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Feillet F, Ficicioglu C, Lagler FB, Longo N, Muntau AC, Burlina A, Trefz FK, van Spronsen FJ, Arnoux JB, Lindstrom K, Lilienstein J, Clague GE, Rowell R, Burton BK. Efficacy and safety of sapropterin before and during pregnancy: Final analysis of the Kuvan® Adult Maternal Paediatric European Registry (KAMPER) maternal and Phenylketonuria Developmental Outcomes and Safety (PKUDOS) PKU-MOMs sub-registries. J Inherit Metab Dis 2024; 47:636-650. [PMID: 38433424 DOI: 10.1002/jimd.12724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 01/24/2024] [Accepted: 02/19/2024] [Indexed: 03/05/2024]
Abstract
Infants born to mothers with phenylketonuria (PKU) may develop congenital abnormalities because of elevated phenylalanine (Phe) levels in the mother during pregnancy. Maintenance of blood Phe levels between 120 and 360 μmol/L reduces risks of birth defects. Sapropterin dihydrochloride helps maintain blood Phe control, but there is limited evidence on its risk-benefit ratio when used during pregnancy. Data from the maternal sub-registries-KAMPER (NCT01016392) and PKUDOS (NCT00778206; PKU-MOMs sub-registry)-were collected to assess the long-term safety and efficacy of sapropterin in pregnant women in a real-life setting. Pregnancy and infant outcomes, and the safety of sapropterin were assessed. Final data from 79 pregnancies in 57 women with PKU are reported. Sapropterin dose was fairly constant before and during pregnancy, with blood Phe levels maintained in the recommended target range during the majority (82%) of pregnancies. Most pregnancies were carried to term, and the majority of liveborn infants were reported as 'normal' at birth. Few adverse and serious adverse events were considered related to sapropterin, with these occurring in participants with high blood Phe levels. This report represents the largest population of pregnant women with PKU exposed to sapropterin. Results demonstrate that exposure to sapropterin during pregnancy was well-tolerated and facilitated maintenance of blood Phe levels within the target range, resulting in normal delivery. This critical real-world data may facilitate physicians and patients to make informed treatment decisions about using sapropterin in pregnant women with PKU and in women of childbearing age with PKU who are responsive to sapropterin.
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Affiliation(s)
- François Feillet
- Hôpital d'enfants Brabois, INSERM 1256 NGERE, Faculty of Medicine, Vandoeuvre les Nancy, France
| | - Can Ficicioglu
- Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Florian B Lagler
- Institute of Inherited Metabolic Diseases and Department of Pediatrics, Paracelsus Medical Private University, Salzburg, Austria
| | | | - Ania C Muntau
- University Children's Hospital, Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Friedrich K Trefz
- Division of Inborn Metabolic Diseases, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Francjan J van Spronsen
- Division of Metabolic Diseases, Beatrix Children's Hospital, University Medical Center of Groningen, University of Groningen, Groningen, The Netherlands
| | | | | | | | | | | | - Barbara K Burton
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
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Carling RS, Barclay Z, Cantley N, Emmett EC, Hogg SL, Finezilber Y, Schulenburg‐Brand D, Murphy E, Moat SJ. Investigation of the relationship between phenylalanine in venous plasma and capillary blood using volumetric blood collection devices. JIMD Rep 2023; 64:468-476. [PMID: 37927487 PMCID: PMC10623100 DOI: 10.1002/jmd2.12398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/27/2023] [Accepted: 10/02/2023] [Indexed: 11/07/2023] Open
Abstract
Measurement of plasma and dried blood spot (DBS) phenylalanine (Phe) is key to monitoring patients with phenylketonuria (PKU). The relationship between plasma and capillary DBS Phe concentrations has been investigated previously, however, differences in methodology, calibration approach and assumptions about the volume of blood in a DBS sub-punch has complicated this. Volumetric blood collection devices (VBCDs) provide an opportunity to re-evaluate this relationship. Paired venous and capillary samples were collected from patients with PKU (n = 51). Capillary blood was collected onto both conventional newborn screening (NBS) cards and VBCDs. Specimens were analysed by liquid-chromatography tandem mass-spectrometry (LC-MS/MS) using a common calibrator. Use of VBCDs was evaluated qualitatively by patients. Mean bias between plasma and volumetrically collected capillary DBS Phe was -13%. Mean recovery (SD) of Phe from DBS was 89.4% (4.6). VBCDs confirmed that the volume of blood typically assumed to be present in a 3.2 mm sub-punch is over-estimated by 9.7%. Determination of the relationship between plasma and capillary DBS Phe, using a single analytical method, common calibration and VBCDs, demonstrated that once the under-recovery of Phe from DBS has been taken into account, there is no significant difference in the concentration of Phe in plasma and capillary blood. Conversely, comparison of plasma Phe with capillary DBS Phe collected on a NBS card highlighted the limitations of this approach. Introducing VBCDs for the routine monitoring of patients with PKU would provide a simple, acceptable specimen collection technique that ensures consistent sample quality and produces accurate and precise blood Phe results which are interchangeable with plasma Phe.
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Affiliation(s)
- Rachel S. Carling
- GKT School Medical EducationKings College LondonLondonUK
- Biochemical Sciences, Synnovis, Guys & St Thomas' NHSFTLondonUK
| | - Zoe Barclay
- Biochemical Sciences, Synnovis, Guys & St Thomas' NHSFTLondonUK
| | - Nathan Cantley
- Department of Clinical Biochemistry, Severn PathologySouthmead Hospital, North Bristol NHS TrustBristolUK
| | - Erin C. Emmett
- Biochemical Sciences, Synnovis, Guys & St Thomas' NHSFTLondonUK
| | - Sarah L. Hogg
- Biochemical Genetics UnitCambridge University HospitalsCambridgeUK
| | - Yael Finezilber
- Charles Dent Metabolic UnitNational Hospital for Neurology and Neurosurgery, Queen SquareLondonUK
| | - Danja Schulenburg‐Brand
- Department of Haematology, Immunology and Metabolic MedicineUniversity Hospital WalesCardiffUK
| | - Elaine Murphy
- Charles Dent Metabolic UnitNational Hospital for Neurology and Neurosurgery, Queen SquareLondonUK
| | - Stuart J. Moat
- Department of Medical Biochemistry, Immunology & ToxicologyUniversity Hospital WalesCardiffUK
- School of MedicineCardiff University, University Hospital WalesCardiffUK
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Gao L, Smith N, Kaushik D, Milner S, Kong R. Validation and application of volumetric absorptive microsampling (VAMS) dried blood method for phenylalanine measurement in patients with phenylketonuria. Clin Biochem 2023; 116:65-74. [PMID: 37001750 DOI: 10.1016/j.clinbiochem.2023.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 03/26/2023] [Accepted: 03/28/2023] [Indexed: 03/31/2023]
Abstract
BACKGROUND Frequent blood phenylalanine (Phe) measurement is required for phenylketonuria (PKU) patients for diagnosis and disease status monitoring. Though various methods are available for blood Phe measurement, there is a lack of validated quantitative methods for measuring Phe with less than 15% variability. A method to allow at home blood sample collection for the PKU community is in high demand. METHODS A volumetric absorptive microsampling (VAMS) dried blood collection high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and fully validated for blood Phe measurement in compliance with regulatory guidances. The method accuracy, precision, stability, selectivity, matrix and hematocrit effects were assessed. A venous plasma collection HPLC-MS/MS method was developed and validated as a reference method. 311 matching VAMS and plasma samples were collected from 24 PKU subjects in a Phase 2 clinical study. Phe measurements using the two methods were compared. RESULTS Both VAMS and the plasma sample collection methods met the acceptance criteria for Good Laboratory Practice (GLP) bioanalytical analysis. Comparisons showed a high Pearson's correlation of 0.9813. The Passing-Bablok analysis showed that the difference was estimated to be less than 5% and Bland Altman analysis indicated that the difference was proportional with Phe concentration and for the majority of samples (88.85%) the measurement was within ±20% difference. Following 7 days treatment with 60 or 20 mg/kg/day PTC923 (Sepiapterin) or 20 mg/kg/day sapropterin, PKU patients exhibited respectively -206.4, -146.9, and -91.5 µmol/L reductions of blood Phe as measured by the VAMS method. CONCLUSIONS Concordant results were obtained using VAMS and plasma methods, which demonstrated that VAMS is a reliable method for clinical applications to monitor blood Phe for PKU patients.
