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McWhorter N, Ndugga-Kabuye MK, Puurunen M, Ernst SL. Complications of the Low Phenylalanine Diet for Patients with Phenylketonuria and the Benefits of Increased Natural Protein. Nutrients 2022; 14:4960. [PMID: 36500989 PMCID: PMC9740314 DOI: 10.3390/nu14234960] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022] Open
Abstract
Phenylketonuria (PKU) is an inherited disorder in which phenylalanine (Phe) is not correctly metabolized leading to an abnormally high plasma Phe concentration that causes profound neurologic damage if left untreated. The mainstay of treatment for PKU has centered around limiting natural protein in the diet while supplementing with medical foods in order to prevent neurologic injury while promoting growth. This review discusses several deleterious effects of the low Phe diet along with benefits that have been reported for patients with increased natural protein intake while maintaining plasma Phe levels within treatment guidelines.
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Teruya KI, Remor E, Schwartz IVD. Factors that increase risk for poor adherence to phenylketonuria treatment in Brazilian patients. Am J Med Genet A 2021; 185:1991-2002. [PMID: 33765361 DOI: 10.1002/ajmg.a.62195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 03/06/2021] [Accepted: 03/12/2021] [Indexed: 11/09/2022]
Abstract
Neurotoxic effects caused by high phenylalanine (Phe) in patients with phenylketonuria (PKU) can be avoided through dietary treatment. However, achieving the recommended Phe levels has been a challenge. This study aimed to investigate factors associated with adherence to PKU treatment among patients followed at a medical genetics public service in southern Brazil. Twenty-nine patients (early diagnosed, n = 20; late-diagnosed, n = 9) with classical (n = 16) or mild PKU (n = 13) aged 6-34 years (16.4 ± 7.5) and 16 caregivers were included. Blood Phe levels were recorded, and assessment tools measuring barriers to treatment, IQ, knowledge about disease, treatment, and perceived adherence were collected. Classical PKU patients showed higher current blood Phe levels than mild PKU patients (U = 37.000, p = 0.003). Lifetime and childhood Phe levels were associated with recent metabolic control (τ = 0.76, p = 0.000; τ = 0.70, p = 0.000, respectively). The perception of barriers to treatment was associated with a higher blood Phe level (τ = 0.39, p = 0.003). Tolerance to Phe, metabolic control throughout childhood, and perceived difficulty in living with demands of treatment are important factors of greater vulnerability to poor adherence in PKU patients.
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Affiliation(s)
- Katia Irie Teruya
- Institute of Psychology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Eduardo Remor
- Institute of Psychology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Ida Vanessa Doederlein Schwartz
- Department of Genetics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Medical Genetics Service, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil
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Yuskiv N, Potter BK, Stockler S, Ueda K, Giezen A, Cheng B, Langley E, Ratko S, Austin V, Chapman M, Chakraborty P, Collet JP, Pender A. Nutritional management of phenylalanine hydroxylase (PAH) deficiency in pediatric patients in Canada: a survey of dietitians' current practices. Orphanet J Rare Dis 2019; 14:7. [PMID: 30621767 PMCID: PMC6323774 DOI: 10.1186/s13023-018-0978-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 12/11/2018] [Indexed: 01/03/2023] Open
Abstract
Background Phenylalanine hydroxylase (PAH) deficiency is one of 31 targeted inherited metabolic diseases (IMD) for the Canadian Inherited Metabolic Diseases Research Network (CIMDRN). Early diagnosis and initiation of treatment through newborn screening has gradually shifted treatment goals from the prevention of disabling complications to the optimization of long term outcomes. However, clinical evidence demonstrates that subtle suboptimal neurocognitive outcomes are present in the early and continuously diet-treated population with PAH deficiency. This may be attributed to variation in blood phenylalanine levels to outside treatment range and this, in turn, is possibly due to a combination of factors; disease severity, dietary noncompliance and differences in practice related to the management of PAH deficiency. One of CIMDRN’s goals is to understand current practices in the diagnosis and management of PAH deficiency in the pediatric population, from the perspective of both health care providers and patients/families. Objectives We investigated Canadian metabolic dietitians’ perspectives on the nutritional management of children with PAH deficiency, awareness of recently published North American treatment and nutritional guidelines in relation to PAH deficiency, and nutritional care practices within and outside these guidelines. Methods We invited 33 dietitians to participate in a survey, to ascertain their use of recently published guidelines and their practices in relation to the nutritional care of pediatric patients with PAH deficiency. Results We received 19 responses (59% response rate). All participants reported awareness of published guidelines for managing PAH deficiency. To classify disease severity, 89% of dietitians reported using pre-treatment blood phenylalanine (Phe) levels, alone or in combination with other factors. 