated in an international Phase II clinical trial to identify the prevalence of a therapeutic response to daily doses of sapropterin dihydrochloride (sapropterin, KUVAN(®)). Responsive patients were then enrolled in two subsequent Phase III clinical trials to examine safety, ability to reduce blood Phenylalanine levels, dosage (5-20 mg/kg/day) and response, and bioavailability of sapropterin. We combined phenotypic findings in the Phase II and III clinical trials to classify study-related responsiveness associated with specific alleles and genotypes identified in the patients. We found that 17% of patients showed a response to sapropterin. The patients harbored 245 different genotypes derived from 122 different alleles, among which ten alleles were newly discovered. Only 16.3% of the genotypes clearly conferred a sapropterin-responsive phenotype. Among the different PAH alleles, only 5% conferred a responsive phenotype. The responsive alleles were largely but not solely missense mutations known to or likely to cause misfolding of the PAH subunit. However, the metabolic response was not robustly predictable from the PAH genotypes, based on the study design adopted for these clinical trials, and accordingly it seems prudent to test each person for this phenotype with a standardized protocol.
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Affiliation(s)
- Christineh N Sarkissian
- Departments of Biology, Human Genetics and Pediatrics, McGill University, Montreal, QC, Canada
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15
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Singh RH, Quirk ME. Using change in plasma phenylalanine concentrations and ability to liberalize diet to classify responsiveness to tetrahydrobiopterin therapy in patients with phenylketonuria. Mol Genet Metab 2011; 104:485-91. [PMID: 21986447 PMCID: PMC4029441 DOI: 10.1016/j.ymgme.2011.09.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 09/08/2011] [Accepted: 09/08/2011] [Indexed: 10/17/2022]
Abstract
Tetrahydrobiopterin (BH(4)) responsiveness is currently defined as a decrease in plasma phenylalanine concentrations in patients with phenylketonuria (PKU). This definition does not offer insight beyond the initial assessment of patients, which may lead to treatment ambiguity in patients who only experience an initial decrease in plasma phenylalanine concentrations. We present our experience with a novel classification approach using sequentially-applied criteria. Plasma phenylalanine concentrations were measured at baseline and after one month of BH(4) therapy (20 mg/kg/day) in 58 PKU patients (34 M, 24 F; age 17.3±11.0 years). Thirty-two patients (55.2%) were classified as "preliminary responders" at one month, experiencing at least a 15% decrease in plasma phenylalanine concentrations. Preliminary responders' ability to liberalize their dietary restrictions was then systematically assessed. "Definitive responders" were defined as preliminary responders who could increase their dietary phenylalanine tolerance by at least 300 mg/day and lower prescribed medical food needs by at least 25% while maintaining metabolic control (plasma phenylalanine ≤360 μmol/L) and consuming adequate dietary protein. Preliminary responders who could not liberalize their diets according to these criteria were classified as "provisional responders." Nineteen patients (32.8% of patients initiating BH(4) therapy) met the definitive responder criteria, increasing dietary phenylalanine tolerance from 704±518 mg/day to 1922±612 mg/day and reducing medical food to 16.7±19.5% of their baseline prescription. Nine patients (15.5% of patients initiating BH(4) therapy) were classified as provisional responders, all remaining on 100% of their baseline medical food prescription. From this classification approach, a subgroup of provisionally responsive patients emerged who experienced an initial decrease in plasma phenylalanine concentrations but who could not substantially increase their dietary phenylalanine tolerance or decrease medical food needs. Diet liberalization is an essential component of BH(4)-responsiveness classification.
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Affiliation(s)
- Rani H Singh
- Department of Human Genetics, Emory University School of Medicine, Decatur, GA 30033, USA.
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16
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Long-term pharmacological management of phenylketonuria, including patients below the age of 4 years. JIMD Rep 2011; 2:91-6. [PMID: 23430859 DOI: 10.1007/8904_2011_53] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 04/06/2011] [Accepted: 04/08/2011] [Indexed: 02/22/2023] Open
Abstract
BH4 therapy is an advancement in the treatment of phenylketonuria, reducing blood phenylalanine (phe) levels and increasing tolerance to natural proteins of responding patients. We report the results of 16 patients undergoing long-term BH4 treatment. Responding patients to BH4 was usually based on 24-h loading tests; a ≥30% decrease in blood phe was considered a positive response. Weekly loading made it possible to identify an additional "slow responder." The 16 responders constitute 24.6% of patients who completed the trial (87.5% of responders in mild hyperphenylalaninemia, 38.1% in mild PKU, and 2.8% in classical PKU).Mean dose of BH4 used was 9.75 ± 0.9 mg/kg per day, during a mean of 62 months. Age at treatment start was below 4 years in seven patients; five of which begun treatment during their first month since birth. All but one patient showed good treatment compliance; six continue on BH4 monotherapy without dietary phe restriction; six showed an increase in phe tolerance of 24-55%; and in the five patients who received treatment since the neonatal period an increase in phe tolerance following the phase of maximum growth has persisted. None of the patients showed side effects except one whom vomiting at the beginning of the treatment.Testing at the time of diagnosis in the neonatal period is very appropriate, and if there is a positive response, the patient can be treated with BH4 from onset with the advantage of being able to continue breast-feeding.