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Perko D, Groselj U, Cuk V, Iztok Remec Z, Zerjav Tansek M, Drole Torkar A, Krhin B, Bicek A, Oblak A, Battelino T, Repic Lampret B. Comparison of Tandem Mass Spectrometry and the Fluorometric Method-Parallel Phenylalanine Measurement on a Large Fresh Sample Series and Implications for Newborn Screening for Phenylketonuria. Int J Mol Sci 2023; 24:ijms24032487. [PMID: 36768810 PMCID: PMC9916910 DOI: 10.3390/ijms24032487] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 01/25/2023] [Accepted: 01/26/2023] [Indexed: 02/01/2023] Open
Abstract
Phenylketonuria (PKU) was the first disease to be identified by the newborn screening (NBS) program. Currently, there are various methods for determining phenylalanine (Phe) values, with tandem mass spectrometry (MS/MS) being the most widely used method worldwide. We aimed to compare the MS/MS method with the fluorometric method (FM) for measuring Phe in the dried blood spot (DBS) and the efficacy of both methods in the NBS program. The FM was performed using a neonatal phenylalanine kit and a VICTOR2TM D fluorometer. The MS/MS method was performed using a NeoBaseTM 2 kit and a Waters Xevo TQD mass spectrometer. The Phe values measured with the MS/MS method were compared to those determined by the FM. The cut-off value for the NBS program was set at 120 µmol/L for FM and 85 µmol/L for MS/MS. We analyzed 54,934 DBS. The measured Phe values varied from 12 to 664 µmol/L, with a median of 46 µmol/L for the MS/MS method and from 10 to 710 µmol/L, with a median of 70 µmol/L for the FM. The Bland-Altman analysis indicated a bias of -38.9% (-23.61 µmol/L) with an SD of 21.3% (13.89 µmol/L) when comparing the MS/MS method to the FM. The Phe value exceeded the cut-off in 187 samples measured with FM and 112 samples measured with MS/MS. The FM had 181 false positives, while the MS/MS method had 106 false positives. Our study showed that the MS/MS method gives lower results compared to the FM. Despite that, none of the true positives would be missed, and the number of false-positive results would be significantly lower compared to the FM.
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Affiliation(s)
- Dasa Perko
- Clinical Institute for Special Laboratory Diagnostics, University Children’s Hospital, UMC Ljubljana, 1000 Ljubljana, Slovenia
- Correspondence:
| | - Urh Groselj
- Department of Endocrinology, Diabetes and Metabolic Diseases, University Children’s Hospital, UMC Ljubljana, 1000 Ljubljana, Slovenia
| | - Vanja Cuk
- Clinical Institute for Special Laboratory Diagnostics, University Children’s Hospital, UMC Ljubljana, 1000 Ljubljana, Slovenia
| | - Ziga Iztok Remec
- Clinical Institute for Special Laboratory Diagnostics, University Children’s Hospital, UMC Ljubljana, 1000 Ljubljana, Slovenia
| | - Mojca Zerjav Tansek
- Department of Endocrinology, Diabetes and Metabolic Diseases, University Children’s Hospital, UMC Ljubljana, 1000 Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Ana Drole Torkar
- Department of Endocrinology, Diabetes and Metabolic Diseases, University Children’s Hospital, UMC Ljubljana, 1000 Ljubljana, Slovenia
| | - Blaz Krhin
- Department of Nuclear Medicine, UMC Ljubljana, 1000 Ljubljana, Slovenia
| | - Ajda Bicek
- Department of Nuclear Medicine, UMC Ljubljana, 1000 Ljubljana, Slovenia
| | - Adrijana Oblak
- Department of Nuclear Medicine, UMC Ljubljana, 1000 Ljubljana, Slovenia
| | - Tadej Battelino
- Department of Endocrinology, Diabetes and Metabolic Diseases, University Children’s Hospital, UMC Ljubljana, 1000 Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Barbka Repic Lampret
- Clinical Institute for Special Laboratory Diagnostics, University Children’s Hospital, UMC Ljubljana, 1000 Ljubljana, Slovenia
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Al-Bari AA. Current Scenario and Future Direction of Newborn Screening and Management Program for Phenylketonuria in Bangladesh. JOURNAL OF INBORN ERRORS OF METABOLISM AND SCREENING 2022. [DOI: 10.1590/2326-4594-jiems-2021-0024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Yazdanpanah M, Yuan L. A highly accurate mass spectrometry method for the quantification of phenylalanine and tyrosine on dried blood spots: Combination of liquid chromatography, phenylalanine/tyrosine-free blood calibrators and multi-point/dynamic calibration. Clin Biochem 2021; 101:35-41. [PMID: 34896097 DOI: 10.1016/j.clinbiochem.2021.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/03/2021] [Accepted: 12/04/2021] [Indexed: 11/18/2022]
Abstract
BACKGROUND Measurement of quantitative levels of phenylalanine and tyrosine in blood is an essential test for the diagnosis of and monitoring genetic disorders associated with phenylalanine metabolism, such as phenylketonuria (PKU), tyrosinemia, and defects of tetrahydrobiopterin synthesis and recycling. We developed a highly accurate and fast liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for the quantification of phenylalanine and tyrosine on dried blood spot (DBS). We also designed a performance score system to evaluate various calibration methods in matrix matched material. METHODS Phenylalanine/tyrosine-free whole blood was used to make accurate and stable DBS calibrators. Six calibrators cover the range of 0-1000 µmol/L. Underivatized phenylalanine and tyrosine were extracted and measured by LC-MS/MS. Precision, accuracy, limit of quantification, recovery and carryover were validated. External quality assurance materials were also used to evaluate performance of multi-point calibrations and single-point calibrations. RESULTS The run time was 4.5-minute. Accuracy analysis showed good agreement with reference materials. Precision, recovery, and the lower and upper limit of quantification met the criteria. When phenylalanine and tyrosine concentrations were less than 150 µmol/L, the 5-point calibration without the calibrator of 1000 µmol/L had the best performance. When the concentrations were > 250 µmol/L, the single-point calibration of 500 µmol/L had the best performance. CONCLUSION We developed a simple, fast and highly accurate method for the detection of phenylalanine and tyrosine on DBS, with chromatographic separation and underivatized analysis. Based on the calibration performance, a 6-point calibration method is satisfying for this test. An optional dynamic calibration method, which includes 6-point calibration, 5-point calibration and single-point calibration, can further increase test reliability.
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Affiliation(s)
- Mehrdad Yazdanpanah
- Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Libin Yuan
- Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
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Differences of Phenylalanine Concentrations in Dried Blood Spots and in Plasma: Erythrocytes as a Neglected Component for This Observation. Metabolites 2021; 11:metabo11100680. [PMID: 34677395 PMCID: PMC8537883 DOI: 10.3390/metabo11100680] [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: 09/13/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 11/17/2022] Open
Abstract
Monitoring phenylalanine (Phe) concentrations is critical for the management of phenylketonuria (PKU). This can be done in dried blood spots (DBS) or in EDTA plasma derived from capillary or venous blood. Different techniques are used to measure Phe, the most common being flow-injection analysis tandem mass spectrometry (FIA-MS-MS) and ion exchange chromatography (IEC). Significant differences have been reported between Phe concentrations in various sample types measured by different techniques, the cause of which is not yet understood. We measured Phe concentrations in 240 venous blood samples from 199 patients with hyperphenylalaninemia in dried blood spots, EDTA plasma and erythrocytes by FIA-MS-MS and IEC. Phe concentrations were significantly lower in erythrocytes than in plasma leading to about 19% lower Phe DBS concentrations compared with plasma independent from the method used for quantification. As most therapy recommendations for PKU patients are based on plasma concentrations reliable conversion of DBS into plasma concentrations is necessary. Variances of Phe concentrations in plasma and DBS are not linear but increases with higher concentrations indicating heteroscedasticity. We therefore suggest the slope of the 75th percentile from quantile regression as a correction factor.
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Urine Phenylacetylglutamine Determination in Patients with Hyperphenylalaninemia. J Clin Med 2021; 10:jcm10163674. [PMID: 34441968 PMCID: PMC8396897 DOI: 10.3390/jcm10163674] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/10/2021] [Accepted: 08/16/2021] [Indexed: 12/11/2022] Open
Abstract
Phenylketonuria (PKU), an autosomal-recessive inborn error of phenylalanine (Phe) metabolism is the most prevalent disorder of amino acid metabolism. Currently, clinical follow-up relies on frequent monitoring of Phe levels in blood. We hypothesize that the urine level of phenylacetylglutamine (PAG), a phenyl-group marker, could be used as a non-invasive biomarker. In this cross-sectional study, a validated liquid chromatography coupled to tandem mass spectrometry (LC-MS) method was used for urinary PAG quantification in 35 participants with hyperphenylalaninemia (HPA) and 33 age- and sex-matched healthy controls. We have found that (a) PKU patients present higher urine PAG levels than healthy control subjects, and that (b) there is a significant correlation between urine PAG and circulating Phe levels in patients with HPA. In addition, we show a significant strong correlation between Phe levels from venous blood samples and from capillary finger-prick dried blood spot (DBS) samples collected at the same time in patients with HPA. Further research in order to assess the potential role of urine PAG as a non-invasive biomarker in PKU is warranted.
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Abstract
Phenylketonuria (PKU; also known as phenylalanine hydroxylase (PAH) deficiency) is an autosomal recessive disorder of phenylalanine metabolism, in which especially high phenylalanine concentrations cause brain dysfunction. If untreated, this brain dysfunction results in severe intellectual disability, epilepsy and behavioural problems. The prevalence varies worldwide, with an average of about 1:10,000 newborns. Early diagnosis is based on newborn screening, and if treatment is started early and continued, intelligence is within normal limits with, on average, some suboptimal neurocognitive function. Dietary restriction of phenylalanine has been the mainstay of treatment for over 60 years and has been highly successful, although outcomes are still suboptimal and patients can find the treatment difficult to adhere to. Pharmacological treatments are available, such as tetrahydrobiopterin, which is effective in only a minority of patients (usually those with milder PKU), and pegylated phenylalanine ammonia lyase, which requires daily subcutaneous injections and causes adverse immune responses. Given the drawbacks of these approaches, other treatments are in development, such as mRNA and gene therapy. Even though PAH deficiency is the most common defect of amino acid metabolism in humans, brain dysfunction in individuals with PKU is still not well understood and further research is needed to facilitate development of pathophysiology-driven treatments.