74% of dietitians reported using blood Phe levels ≥360 μmol/L (6 mg/dL) as the criterion for initiating a Phe-restricted diet. All respondents considered 120-360 μmol/L (2–6 mg/dL) as the optimal treatment range for blood Phe in children 0–9 years old, but there was less agreement on blood Phe targets for older children. Most dietitians reported similar approaches to diet assessment and counseling: monitoring growth trends, use of 3 day diet records for intake analysis, individualization of diet goals, counseling patients to count grams of dietary natural protein or milligrams of dietary Phe, and monitoring blood Phe, tyrosine and ferritin. Conclusion While Canadian dietitians’ practices in managing pediatric PAH deficiency are generally aligned with those of the American College of Medical Genetics and Genomics (ACMG), and with the associated treatment and nutritional guidelines from Genetic Metabolic Dietitians International (GMDI), variation in many aspects of care reflects ongoing uncertainty and a need for robust evidence.
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Affiliation(s)
- Nataliya Yuskiv
- University of British Columbia, Vancouver, British Columbia, Canada.
| | | | - Sylvia Stockler
- University of British Columbia, Vancouver, British Columbia, Canada
| | - Keiko Ueda
- British Columbia Children's Hospital, Vancouver, British Columbia, Canada
| | - Alette Giezen
- British Columbia Children's Hospital, Vancouver, British Columbia, Canada
| | - Barbara Cheng
- British Columbia Children's Hospital, Vancouver, British Columbia, Canada
| | - Erica Langley
- Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - Suzanne Ratko
- Children's Hospital of Western Ontario, London, Ontario, Canada
| | - Valerie Austin
- The Hospital for Sick Children (SickKids), Toronto, Ontario, Canada
| | - Maggie Chapman
- IWK Health Centre Medical Genetics, Halifax, Nova Scotia, Canada
| | | | - Jean Paul Collet
- University of British Columbia, Vancouver, British Columbia, Canada
| | - Amy Pender
- McMaster Children's hospital, Hamilton, Ontario, Canada
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Tanaka NYY, Turcato MF, Nicoletti CF, Nonino CB, Martins LD, Iannetta O, Guerreiro CT, Santos GG, Marchini JS. Effects of Short-Term Calcium Supplementation in Children and Adolescents with Phenylketonuria. J Clin Densitom 2018; 21:48-53. [PMID: 28302355 DOI: 10.1016/j.jocd.2017.02.001] [Citation(s) in RCA: 4] [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: 09/15/2016] [Revised: 02/03/2017] [Accepted: 02/13/2017] [Indexed: 10/20/2022]
Abstract
Reduction of bone mineral density and the risk of osteopenia have been reported to occur in phenylketonuria (PKU) patients. This study aimed to evaluate the short-term effects of calcium supplementation in phenylketonuric children and adolescents. The study included 18 patients with PKU aged 5-18 yr (61% male) under clinical and nutritional treatment. Evaluation of food intake, anthropometry, and biochemical and phalangeal quantitative ultrasound were performed before (phase 1) and after (phase 2) calcium supplementation (1000 mg/d) for 34 d. Statistical analysis was performed using t test for paired samples, Wilcoxon's test, and McNemar's test (p <0.05). There was an inadequate intake of phosphorus and vitamin D, the same occurring with serum concentrations of these nutrients. About 50% of the patients had an accumulation of adipose tissue measures, with a negative correlation between Z-score, body mass index, and phalangeal quantitative ultrasound (amplitude-dependent speed of sound [AD-SoS]). There was a significant difference in urinary phosphorus excretion with higher values before supplementation. Comparison of the two phases revealed significantly higher AD-SoS values after the supplementation (p = 0.017). The reduction in phosphorus excretion associated with increased AD-SoS between the two phases suggested increased bone formation, and showed no negative effects in relation to short-term calcium supplementation in children and in adolescents with PKU.