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17
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Bélanger-Quintana A, Burlina A, Harding CO, Muntau AC. Up to date knowledge on different treatment strategies for phenylketonuria. Mol Genet Metab 2011; 104 Suppl:S19-25. [PMID: 21967857 PMCID: PMC4437510 DOI: 10.1016/j.ymgme.2011.08.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 07/23/2011] [Accepted: 08/05/2011] [Indexed: 11/18/2022]
Abstract
Dietary management for phenylketonuria was established over half a century ago, and has rendered an immense success in the prevention of the severe mental retardation associated with the accumulation of phenylalanine. However, the strict low-phenylalanine diet has several shortcomings, not the least of which is the burden it imposes on the patients and their families consequently frequent dietary non-compliance. Imperfect neurological outcome of patients in comparison to non-PKU individuals and nutritional deficiencies associated to the PKU diet are other important reasons to seek alternative therapies. In the last decade there has been an impressive effort in the investigation of other ways to treat PKU that might improve the outcome and quality of life of these patients. These studies have lead to the commercialization of sapropterin dihydrochloride, but there are still many questions regarding which patients to challenge with sapropterin what is the best challenge protocol and what could be the implications of this treatment in the long-term. Current human trials of PEGylated phenylalanine ammonia lyase are underway, which might render an alternative to diet for those patients non-responsive to sapropterin dihydrochloride. Preclinical investigation of gene and cell therapies for PKU is ongoing. In this manuscript, we will review the current knowledge on novel pharmacologic approaches to the treatment of phenylketonuria.
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Affiliation(s)
- Amaya Bélanger-Quintana
- Division of Metabolic Diseases, Pediatrics Department, Ramon y Cajal Hospital, Madrid, Spain.
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18
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Enns GM, Koch R, Brumm V, Blakely E, Suter R, Jurecki E. Suboptimal outcomes in patients with PKU treated early with diet alone: revisiting the evidence. Mol Genet Metab 2010; 101:99-109. [PMID: 20678948 DOI: 10.1016/j.ymgme.2010.05.017] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Revised: 05/27/2010] [Accepted: 05/28/2010] [Indexed: 11/22/2022]
Abstract
BACKGROUND The National Institute of Health (NIH) published a Consensus Statement on the screening and management of Phenylketonuria (PKU) in 2000. The panel involved in the development of this consensus statement acknowledged the lack of data regarding the potential for more subtle suboptimal outcomes and the need for further research into treatment options. In subsequent years, the approval of new treatment options for PKU and outcome data for patients treated from the newborn period by dietary therapy alone have become available. We hypothesized that a review of the PKU literature since 2000 would provide further evidence related to neurocognitive, psychosocial, and physical outcomes that could serve as a basis for reassessment of the 2000 NIH Consensus Statement. METHODS A systematic review of literature residing in PubMed, Scopus and PsychInfo was performed in order to assess the outcome data over the last decade in diet-alone early-treated PKU patients to assess the need for new recommendations and validity of older recommendations in light of new evidence. RESULTS The majority of publications (140/150) that contained primary outcome data presented at least one suboptimal outcome compared to control groups or standardized norms/reference values in at least one of the following areas: neurocognitive/psychosocial (N=60; 58 reporting suboptimal outcomes); quality of life (N=6; 4 reporting suboptimal outcomes); brain pathology (N=32; 30 reporting suboptimal outcomes); growth/nutrition (N=34; 29 reporting suboptimal outcomes); bone pathology (N=9; 9 reporting suboptimal outcomes); and/or maternal PKU (N=19; 19 reporting suboptimal outcomes). CONCLUSIONS Despite the remarkable success of public health programs that have instituted newborn screening and early introduction of dietary therapy for PKU, there is a growing body of evidence that suggests that neurocognitive, psychosocial, quality of life, growth, nutrition, bone pathology and maternal PKU outcomes are suboptimal. The time may be right for revisiting the 2000 NIH Consensus Statement in order to address a number of important issues related to PKU management, including treatment advancements for metabolic control in PKU, blood Phe variability, neurocognitive and psychological assessments, routine screening measures for nutritional biomarkers, and bone pathology.
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Affiliation(s)
- G M Enns
- Division of Medical Genetics, Department of Pediatrics, Lucile Packard Children's Hospital, Stanford University, Stanford, CA 94305-5208,USA.
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