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Affiliation(s)
- Francjan J van Spronsen
- Beatrix Children's Hospital, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands.
| | - Nenad Blau
- University Children's Hospital in Zurich, Zurich, Switzerland
| | - Cary Harding
- Department of Molecular and Medical Genetics and Department of Pediatrics, Oregon Health & Science University, Oregon, USA
| | | | - Nicola Longo
- Department of Pediatrics, University of Utah, Salt Lake City, Utah, USA
| | - Annet M Bosch
- University of Amsterdam, Department of Pediatrics, Division of Metabolic Disorders, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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Coene KLM, Timmer C, Goorden SMI, ten Hoedt AE, Kluijtmans LAJ, Janssen MCH, Rennings AJM, Prinsen HCMT, Wamelink MMC, Ruijter GJG, Körver‐Keularts IMLW, Heiner‐Fokkema MR, van Spronsen FJ, Hollak CE, Vaz FM, Bosch AM, Huigen MCDG. Monitoring phenylalanine concentrations in the follow-up of phenylketonuria patients: An inventory of pre-analytical and analytical variation. JIMD Rep 2021; 58:70-79. [PMID: 33728249 PMCID: PMC7932865 DOI: 10.1002/jmd2.12186] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 09/17/2020] [Accepted: 11/05/2020] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Reliable measurement of phenylalanine (Phe) is a prerequisite for adequate follow-up of phenylketonuria (PKU) patients. However, previous studies have raised concerns on the intercomparability of plasma and dried blood spot (DBS) Phe results. In this study, we made an inventory of differences in (pre-)analytical methodology used for Phe determination across Dutch laboratories, and compared DBS and plasma results. METHODS Through an online questionnaire, we assessed (pre-)analytical Phe measurement procedures of seven Dutch metabolic laboratories. To investigate the difference between plasma and DBS Phe, participating laboratories received simultaneously collected plasma-DBS sets from 23 PKU patients. In parallel, 40 sample sets of DBS spotted from either venous blood or capillary fingerprick were analyzed. RESULTS Our data show that there is no consistency on standard operating procedures for Phe measurement. The association of DBS to plasma Phe concentration exhibits substantial inter-laboratory variation, ranging from a mean difference of -15.5% to +30.6% between plasma and DBS Phe concentrations. In addition, we found a mean difference of +5.8% in Phe concentration between capillary DBS and DBS prepared from venous blood. CONCLUSIONS The results of our study point to substantial (pre-)analytical variation in Phe measurements, implicating that bloodspot Phe results should be interpreted with caution, especially when no correction factor is applied. To minimize variation, we advocate pre-analytical standardization and analytical harmonization of Phe measurements, including consensus on application of a correction factor to adjust DBS Phe to plasma concentrations.
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Affiliation(s)
- Karlien L. M. Coene
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CentreNijmegenThe Netherlands
| | - Corrie Timmer
- Department Endocrinology and MetabolismAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
| | - Susan M. I. Goorden
- Laboratory Genetic Metabolic Diseases, Department of Clinical ChemistryAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
| | - Amber E. ten Hoedt
- Department of Paediatrics, Division of Metabolic DisordersAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
| | - Leo A. J. Kluijtmans
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CentreNijmegenThe Netherlands
| | - Mirian C. H. Janssen
- Department of Internal MedicineRadboud University Medical CentreNijmegenThe Netherlands
| | | | | | - Mirjam M. C. Wamelink
- Metabolic Laboratory, Department of Clinical ChemistryAmsterdam UMC, Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - George J. G. Ruijter
- Center for Lysosomal and Metabolic Diseases, Department of Clinical GeneticsErasmus MCRotterdamThe Netherlands
| | - Irene M. L. W. Körver‐Keularts
- Laboratory of Biochemical Genetics, Department of Clinical GeneticsMaastricht University Medical CentreMaastrichtThe Netherlands
| | - M. Rebecca Heiner‐Fokkema
- Laboratory of Metabolic DiseasesUniversity of Groningen, University Medical Center GroningenGroningenThe Netherlands
| | - Francjan J. van Spronsen
- Division of Metabolic DiseasesBeatrix Children's Hospital, University Medical Centre GroningenGroningenThe Netherlands
| | - Carla E. Hollak
- Department Endocrinology and MetabolismAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
| | - Frédéric M. Vaz
- Laboratory Genetic Metabolic Diseases, Department of Clinical ChemistryAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
| | - Annet M. Bosch
- Department of Paediatrics, Division of Metabolic DisordersAmsterdam UMC, University of AmsterdamAmsterdamThe Netherlands
| | - Marleen C. D. G. Huigen
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CentreNijmegenThe Netherlands
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Olson JE, Braegelman AS, Zou L, Webber MJ, Camden JP. Capture of Phenylalanine and Phenylalanine-Terminated Peptides Using a Supramolecular Macrocycle for Surface-Enhanced Raman Scattering Detection. APPLIED SPECTROSCOPY 2020; 74:1374-1383. [PMID: 32508116 DOI: 10.1177/0003702820937333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The cucurbit[n]uril (CB[n]) family of macrocycles are known to bind a variety of small molecules with high affinity. These motifs thus have promise in an ever-growing list of trace detection methods. Surface-enhanced Raman scattering (SERS) detection schemes employing CB[n] motifs exhibit increased sensitivity due to selective concentration of the analyte at the nanoparticle surface, coupled with the ability of CB[n] to facilitate the formation of well-defined electromagnetic hot spots. Herein, we report a CB[7] SERS assay for quantification of phenylalanine (Phe) and further demonstrate its utility for detecting peptides with an N-terminal Phe. The CB[7]-guest interaction improves the sensitivity 5-25-fold over direct detection of Phe using citrate-capped silver nanoparticle aggregates, enabling use of a portable Raman system. We further illustrate detection of insulin via binding of CB[7] to the N-terminal Phe residue on its B-chain, suggesting a general strategy for detecting Phe-terminated peptides of clinically relevant biomolecules.
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Affiliation(s)
- Jacob E Olson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, USA
| | - Adam S Braegelman
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, USA
| | - Lei Zou
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, USA
| | - Matthew J Webber
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, USA
| | - Jon P Camden
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, USA
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van Vliet K, van Ginkel WG, van Dam E, de Blaauw P, Koehorst M, Kingma HA, van Spronsen FJ, Heiner-Fokkema MR. Dried blood spot versus venous blood sampling for phenylalanine and tyrosine. Orphanet J Rare Dis 2020; 15:82. [PMID: 32245393 PMCID: PMC7118958 DOI: 10.1186/s13023-020-1343-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 02/25/2020] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND This study investigated the agreement between various dried blood spot (DBS) and venous blood sample measurements of phenylalanine and tyrosine concentrations in Phenylketonuria (PKU) and Tyrosinemia type 1 (TT1) patients. STUDY DESIGN Phenylalanine and tyrosine concentrations were studied in 45 PKU/TT1 patients in plasma from venous blood in lithium heparin (LH) and EDTA tubes; venous blood from LH and EDTA tubes on a DBS card; venous blood directly on a DBS card; and capillary blood on a DBS card. Plasma was analyzed with an amino acid analyzer and DBS were analyzed with liquid chromatography-mass spectrometry. Agreement between different methods was assessed using Passing and Bablok fit and Bland Altman analyses. RESULTS In general, phenylalanine concentrations in LH plasma were comparable to capillary DBS, whereas tyrosine concentrations were slightly higher in LH plasma (constant bias of 6.4 μmol/L). However, in the low phenylalanine range, most samples had higher phenylalanine concentrations in DBS compared to LH plasma. Remarkably, phenylalanine and tyrosine in EDTA plasma were higher compared to all other samples (slopes ranging from 7 to 12%). No differences were observed when comparing capillary DBS to other DBS. CONCLUSIONS Overall agreement between plasma and DBS is good. However, bias is specimen- (LH vs EDTA), and possibly concentration- (low phenylalanine) dependent. Because of the overall good agreement, we recommend the use of a DBS-plasma correction factor for DBS measurement. Each laboratory should determine their own factor dependent on filter card type, extraction and calibration protocols taking the LH plasma values as gold standard.
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Affiliation(s)
- Kimber van Vliet
- Division of Metabolic Diseases, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Wiggert G van Ginkel
- Division of Metabolic Diseases, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Esther van Dam
- Division of Metabolic Diseases, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Pim de Blaauw
- Department of Laboratory Medicine, Laboratory of Metabolic Diseases, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, P.O. Box 30.001, 9700 RB, The Netherlands
| | - Martijn Koehorst
- Department of Laboratory Medicine, Laboratory of Metabolic Diseases, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, P.O. Box 30.001, 9700 RB, The Netherlands
| | - Hermi A Kingma
- Department of Laboratory Medicine, Laboratory of Metabolic Diseases, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, P.O. Box 30.001, 9700 RB, The Netherlands
| | - Francjan J van Spronsen
- Division of Metabolic Diseases, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - M Rebecca Heiner-Fokkema
- Department of Laboratory Medicine, Laboratory of Metabolic Diseases, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, P.O. Box 30.001, 9700 RB, The Netherlands.