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Affiliation(s)
- Nancy Y Y Tanaka
- Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
| | - Marlene F Turcato
- Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Carolina F Nicoletti
- Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Carla B Nonino
- Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Luciana D Martins
- Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Odilon Iannetta
- Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Carlos T Guerreiro
- Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Gisele G Santos
- Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Júlio S Marchini
- Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
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Potter BK, Hutton B, Clifford TJ, Pallone N, Smith M, Stockler S, Chakraborty P, Barbeau P, Garritty CM, Pugliese M, Rahman A, Skidmore B, Tessier L, Tingley K, Coyle D, Greenberg CR, Korngut L, MacKenzie A, Mitchell JJ, Nicholls S, Offringa M, Schulze A, Taljaard M. Establishing core outcome sets for phenylketonuria (PKU) and medium-chain Acyl-CoA dehydrogenase (MCAD) deficiency in children: study protocol for systematic reviews and Delphi surveys. Trials 2017; 18:603. [PMID: 29258568 PMCID: PMC5735866 DOI: 10.1186/s13063-017-2327-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 11/13/2017] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Inherited metabolic diseases (IMD) are a large group of rare single-gene disorders that are typically diagnosed early in life. There are important evidence gaps related to the comparative effectiveness of therapies for IMD, which are in part due to challenges in conducting randomized controlled trials (RCTs) for rare diseases. Registry-based RCTs present a unique opportunity to address these challenges provided the registries implement standardized collection of outcomes that are important to patients and their caregivers and to clinical providers and healthcare systems. Currently there is no core outcome set (COS) for studies evaluating interventions for paediatric IMD. This protocol outlines a study that will establish COS for each of two relatively common IMD in children, phenylketonuria (PKU) and medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. METHODS This two-part study is registered with the Core Outcome Measures in Effectiveness Trials (COMET) initiative. Part 1 includes a rapid review and development of an evidence map to identify a comprehensive listing of outcomes reported in past studies of PKU and MCAD deficiency. The review follows established methods for knowledge synthesis, including a comprehensive search strategy, two stages of screening citations against inclusion/exclusion criteria by two reviewers working independently, and extraction of important data elements from eligible studies, including details of the outcomes collected and outcome measurement instruments. The review findings will inform part 2 of our study, a set of Delphi surveys to establish consensus on the highest priority outcomes for each condition. Healthcare providers, families of children with PKU or MCAD deficiency, and health system decision-makers will be invited to participate in two to three rounds of Delphi surveys. The design of the surveys will involve parents of children with IMD who are part of a family advisory forum. DISCUSSION This protocol is a crucial step in developing the capacity to launch RCTs with meaningful outcomes that address comparative effectiveness questions in the field of paediatric IMD. Such trials will contribute high-quality evidence to inform decision-making by patients and their family members, clinicians, and policy-makers.
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Affiliation(s)
- Beth K. Potter
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Drive, Ottawa, ON K1G 5Z3 Canada
| | - Brian Hutton
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Drive, Ottawa, ON K1G 5Z3 Canada
- Ottawa Hospital Research Institute, Ottawa, ON Canada
| | - Tammy J. Clifford
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Drive, Ottawa, ON K1G 5Z3 Canada
- Canadian Agency for Drugs and Technologies in Health, Ottawa, ON Canada
| | - Nicole Pallone
- Patient/family partner and Canadian PKU & Allied Disorders Inc, Sparwood, BC Canada
| | - Maureen Smith
- Patient/family partner and Canadian Organization for Rare Disorders, Ottawa, ON Canada
| | - Sylvia Stockler
- BC Children’s Hospital and University of British Columbia, Vancouver, BC Canada
| | - Pranesh Chakraborty
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON Canada
| | | | | | - Michael Pugliese