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13
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Moat SJ, Schulenburg-Brand D, Lemonde H, Bonham JR, Weykamp CW, Mei JV, Shortland GS, Carling RS. Performance of laboratory tests used to measure blood phenylalanine for the monitoring of patients with phenylketonuria. J Inherit Metab Dis 2020; 43:179-188. [PMID: 31433494 PMCID: PMC7957320 DOI: 10.1002/jimd.12163] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/16/2019] [Accepted: 08/19/2019] [Indexed: 01/16/2023]
Abstract
Analysis of blood phenylalanine is central to the monitoring of patients with phenylketonuria (PKU) and age-related phenylalanine target treatment-ranges (0-12 years; 120-360 μmol/L, and >12 years; 120-600 μmol/L) are recommended in order to prevent adverse neurological outcomes. These target treatment-ranges are based upon plasma phenylalanine concentrations. However, patients are routinely monitored using dried bloodspot (DBS) specimens due to the convenience of collection. Significant differences exist between phenylalanine concentrations in plasma and DBS, with phenylalanine concentrations in DBS specimens analyzed by flow-injection analysis tandem mass spectrometry reported to be 18% to 28% lower than paired plasma concentrations analyzed using ion-exchange chromatography. DBS specimens with phenylalanine concentrations of 360 and 600 μmol/L, at the critical upper-target treatment-range thresholds would be plasma equivalents of 461 and 768 μmol/L, respectively, when a reported difference of 28% is taken into account. Furthermore, analytical test imprecision and bias in conjunction with pre-analytical factors such as volume and quality of blood applied to filter paper collection devices to produce DBS specimens affect the final test results. Reporting of inaccurate patient results when comparing DBS results to target treatment-ranges based on plasma concentrations, together with inter-laboratory imprecision could have a significant impact on patient management resulting in inappropriate dietary change and potentially adverse patient outcomes. This review is intended to provide perspective on the issues related to the measurement of phenylalanine in blood specimens and to provide direction for the future needs of PKU patients to ensure reliable monitoring of metabolic control using the target treatment-ranges.
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Affiliation(s)
- Stuart J. Moat
- Department of Medical Biochemistry, Immunology & Toxicology, University Hospital Wales, Cardiff, UK
- School of Medicine, Cardiff University, University Hospital Wales, Cardiff, UK
| | - Danja Schulenburg-Brand
- Department of Medical Biochemistry, Immunology & Toxicology, University Hospital Wales, Cardiff, UK
| | - Hugh Lemonde
- Paediatric Metabolic Medicine, Evelina Children’s Hospital, Guys & St Thomas’ NHSFT, London, UK
| | - James R. Bonham
- Department of Clinical Chemistry, Sheffield Children’s (NHS) FT, Sheffield, UK
| | - Cas W. Weykamp
- MCA Laboratory, Queen Beatrix Hospital, Winterswijk, The Netherlands
| | - Joanne V. Mei
- Newborn Screening and Molecular Biology Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | | | - Rachel S. Carling
- Biochemical Sciences, Viapath, Guys & St Thomas’ NHSFT, London, UK
- GKT School of Medical Education, King’s College, London, UK
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14
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Phenylalanine and tyrosine measurements across gestation by tandem mass spectrometer on dried blood spot cards from normal pregnant women. Genet Med 2019; 21:1821-1826. [PMID: 30626901 PMCID: PMC6620164 DOI: 10.1038/s41436-018-0407-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 12/05/2018] [Indexed: 12/22/2022] Open
Abstract
Purpose: Maternal phenylketonuria (MPKU) requires strict control of phenylalanine (Phe) and supplemental tyrosine (Tyr). Monitoring during pregnancy using dried blood spot (DBS) cards by tandem mass spectrometry (MS/MS) is now standard practice, however there are no Phe and Tyr reference ranges for DBS MS/MS method in healthy pregnant women. Methods: DBS cards (63 −1364 days in storage) from healthy women with singleton pregnancies were analyzed by MS/MS. 390 DBS cards from 170 pregnancies (5/1–39/6 weeks’ gestation), were tested. Results: Both Phe and Tyr levels declined from the first trimester (Phe: 36.2 +/− 10.6; Tyr 25.7 +/−9.7 micromol/L) to the second trimester (Phe 33.4 +/− 9.3; Tyr 21.7 +/− 6.7 micromol/L) and remained stable in the third trimester (Phe 32.3 +/− 8.7; Tyr 21.0 +/− 6.6 micromol/L). Phe and Tyr levels declined over time since collection (Phe: 0.004 micromol/L per day; Tyr 0.002 micromol/L). Nomograms by gestational age were created using raw data and data adjusted for time from sample collection. Reference ranges by trimester are provided. Conclusion: Both Phe and Tyr decline quickly during the first trimester and remain relatively constant over the second and third trimesters. These nomograms will provide a valuable resource for care of MPKU.
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15
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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: 438] [Impact Index Per Article: 62.6] [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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16
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van Spronsen FJ, van Wegberg AM, 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, Trefz FK, van Rijn M, Walter JH, MacDonald A. Key European guidelines for the diagnosis and management of patients with phenylketonuria. Lancet Diabetes Endocrinol 2017; 5:743-756. [PMID: 28082082 DOI: 10.1016/s2213-8587(16)30320-5] [Citation(s) in RCA: 249] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 09/11/2016] [Accepted: 09/28/2016] [Indexed: 12/14/2022]
Abstract
We developed European guidelines to optimise phenylketonuria (PKU) care. To develop the guidelines, we did a literature search, critical appraisal, and evidence grading according to the Scottish Intercollegiate Guidelines Network method. We used the Delphi method when little or no evidence was available. From the 70 recommendations formulated, in this Review we describe ten that we deem as having the highest priority. Diet is the cornerstone of treatment, although some patients can benefit from tetrahydrobiopterin (BH4). Untreated blood phenylalanine concentrations determine management of people with PKU. No intervention is required if the blood phenylalanine concentration is less than 360 μmol/L. Treatment is recommended up to the age of 12 years if the phenylalanine blood concentration is between 360 μmol/L and 600 μmol/L, and lifelong treatment is recommended if the concentration is more than 600 μmol/L. For women trying to conceive and during pregnancy (maternal PKU), untreated phenylalanine blood concentrations of more than 360 μmol/L need to be reduced. Treatment target concentrations are as follows: 120-360 μmol/L for individuals aged 0-12 years and for maternal PKU, and 120-600 μmol/L for non-pregnant individuals older than 12 years. Minimum requirements for the management and follow-up of patients with PKU are scheduled according to age, adherence to treatment, and clinical status. Nutritional, clinical, and biochemical follow-up is necessary for all patients, regardless of therapy.
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Affiliation(s)
- Francjan J van Spronsen
- Division of Metabolic Diseases, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.
| | - Annemiek Mj van Wegberg
- Division of Metabolic Diseases, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Kirsten Ahring
- Department of PKU, Kennedy Centre, Copenhagen University Hospital, Glostrup, Denmark
| | | | - Nenad Blau
- University Children's Hospital, Dietmar-Hoppe Metabolic Centre, Heidelberg, Germany; University Children's Hospital Zurich, Zurich, Switzerland
| | - Annet M Bosch
- Department of Paediatrics, Division of Metabolic Disorders, Academic Medical Centre, University Hospital of Amsterdam, Amsterdam, Netherlands
| | - Alberto Burlina
- Division of Inherited Metabolic Diseases, Department of Paediatrics, University Hospital of Padova, Padova, Italy
| | - Jaime Campistol
- Neuropaediatrics Department, Hospital Sant Joan de Déu, University of Barcelona, Barcelona, Spain
| | - Francois Feillet
- Department of Pediatrics, Hôpital d'Enfants Brabois, CHU Nancy, Vandoeuvre les Nancy, France
| | - Maria Giżewska
- Department of Pediatrics, Endocrinology, Diabetology, Metabolic Diseases and Cardiology of the Developmental Age, Pomeranian Medical University, Szczecin, Poland
| | - Stephan C Huijbregts
- Department of Clinical Child and Adolescent Studies-Neurodevelopmental Disorders, Faculty of Social Sciences, Leiden University, Leiden, Netherlands
| | - Shauna Kearney
- Clinical Psychology Department, Birmingham Children's Hospital, Birmingham, UK
| | - Vincenzo Leuzzi
- Department of Pediatrics, Child Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy
| | - Francois Maillot
- Internal Medicine Service, CHRU de Tours, François Rabelais University, Tours, France
| | - Ania C Muntau
- University Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fritz K Trefz
- University Children's Hospital, Dietmar-Hoppe Metabolic Centre, Heidelberg, Germany
| | - Margreet van Rijn
- Department of Dietetics, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - John H Walter
- Manchester Academic Health Sciences Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK
| | - Anita MacDonald
- Dietetic Department, Birmingham Children's Hospital, Birmingham, UK
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17
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Jani R, Coakley K, Douglas T, Singh R. Protein intake and physical activity are associated with body composition in individuals with phenylalanine hydroxylase deficiency. Mol Genet Metab 2017; 121:104-110. [PMID: 28465125 DOI: 10.1016/j.ymgme.2017.04.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 04/25/2017] [Accepted: 04/26/2017] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Determine whether body composition as it relates to dietary protein in patients with phenylalanine hydroxylase (PAH) deficiency is associated with genotype, dietary factors, and lifestyle choices. METHODS We examined associations between protein intake (intact and medical foods: MF) and body composition in PAH-deficient patients along with, physical activity, and genotype. Protein intakes (total, intact, and MF) were analysed from three-day food records with Nutrition Data System for Research (NDSR) in 59 children and 27 adults (N=86, median age=16.0years). The severity of PAH deficiency was classified using the genotype assigned value method (AV sum). Physical activity was assessed using a study-developed question (light vs. intense activity). Body composition was measured by DXA, including android:gynoid ratio (A:G), fat-free mass index (FFMI), fat mass index (FMI), and FMI:FFMI ratio. RESULTS High intact protein intake was associated with high FFMI (rs=0.75, p=0.008) and low FMI:FFMI (rs=-0.59, p=0.04) in adults. Only in children, MF protein (rs=0.38, p=0.04) was directly proportional to FFMI. Median intact protein intakes of adults (25.1 vs. 9.9g/d, p<0.001) and children (11 vs. 6g/d, p<0.001) were higher than prescribed. Only in adults, the actual median MF protein intake was lower than prescribed (53 vs. 60g/d, p=0.03). In adults and children, light activity was associated with higher fat mass indices compared to intense activity (adults: FMI:FFMI: β=1.1, p=0.001, children: FMI:FFMI: β=1.1, p=0.007; FMI β=2.1, p=0.01; A:G β=1.1, p=0.04). All associations remained significant after covariate adjustment. Genotype was not associated with body composition. CONCLUSIONS Although fat-free mass in adults was positively associated with intact protein intake, it should be consumed as prescribed per individual tolerance to maintain plasma Phe concentrations within treatment range. In children, total protein maximized with MF should be encouraged to promote lean mass. Nutrition counselling could be complemented with physical activity recommendations for optimal clinical outcomes.
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Affiliation(s)
- Rati Jani
- Department of Human Genetics, Emory University, Atlanta, GA, United States.
| | - Kathryn Coakley
- Department of Human Genetics, Emory University, Atlanta, GA, United States
| | - Teresa Douglas
- Department of Human Genetics, Emory University, Atlanta, GA, United States
| | - Rani Singh
- Department of Human Genetics, Emory University, Atlanta, GA, United States.
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18
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Mihali C, Petrescu M, Mândruţiu I, Bechet D, Nistor T, Turcuş V, Ardelean A, Benga G. COMPARISON OF PLASMA PHENYLALANINE DETERMINATION BY DENSITOMETRY OF THIN-LAYER CHROMATOGRAMS AND BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY IN RELATION WITH THE SCREENING OF PHENYLKETONURIA. ACTA ENDOCRINOLOGICA (BUCHAREST, ROMANIA : 2005) 2017; 13:203-208. [PMID: 31149174 PMCID: PMC6516440 DOI: 10.4183/aeb.2017.203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To compare two chromatographic methodologies for determination of plasma phenylalanine (Phe) and their usefulness for diagnosing hyperphenylalaninemia (HPA) and phenylketonuria (PKU). METHODS The plasma amino acids were isolated and concentrated from blood collected from infants with HPA detected by newborn screening. The plasma Phe was determined in parallel by HPLC and by image-densitometry of 2D-TLC plates. RESULTS Typical examples of 2D-TLC plates and HPLC chromatograms from infants with HPA and PKU are presented and evaluated. The Phe spot was visible on 2D - TLC plates at Phe concentrations higher than 300 µmol/L. The standard calibration curve traced after image-densitometry of the Phe spot presented high dispersion of values at each concentration of Phe, high SD values, the equation of the curve having a low R-squared value (0.862). In contrast, the standard calibration curve obtained by HPLC shows linearity on the range of concentrations from 100 - 16,000 µmol/L, extremely small SD values, the equation of the curve has a very high R-squared value (0.999). CONCLUSIONS The HPLC methodology is appropriate to confirm HPA detected by newborn or selective screening of PKU. The 2D - TLC methodology is adequate to detect patients with severe PKU.
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Affiliation(s)
- C.V. Mihali
- “Vasile Goldiş” Western University of Arad - Institute of Life Sciences, Arad, Romania
| | - M.C. Petrescu
- “Vasile Goldiş” Western University of Arad - Institute of Life Sciences, Arad, Romania
| | - I. Mândruţiu
- Cluj County Clinical Emergency Hospital - Laboratory of Genetic Explorations, Cluj-Napoca, Romania
| | - D. Bechet
- Cluj County Clinical Emergency Hospital - Laboratory of Genetic Explorations, Cluj-Napoca, Romania
| | - T.V. Nistor
- “Iuliu Haţieganu” University of Medicine and Pharmacy of Cluj-Napoca - Discipline of Biochemistry, Cluj-Napoca, Romania
| | - V. Turcuş
- “Vasile Goldiş” Western University of Arad - Institute of Life Sciences, Arad, Romania
| | - A. Ardelean
- “Vasile Goldiş” Western University of Arad - Institute of Life Sciences, Arad, Romania
| | - Gh. Benga
- “Vasile Goldiş” Western University of Arad - Institute of Life Sciences, Arad, Romania
- Cluj County Clinical Emergency Hospital - Laboratory of Genetic Explorations, Cluj-Napoca, Romania
- Romanian Academy - Cluj-Napoca Branch, Cluj-Napoca, Romania
- Academy of Medical Sciences of Romania - Cluj-Napoca Branch, Cluj-Napoca, Romania
- The Gheorghe Benga Foundation, Cluj-Napoca, Romania
- The OUTNOBEL Foundation, Cluj-Napoca, Romania
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19
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Muntau AC, Burlina A, Eyskens F, Freisinger P, De Laet C, Leuzzi V, Rutsch F, Sivri HS, Vijay S, Bal MO, Gramer G, Pazdírková R, Cleary M, Lotz-Havla AS, Munafo A, Mould DR, Moreau-Stucker F, Rogoff D. Efficacy, safety and population pharmacokinetics of sapropterin in PKU patients <4 years: results from the SPARK open-label, multicentre, randomized phase IIIb trial. Orphanet J Rare Dis 2017; 12:47. [PMID: 28274234 PMCID: PMC5343543 DOI: 10.1186/s13023-017-0600-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 02/23/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sapropterin dihydrochloride, a synthetic formulation of BH4, the cofactor for phenylalanine hydroxylase (PAH, EC 1.14.16.1), was initially approved in Europe only for patients ≥4 years with BH4-responsive phenylketonuria. The aim of the SPARK (Safety Paediatric efficAcy phaRmacokinetic with Kuvan®) trial was to assess the efficacy (improvement in daily phenylalanine tolerance, neuromotor development and growth parameters), safety and pharmacokinetics of sapropterin dihydrochloride in children <4 years. RESULTS In total, 109 male or female children <4 years with confirmed BH4-responsive phenylketonuria or mild hyperphenylalaninemia and good adherence to dietary treatment were screened. 56 patients were randomly assigned (1:1) to 10 mg/kg/day oral sapropterin plus a phenylalanine-restricted diet or to only a phenylalanine-restricted diet for 26 weeks (27 to the sapropterin and diet group and 29 to the diet-only group; intention-to-treat population). Of these, 52 patients with ≥1 pharmacokinetic sample were included in the pharmacokinetic analysis, and 54 patients were included in the safety analysis. At week 26 in the sapropterin plus diet group, mean phenylalanine tolerance was 30.5 (95% confidence interval 18.7-42.3) mg/kg/day higher than in the diet-only group (p < 0.001). The safety profile of sapropterin, measured monthly, was acceptable and consistent with that seen in studies of older children. Using non-linear mixed effect modelling, a one-compartment model with flip-flop pharmacokinetic behaviour, in which the effect of weight was substantial, best described the pharmacokinetic profile. Patients in both groups had normal neuromotor development and stable growth parameters. CONCLUSIONS The addition of sapropterin to a phenylalanine-restricted diet was well tolerated and led to a significant improvement in phenylalanine tolerance in children <4 years with BH4-responsive phenylketonuria or mild hyperphenylalaninemia. The pharmacokinetic model favours once per day dosing with adjustment for weight. Based on the SPARK trial results, sapropterin has received EU approval to treat patients <4 years with BH4-responsive phenylketonuria. TRIAL REGISTRATION ClinicalTrials.gov, NCT01376908 . Registered June 17, 2011.