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Drive, Ottawa, ON K1G 5Z3 Canada
| | - Alvi Rahman
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Drive, Ottawa, ON K1G 5Z3 Canada
| | | | - Laure Tessier
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON Canada
| | - Kylie Tingley
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Drive, Ottawa, ON K1G 5Z3 Canada
| | - Doug Coyle
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Drive, Ottawa, ON K1G 5Z3 Canada
| | | | - Lawrence Korngut
- Department of Clinical Neurosciences, University of Calgary, Calgary, AB Canada
| | - Alex MacKenzie
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON Canada
| | | | - Stuart Nicholls
- Clinical Research Unit, Children’s Hospital of Eastern Ontario, Ottawa, ON Canada
- Ontario Child Health SUPPORT Unit (OCHSU), Ottawa, ON Canada
| | - Martin Offringa
- Hospital for Sick Children and University of Toronto, Toronto, ON Canada
| | - Andreas Schulze
- Hospital for Sick Children and University of Toronto, Toronto, ON Canada
| | - Monica Taljaard
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Drive, Ottawa, ON K1G 5Z3 Canada
- Ottawa Hospital Research Institute, Ottawa, ON Canada
| | - In collaboration with the Canadian Inherited Metabolic Diseases Research Network
- School of Epidemiology and Public Health, University of Ottawa, 600 Peter Morand Drive, Ottawa, ON K1G 5Z3 Canada
- Ottawa Hospital Research Institute, Ottawa, ON Canada
- Canadian Agency for Drugs and Technologies in Health, Ottawa, ON Canada
- Patient/family partner and Canadian PKU & Allied Disorders Inc, Sparwood, BC Canada
- Patient/family partner and Canadian Organization for Rare Disorders, Ottawa, ON Canada
- BC Children’s Hospital and University of British Columbia, Vancouver, BC Canada
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON Canada
- University of Manitoba, Winnipeg, MB Canada
- Department of Clinical Neurosciences, University of Calgary, Calgary, AB Canada
- McGill University Health Centre, Montreal, QC Canada
- Clinical Research Unit, Children’s Hospital of Eastern Ontario, Ottawa, ON Canada
- Ontario Child Health SUPPORT Unit (OCHSU), Ottawa, ON Canada
- Hospital for Sick Children and University of Toronto, Toronto, ON Canada
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6
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Medford E, Hare DJ, Wittkowski A. Demographic and Psychosocial Influences on Treatment Adherence for Children and Adolescents with PKU: A Systematic Review. JIMD Rep 2017; 39:107-116. [PMID: 28840576 DOI: 10.1007/8904_2017_52] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 07/20/2017] [Accepted: 07/24/2017] [Indexed: 02/21/2023] Open
Abstract
Phenylketonuria (PKU) is a rare genetic disorder in which the amino acid phenylalanine cannot be sufficiently metabolised. Although a build-up of phenylalanine causes irreversible cognitive impairment, this can be prevented through a strict, lifelong diet restricted in natural protein. Despite the severe consequences of poor metabolic control, many children and adolescents have phenylalanine levels above their recommended limits. This systematic review was the first to examine studies reporting demographic and/or psychosocial influences on blood phenylalanine levels, with the aim to identify factors that were robustly linked with metabolic control. Four electronic databases were searched, yielding 1,808 articles. Articles were included if they reported a statistical examination of the association between one or more demographic or psychosocial factor(s) and metabolic control (as measured by blood phenylalanine concentration) for children and adolescents with PKU. Twenty-nine studies were selected for inclusion, which examined a range of child, parent and family factors related to blood phenylalanine levels. The most reproducible association was with child age, with metabolic control worsening with increasing age. This suggests that interventions promoting treatment adherence would be particularly beneficial for adolescents. There was a paucity of studies in some areas, and the quality of included studies varied; therefore, the conclusions of this review are preliminary. Research recommendations focus on promoting the growth of the evidence-base to support clinical practice.
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Affiliation(s)
- Emma Medford
- School of Health Sciences, University of Manchester, Manchester, UK.,Greater Manchester Mental Health NHS Foundation Trust, Manchester, UK
| | | | - Anja Wittkowski
- School of Health Sciences, University of Manchester, Manchester, UK. .,Greater Manchester Mental Health NHS Foundation Trust, Manchester, UK.