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Affiliation(s)
- Ania C Muntau
- University Children's Hospital, University Medical Center Hamburg Eppendorf, Martinistrasse 52, D-20246, Hamburg, Germany.
| | | | | | | | - Corinne De Laet
- Hôpital Universitaire des Enfants Reine Fabiola, Brussels, Belgium
| | | | - Frank Rutsch
- Muenster University Children's Hospital, Muenster, Germany
| | - H Serap Sivri
- Hacettepe University School of Medicine, Ankara, Turkey
| | | | | | - Gwendolyn Gramer
- Centre for Paediatric and Adolescent Medicine, Division for Neuropaediatrics and Metabolic Medicine, University of Heidelberg, Heidelberg, Germany
| | | | | | | | - Alain Munafo
- Merck Institute for Pharmacometrics, Lausanne, Switzerland
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20
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van Dam E, Daly A, Venema-Liefaard G, van Rijn M, Derks TGJ, McKiernan PJ, Rebecca Heiner-Fokkema M, MacDonald A, van Spronsen FJ. What Is the Best Blood Sampling Time for Metabolic Control of Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients? JIMD Rep 2017; 36:49-57. [PMID: 28120161 DOI: 10.1007/8904_2016_37] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 11/26/2016] [Accepted: 12/12/2016] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Treatment of hereditary tyrosinemia type 1 with nitisinone and phenylalanine and tyrosine restricted diet has largely improved outcome, but the best blood sampling time for assessment of metabolic control is not known. AIM To study diurnal and day-to-day variation of phenylalanine and tyrosine concentrations in tyrosinemia type 1 patients. METHODS Eighteen tyrosinemia type 1 patients aged >1 year (median age 7.9 years; range 1.6-20.7) were studied. Capillary blood samples were collected 4 times a day (T1: pre-breakfast, T2: pre-midday meal, T3: before evening meal, and T4: bedtime) for 3 days. Linear mixed-effect models were used to investigate diurnal and day-to-day variation of both phenylalanine and tyrosine. RESULTS The coefficients of variation of phenylalanine and tyrosine concentrations were the lowest on T1 (13.8% and 14.1%, respectively). Tyrosine concentrations did not significantly differ between the different time points, but phenylalanine concentrations were significantly lower at T2 and T3 compared to T1 (50.1 μmol/L, 29.8 μmol/L, and 37.3 μmol/L, respectively). CONCLUSION Our results indicated that for prevention of too low phenylalanine and too high tyrosine concentrations, measurement of phenylalanine and tyrosine pre-midday meal would be best, since phenylalanine concentrations are the lowest on that time point. Our results also indicated that whilst blood tyrosine concentrations were stable over 24 h, phenylalanine fluctuated. Day-to-day variation was most stable after an overnight fast for both phenylalanine and tyrosine. Therefore, in tyrosinemia type 1 patients the most reliable time point for measuring phenylalanine and tyrosine concentrations to enable interpretation of metabolic control is pre-breakfast.
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Affiliation(s)
- Esther van Dam
- Department of Dietetics, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Groningen, The Netherlands.
| | - Anne Daly
- Birmingham Children's Hospital, Birmingham, UK
| | - Gineke Venema-Liefaard
- Department of Dietetics, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Groningen, The Netherlands
| | - Margreet van Rijn
- Department of Dietetics, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Groningen, The Netherlands
| | - Terry G J Derks
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Groningen, The Netherlands
| | | | - M Rebecca Heiner-Fokkema
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | | | - Francjan J van Spronsen
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Groningen, The Netherlands
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21
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Messina MA, Meli C, Conoci S, Petralia S. A facile method for urinary phenylalanine measurement on paper-based lab-on-chip for PKU therapy monitoring. Analyst 2017; 142:4629-4632. [DOI: 10.1039/c7an01115f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A miniaturized paper-based lab-on-chip (LoC) was developed for the facile measurement of urinary Phe (phenylalanine) level on PKU (Phenylketonuria) treated patient.
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Affiliation(s)
- M. A. Messina
- Azienda Ospedaliero Universitaria Policlinico Vittorio Emanuele
- Catania
- Italy
| | - C. Meli
- Azienda Ospedaliero Universitaria Policlinico Vittorio Emanuele
- Catania
- Italy
| | - S. Conoci
- STMicroelectronics
- Stradale Primosole
- 50-95121 Catania
- Italy
| | - S. Petralia
- STMicroelectronics
- Stradale Primosole
- 50-95121 Catania
- Italy
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22
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Abstract
Although mass spectrometry has been used clinically for decades, the advent of immunoassay technology moved the clinical laboratory to more labor saving automated platforms requiring little if any sample preparation. It became clear, however, that immunoassays lacked sufficient sensitivity and specificity necessary for measurement of certain analytes or for measurement of analytes in specific patient populations. This limitation prompted clinical laboratories to revisit mass spectrometry which could additionally be used to develop assays for which there was no commercial source. In this chapter, the clinical applications of mass spectrometry in therapeutic drug monitoring, toxicology, and steroid hormone analysis will be reviewed. Technologic advances and new clinical applications will also be discussed.
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Affiliation(s)
- D French
- University of California San Francisco, San Francisco, CA, United States.
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23
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Robinson R, Wong L, Monnat RJ, Fu E. Development of a Whole Blood Paper-Based Device for Phenylalanine Detection in the Context of PKU Therapy Monitoring. MICROMACHINES 2016; 7:mi7020028. [PMID: 30407401 PMCID: PMC6190008 DOI: 10.3390/mi7020028] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 02/04/2016] [Accepted: 02/04/2016] [Indexed: 11/30/2022]
Abstract
Laboratory-based testing does not allow for the sufficiently rapid return of data to enable optimal therapeutic monitoring of patients with metabolic diseases such as phenylketonuria (PKU). The typical turn-around time of several days for current laboratory-based testing is too slow to be practically useful for effective monitoring or optimizing therapy. This report describes the development of a rapid, paper-based, point-of-care device for phenylalanine detection using a small volume (40 μL) of whole blood. The quantitative resolution and reproducibility of this device with instrumented readout are described, together with the potential use of this device for point-of-care monitoring by PKU patients.
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Affiliation(s)
- Robert Robinson
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA.
| | - Liam Wong
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA.
| | - Raymond J Monnat
- Departments of Pathology and Genome Sciences, University of Washington, Seattle, WA 98195, USA.
| | - Elain Fu
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA.
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24
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Stroup BM, Held PK, Williams P, Clayton MK, Murali SG, Rice GM, Ney DM. Clinical relevance of the discrepancy in phenylalanine concentrations analyzed using tandem mass spectrometry compared with ion-exchange chromatography in phenylketonuria. Mol Genet Metab Rep 2016; 6:21-6. [PMID: 27014575 PMCID: PMC4789345 DOI: 10.1016/j.ymgmr.2016.01.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 01/05/2016] [Indexed: 11/05/2022] Open
Abstract
Introduction Metabolic control of phenylketonuria (PKU) and compliance with the low-phenylalanine (phe) diet are frequently assessed by measuring blood phe concentrations in dried blood spots (DBS) collected by patients instead of plasma phe concentrations. Objective Our objective was to investigate the difference in blood phe concentrations in DBS collected by subjects and analyzed using either a validated newborn screening tandem mass spectrometry (MS/MS) protocol or ion-exchange chromatography (IEC) compared to plasma phe concentrations obtained simultaneously and analyzed using IEC. Design Three to four fasting blood samples were obtained from 29 subjects with PKU, ages 15–49 years. Capillary blood was spotted on filter paper by each subject and the DBS analyzed using both MS/MS and IEC. Plasma was isolated from venous blood and analyzed using IEC. Results Blood phe concentrations in DBS analyzed using MS/MS are 28% ± 1% (n = 110, p < 0.0001) lower than plasma phe concentrations analyzed using IEC resulting in a blood phe concentration of 514 ± 23 μmol/L and a plasma phe concentration of 731 ± 32 μmol/L (mean ± SEM). This discrepancy is larger when plasma phe is > 600 μmol/L. Due to the large variability across subjects of 13.2%, a calibration factor to adjust blood phe concentrations is not recommended. Analysis of DBS using IEC reduced the discrepancy to 15 ± 2% lower phe concentrations compared to plasma analyzed using IEC (n = 38, p = 0.0001). This suggests that a major contributor to the discrepancy in phe concentrations is the analytical method. Conclusion Use of DBS analyzed using MS/MS to monitor blood phe concentrations in individuals with PKU yields significantly lower phe levels compared to plasma phe levels analyzed using IEC. Optimization of current testing methodologies for measuring phe in DBS, along with patient education regarding the appropriate technique for spotting blood on filter paper is needed to improve the accuracy of using DBS to measure phe concentrations in PKU management. Phe concentration in dried blood spots is significantly lower than plasma phe. Blood phe concentration cannot be adjusted due to large variability across subjects. Analysis of dried blood spots using IEC instead of MS/MS improves accuracy. Plasma phe concentration using IEC is the most accurate for metabolic monitoring in PKU.
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Affiliation(s)
- Bridget M Stroup
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Patrice K Held
- Wisconsin State Laboratory of Hygiene, University of Wisconsin-Madison, Madison, WI, United States
| | - Phillip Williams
- Wisconsin State Laboratory of Hygiene, University of Wisconsin-Madison, Madison, WI, United States
| | - Murray K Clayton
- Departments of Plant Pathology and Statistics, University of Wisconsin-Madison, Madison, WI, United States
| | - Sangita G Murali
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Gregory M Rice
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Denise M Ney
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, United States
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25
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Longo N, Arnold GL, Pridjian G, Enns GM, Ficicioglu C, Parker S, Cohen-Pfeffer JL. Long-term safety and efficacy of sapropterin: the PKUDOS registry experience. Mol Genet Metab 2015; 114:557-63. [PMID: 25724073 DOI: 10.1016/j.ymgme.2015.02.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/10/2015] [Accepted: 02/10/2015] [Indexed: 11/26/2022]
Abstract
The Phenylketonuria (PKU) Demographics, Outcomes and Safety (PKUDOS) registry is designed to provide longitudinal safety and efficacy data on subjects with PKU who are (or have been) treated with sapropterin dihydrochloride. The PKUDOS population consists of 1189 subjects with PKU: N = 504 who were continuously exposed to sapropterin from date of registry enrollment, N = 211 who had intermittent exposure to the drug, and N = 474 with some other duration of exposure. Subjects continuously exposed to sapropterin showed an average 34% decrease in blood phenylalanine (Phe)--from 591 ± 382 μmol/L at baseline to 392 ± 239 μmol/L (p = 0.0009) after 5 years. This drop in blood Phe was associated with an increase in dietary Phe tolerance [from 1000 ± 959 mg/day (pre-sapropterin baseline) to 1539 ± 840 mg/day after 6 years]. Drug-related adverse events (AEs) were reported in 6% of subjects, were mostly considered non-serious, and were identified in the gastrointestinal, respiratory, and nervous systems. Serious drug-related AEs were reported in ≤ 1% of subjects. Similar safety and efficacy data were observed for children<4 years. Long-term data from the PKUDOS registry suggest that sapropterin has a tolerable safety profile and that continuous use is associated with a significant and persistent decrease in blood Phe and improvements in dietary Phe tolerance.
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Affiliation(s)
- Nicola Longo
- University of Utah, Division of Medical Genetics, Salt Lake City, UT 84108, USA
| | - Georgianne L Arnold
- University of Pittsburgh School of Medicine, Department of Pediatrics, Children's Hospital of Pittsburgh, Pittsburgh, PA 15238, USA
| | - Gabriella Pridjian
- Tulane University School of Medicine, Hayward Genetics Center, New Orleans, LA 70112, USA
| | - Gregory M Enns
- Stanford University, Division of Medical Genetics, Stanford, CA 94305-5208, USA
| | - Can Ficicioglu
- The Children's Hospital of Philadelphia, Perelman School of Medicine,University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Susan Parker
- BioMarin Pharmaceutical Inc., 105 Digital Drive, Novato, CA 94949, USA
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26
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Comparison of tandem mass spectrometry and amino acid analyzer for phenylalanine and tyrosine monitoring—Implications for clinical management of patients with hyperphenylalaninemia. Clin Biochem 2015; 48:14-8. [DOI: 10.1016/j.clinbiochem.2014.09.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 09/11/2014] [Accepted: 09/14/2014] [Indexed: 11/23/2022]
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27
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Dried blood spot analysis to assess medication adherence and to inform personalization of treatment. Bioanalysis 2014; 6:2825-38. [DOI: 10.4155/bio.14.189] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Little research using dried blood spot samples to assess adherence to medication has been reported. The World Health Organisation estimates that only half of the patients in the developed world take their medication as prescribed. Additional costs to the healthcare provider include wasted medicines, avoidable additional hospital visits and non-optimum patient care. There is little evidence of information concerning medication adherence being made available to inform clinical decision making. In this article we explore the potential of the dried blood spot sample collection methodology as a means of identifying medication adherence to facilitate medicines optimization for a range of disparate diseases. Furthermore, the opportunity to personalize healthcare for different patients by assessing the clinically necessary therapeutic level of the relevant drugs is highlighted.
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28
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Longo N, Harding CO, Burton BK, Grange DK, Vockley J, Wasserstein M, Rice GM, Dorenbaum A, Neuenburg JK, Musson DG, Gu Z, Sile S. Single-dose, subcutaneous recombinant phenylalanine ammonia lyase conjugated with polyethylene glycol in adult patients with phenylketonuria: an open-label, multicentre, phase 1 dose-escalation trial. Lancet 2014; 384:37-44. [PMID: 24743000 PMCID: PMC4447208 DOI: 10.1016/s0140-6736(13)61841-3] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Phenylketonuria is an inherited disease caused by impaired activity of phenylalanine hydroxylase, the enzyme that converts phenylalanine to tyrosine, leading to accumulation of phenylalanine and subsequent neurocognitive dysfunction. Phenylalanine ammonia lyase is a prokaryotic enzyme that converts phenylalanine to ammonia and trans-cinnamic acid. We aimed to assess the safety, tolerability, pharmacokinetic characteristics, and efficacy of recombinant Anabaena variabilis phenylalanine ammonia lyase (produced in Escherichia coli) conjugated with polyethylene glycol (rAvPAL-PEG) in reducing phenylalanine concentrations in adult patients with phenylketonuria. METHODS In this open-label, phase 1, multicentre trial, single subcutaneous injections of rAvPAL-PEG were given in escalating doses (0·001, 0·003, 0·010, 0·030, and 0·100 mg/kg) to adults with phenylketonuria. Participants aged 18 years or older with blood phenylalanine concentrations of 600 μmol/L or higher were recruited from among patients attending metabolic disease clinics in the USA. The primary endpoints were safety and tolerability of rAvPAL-PEG. Secondary endpoints were the pharmacokinetic characteristics of the drug and its effect on concentrations of phenylalanine. Participants and investigators were not masked to assigned dose group. This study is registered with ClinicalTrials.gov, number NCT00925054. FINDINGS 25 participants were recruited from seven centres between May 6, 2008, and April 15, 2009, with five participants assigned to each escalating dose group. All participants were included in the safety population. The most frequently reported adverse events were injection-site reactions and dizziness, which were self-limited and without sequelae. Two participants had serious adverse reactions to intramuscular medroxyprogesterone acetate, a drug that contains polyethylene glycol as an excipient. Three of five participants given the highest dose of rAvPAL-PEG (0·100 mg/kg) developed a generalised skin rash. By the end of the study, all participants had developed antibodies against polyethylene glycol, and some against phenylalanine ammonia lyase as well. Drug concentrations peaked about 89-106 h after administration of the highest dose. Treatment seemed to be effective at reducing blood phenylalanine in all five participants who received the highest dose (mean reduction of 54·2% from baseline), with a nadir about 6 days after injection and an inverse correlation between drug and phenylalanine concentrations in plasma. Phenylalanine returned to near-baseline concentrations about 21 days after the injection. INTERPRETATION Subcutaneous administration of rAvPAL-PEG in a single dose of up to 0·100 mg/kg was fairly safe and well tolerated in adult patients with phenylketonuria. At the highest dose tested, rAvPAL-PEG reduced blood phenylalanine concentrations. In view of the development of antibodies against polyethylene glycol (and in some cases against phenylalanine ammonia lyase), future studies are needed to assess the effect of repeat dosing. FUNDING BioMarin Pharmaceutical.
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Affiliation(s)
| | | | - Barbara K Burton
- Ann and Robert H Lurie Children's Hospital and Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | | | - Jerry Vockley
- University of Pittsburgh School of Medicine, PA, USA
| | | | | | | | | | | | | | - Saba Sile
- BioMarin Pharmaceutical, Novato, CA, USA
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29
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Grange DK, Hillman RE, Burton BK, Yano S, Vockley J, Fong CT, Hunt J, Mahoney JJ, Cohen-Pfeffer JL. Sapropterin dihydrochloride use in pregnant women with phenylketonuria: an interim report of the PKU MOMS sub-registry. Mol Genet Metab 2014; 112:9-16. [PMID: 24667082 DOI: 10.1016/j.ymgme.2014.02.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 02/27/2014] [Indexed: 11/17/2022]
Abstract
For pregnant women with phenylketonuria (PKU), maintaining blood phenylalanine (Phe)<360μmol/L is critical due to the toxicity of elevated Phe to the fetus. Sapropterin dihydrochloride (sapropterin) lowers blood Phe in tetrahydrobiopterin (BH4) responsive patients with PKU, in conjunction with a Phe-restricted diet, but clinical evidence supporting its use during pregnancy is limited. As of June 3, 2013, the Maternal Phenylketonuria Observational Program (PKU MOMS) sub-registry contained data from 21 pregnancies - in women with PKU who were treated with sapropterin either before (N=5) or during (N=16) pregnancy. Excluding data for spontaneous abortions (N=4), the data show that the mean of median blood Phe [204.7±126.6μmol/L (n=14)] for women exposed to sapropterin during pregnancy was 23% lower, and had a 58% smaller standard deviation, compared to blood Phe [267.4±300.7μmol/L (n=3)] for women exposed to sapropterin prior to pregnancy. Women on sapropterin during pregnancy experienced fewer blood Phe values above the recommended 360μmol/L threshold. When median blood Phe concentration was <360μmol/L throughout pregnancy, 75% (12/16) of pregnancy outcomes were normal compared to 40% (2/5) when median blood Phe was >360μmol/L. Severe adverse events identified by the investigators as possibly related to sapropterin use were premature labor (N=1) and spontaneous abortion (N=1) for the women and hypophagia for the offspring [premature birth (35w4d), N=1]. One congenital malformation (cleft palate) of unknown etiology was reported as unrelated to sapropterin. Although there is limited information regarding the use of sapropterin during pregnancy, these sub-registry data show that sapropterin was generally well-tolerated and its use during pregnancy was associated with lower mean blood Phe. Because the teratogenicity of elevated maternal blood Phe is without question, sapropterin should be considered as a treatment option in pregnant women with PKU who cannot achieve recommended ranges of blood Phe with dietary therapy alone.