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7
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García MI, Araya G, Coo S, Waisbren SE, de la Parra A. Treatment adherence during childhood in individuals with phenylketonuria: Early signs of treatment discontinuation. Mol Genet Metab Rep 2017; 11:54-58. [PMID: 28491816 PMCID: PMC5412103 DOI: 10.1016/j.ymgmr.2017.04.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 04/13/2017] [Accepted: 04/13/2017] [Indexed: 10/29/2022] Open
Abstract
INTRODUCTION Phenylketonuria (PKU) is an autosomal recessive disorder characterized by a deficiency in phenylalanine (Phe) hydroxylase activity. Early diagnosis and continuous treatment with a low Phe diet prevents severe neurological and cognitive impairment. AIMS 1. Analyze how treatment adherence evolves through infancy, childhood, and early adolescence in individuals with PKU. 2. Identify early signs of treatment discontinuation. METHODOLOGY This longitudinal, retrospective study included 75 children diagnosed through newborn screening, ages 7 to 13 years. Data on blood Phe concentration, number of blood samples sent, proportion of samples with Phe concentrations over the recommended range, and number of visits to the metabolism clinic were recorded. Logistic regression analysis was used to identify the variables that predict treatment discontinuation before 13 years of age. RESULTS A progressive increase in mean blood Phe concentrations with age was identified. The greatest increase occurred between the first and second years of life. By age ten, mean Phe blood concentration of the group was above the recommended range. The proportion of samples with Phe concentrations over the recommended range also increased with age, from an average of 13% during the first year of life to 67% in early adolescence. Sixty-eight percent of the children attended the outpatient clinic and sent samples from birth to the time of the study. Individuals who discontinued follow-up showed significantly higher mean blood Phe concentrations (360 vs. 220.9 μmol/L; p = 0.004) and the proportion of samples over the recommended range (37% vs. 12% p = 0.002) was significantly higher during the second year of life. Mean age for children who discontinued treatment was 5.5 years of age. Blood Phe concentration values at 12 to 23 months of age and at 6 to 8 years of age significantly predicted treatment discontinuation before 13 years of age. CONCLUSION Treatment adherence in PKU diminishes with age. Early signs of treatment discontinuation can be identified during the second year of life, allowing preventive interventions in high risk groups.
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Affiliation(s)
- María Ignacia García
- Laboratory of Genetics and Metabolic Disease of INTA, Universidad de Chile, Chile
| | - Gabriela Araya
- Laboratory of Genetics and Metabolic Disease of INTA, Universidad de Chile, Chile
| | - Soledad Coo
- Centro de Apego y Regulación Emocional CARE, Universidad del Desarrollo, Chile
| | - Susan E Waisbren
- Division of Genetics and Genomics, Boston Children's Hospital and Harvard Medical School, United States
| | - Alicia de la Parra
- Laboratory of Genetics and Metabolic Disease of INTA, Universidad de Chile, Chile
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8
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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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9
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Abstract
PURPOSE OF REVIEW The purpose is to discuss advances in the nutritional and pharmacological management of phenylketonuria (PKU). RECENT FINDINGS Glycomacropeptide (GMP), a whey protein produced during cheese production, is a low-phenylalanine (phe) intact protein that represents a new dietary alternative to synthetic amino acids for people with PKU. Skeletal fragility is a long-term complication of PKU that based on murine research, appears to result from both genetic and nutritional factors. Skeletal fragility in murine PKU is attenuated with the GMP diet, compared with an amino acid diet, allowing greater radial bone growth. Pharmacologic therapy with tetrahydrobiopterin, acting as a molecular chaperone for phenylalanine hydroxylase, increases tolerance to dietary phe in some individuals. Large neutral amino acids inhibit phe transport across the intestinal mucosa and blood-brain barrier, and are most effective for individuals unable to comply with the low-phe diet. SUMMARY Although a low-phe synthetic amino acid diet remains the mainstay of PKU management, new nutritional and pharmacological treatment options offer alternative approaches to maintain lifelong low phe concentrations. GMP medical foods provide an alternative to amino acid formula that may improve bone health, and tetrahydrobiopterin permits some individuals with PKU to increase tolerance to dietary phe. Further research is needed to characterize the long-term efficacy of these new approaches for PKU management.
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Affiliation(s)
- Denise M. Ney
- Department of Nutritional Sciences and Waisman Center, University of Wisconsin-Madison, Milwaukee
| | - Robert D. Blank
- Department of Medicine, Division of Endocrinology, Diabetes, and Clinical Nutrition, Medical College of Wisconsin, Milwaukee
| | - Karen E. Hansen
- Department of Medicine, Division of Rheumatology, School of Medicine and Public Health, University of Wisconsin, USA
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