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Affiliation(s)
- Dorothy K Grange
- Washington University School of Medicine, One Children's Place, NWT 9th Floor, St. Louis, MO 63110, USA
| | - Richard E Hillman
- University of Missouri Health Care, One Hospital Drive, University of Missouri, Columbia, MO 65212, USA
| | - Barbara K Burton
- Ann and Robert H. Lurie Children's Hospital of Chicago, 225 E. Chicago Ave., Box #59, Chicago, IL 60611-2605, USA
| | - Shoji Yano
- Los Angeles County & University of Southern California Medical Center, 1801 Marengo Street, Rm 1G-24, Los Angeles, CA 90033, USA
| | - Jerry Vockley
- University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh, 4401 Penn Ave, Pittsburgh, PA 15224, USA; University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA 15224, USA
| | - Chin-To Fong
- University of Rochester Medical Center, Clinic of Inherited Metabolic Disease, Box 777, Genetics 601, Elmwood Avenue, Rochester, NY 14642-8315, USA
| | - Joellen Hunt
- BioMarin Pharmaceutical Inc., 105 Digital Drive, Novato, CA 94949, USA
| | - John J Mahoney
- BioMarin Pharmaceutical Inc., 105 Digital Drive, Novato, CA 94949, USA
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30
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Vockley J, Andersson HC, Antshel KM, Braverman NE, Burton BK, Frazier DM, Mitchell J, Smith WE, Thompson BH, Berry SA. Phenylalanine hydroxylase deficiency: diagnosis and management guideline. Genet Med 2014; 16:188-200. [PMID: 24385074 DOI: 10.1038/gim.2013.157] [Citation(s) in RCA: 416] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 08/29/2013] [Indexed: 11/08/2022] Open
Abstract
Phenylalanine hydroxylase deficiency, traditionally known as phenylketonuria, results in the accumulation of phenylalanine in the blood of affected individuals and was the first inborn error of metabolism to be identified through population screening. Early identification and treatment prevent the most dramatic clinical sequelae of the disorder, but new neurodevelopmental and psychological problems have emerged in individuals treated from birth. The additional unanticipated recognition of a toxic effect of elevated maternal phenylalanine on fetal development has added to a general call in the field for treatment for life. Two major conferences sponsored by the National Institutes of Health held >10 years apart reviewed the state of knowledge in the field of phenylalanine hydroxylase deficiency, but there are no generally accepted recommendations for therapy. The purpose of this guideline is to review the strength of the medical literature relative to the treatment of phenylalanine hydroxylase deficiency and to develop recommendations for diagnosis and therapy of this disorder. Evidence review from the original National Institutes of Health consensus conference and a recent update by the Agency for Healthcare Research and Quality was used to address key questions in the diagnosis and treatment of phenylalanine hydroxylase deficiency by a working group established by the American College of Medical Genetics and Genomics. The group met by phone and in person over the course of a year to review these reports, develop recommendations, and identify key gaps in our knowledge of this disorder. Above all, treatment of phenylalanine hydroxylase deficiency must be life long, with a goal of maintaining blood phenylalanine in the range of 120-360 µmol/l. Treatment has predominantly been dietary manipulation, and use of low protein and phenylalanine medical foods is likely to remain a major component of therapy for the immediate future. Pharmacotherapy for phenylalanine hydroxylase deficiency is in early stages with one approved medication (sapropterin, a derivative of the natural cofactor of phenylalanine hydroxylase) and others under development. Eventually, treatment of phenylalanine hydroxylase deficiency will be individualized with multiple medications and alternative medical foods available to tailor therapy. The primary goal of therapy should be to lower blood phenylalanine, and any interventions, including medications, or combination of therapies that help to achieve that goal in an individual, without other negative consequences, should be considered appropriate therapy. Significant evidence gaps remain in our understanding of the optimum therapies for phenylalanine hydroxylase deficiency, nonphenylalanine effects of these therapies, and long-term sequelae of even well-treated disease in children and adults.
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Affiliation(s)
- Jerry Vockley
- 1] Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA [2] Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania, USA
| | - Hans C Andersson
- Hayward Genetics Center, Tulane University Medical School, New Orleans, Louisiana, USA
| | - Kevin M Antshel
- Department of Psychology, Syracuse University, Syracuse, New York, USA
| | - Nancy E Braverman
- Department of Human Genetics and Pediatrics, McGill University, Montreal, Quebec, Canada
| | - Barbara K Burton
- Department of Pediatrics, Northwestern University Medical School, Chicago, Illinois, USA
| | - Dianne M Frazier
- Department of Pediatrics, University of North Carolina, at Chapel Hill, Chapel Hill, North Carolina, USA
| | - John Mitchell
- Department of Human Genetics and Pediatrics, McGill University, Montreal, Quebec, Canada
| | - Wendy E Smith
- Department of Pediatrics, Maine Medical Center, Portland, Maine, USA1
| | - Barry H Thompson
- The American College of Medical Genetics and Genomics, Bethesda, Maryland, USA
| | - Susan A Berry
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis, Minnesota, USA
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31
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Pecce R, Scolamiero E, Ingenito L, Parenti G, Ruoppolo M. Optimization of an HPLC method for phenylalanine and tyrosine quantization in dried blood spot. Clin Biochem 2013; 46:1892-5. [DOI: 10.1016/j.clinbiochem.2013.08.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/28/2013] [Accepted: 08/30/2013] [Indexed: 12/11/2022]
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32
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Prinsen HC, Holwerda-Loof NE, de Sain-van der Velden MG, Visser G, Verhoeven-Duif NM. Reliable analysis of phenylalanine and tyrosine in a minimal volume of blood. Clin Biochem 2013; 46:1272-5. [DOI: 10.1016/j.clinbiochem.2013.05.054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 04/10/2013] [Accepted: 05/17/2013] [Indexed: 11/27/2022]
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Seagraves NJ, McBride KL. Cardiac teratogenicity in mouse maternal phenylketonuria: defining phenotype parameters and genetic background influences. Mol Genet Metab 2012; 107:650-8. [PMID: 22951387 PMCID: PMC3504168 DOI: 10.1016/j.ymgme.2012.08.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 08/02/2012] [Accepted: 08/02/2012] [Indexed: 12/23/2022]
Abstract
Maternal phenylketonuria (MPKU) is a syndrome including cardiovascular malformations (CVMs), microcephaly, intellectual impairment, and small size for gestational age, caused by in-utero exposure to elevated serum phenylalanine (Phe) due to PKU in the mother. It is becoming a public health concern as more women with PKU reach child bearing age. Although a mouse model of PKU, BTBR Pah(enu2), has been available for 20 years, it has not been well utilized for studying MPKU. We used this model to delineate critical parameters in Phe cardiovascular teratogenicity and study the effect of genetic background. Dosing and timing experiments were performed with the BTBR Pah(enu2) mouse. A dose response curve was noted, with CVM rates at maternal serum Phe levels <360 μM (control), 360-600 μM (low), 600-900 μM (mid), and >900 μM (high) of 11.86%, 16.67%, 30.86%, and 46.67% respectively. A variety of CVMs were noted on the BTBR background, including double outlet right ventricle (DORV), aortic arch artery (AAA) abnormalities, and ventricular septal defects (VSDs). Timed exposure experiments identified a teratogenic window from embryonic day 8.5-13.5, with higher rates of conotruncal and valve defects occurring in early exposure time and persistent truncus arteriosus (PTA) and aortic arch branching abnormalities occurring with late exposure. Compared to the BTBR strain, N10+ Pah(enu2) congenics on the C3H/HeJ background had higher rates of CVMs in general and propensity to left ventricular outflow tract (LVOT) malformations, while the C57B/L6 background had similar CVM rates but predominately AAA abnormalities. We have delineated key parameters of Phe cardiovascular teratogenicity, demonstrated the utility of this MPKU model on different mouse strains, and shown how genetic background profoundly affects the phenotype.
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Affiliation(s)
- Nikki J Seagraves
- Center for Molecular and Human Genetics, Nationwide Children's Hospital, USA
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Yi S, Kable J, Evatt M, Singh R. A randomized, placebo-controlled, double-blind trial of supplemental docosahexaenoic acid on cognitive processing speed and executive function in females of reproductive age with phenylketonuria: A pilot study. Prostaglandins Leukot Essent Fatty Acids 2011; 85:317-27. [PMID: 22000478 PMCID: PMC4324569 DOI: 10.1016/j.plefa.2011.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2011] [Revised: 09/07/2011] [Accepted: 09/11/2011] [Indexed: 10/16/2022]
Abstract
Low blood docosahexaenoic acid (DHA) is reported in patients with phenylketonuria (PKU); however, the functional implications in adolescents and adults are unknown. This pilot study investigated the effect of supplemental DHA on cognitive performance in 33 females with PKU ages 12-47 years. Participants were randomly assigned to receive DHA (10mg/kg/day) or placebo for 4.5 months. Performance on cognitive processing speed and executive functioning tasks was evaluated at baseline and follow up. Intention-to-treat and per protocol analyses were performed. At follow up, biomarkers of DHA status were significantly higher in the DHA-supplemented group. Performance on the cognitive tasks and reported treatment-related adverse events did not differ. While no evidence of cognitive effect was seen, a larger sample size is needed to be conclusive, which may not be feasible in this population. Supplementation was a safe and effective way to increase biomarkers of DHA status (www.clinicaltrials.gov; Identifier: NCT00892554).
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Affiliation(s)
- S.H.L. Yi
- Emory University, Nutrition & Health Sciences Program of the Graduate Division of Biological & Biomedical Sciences, Atlanta, GA, United States
| | - J.A. Kable
- Emory University, School of Medicine, Department of Pediatrics, United States
| | - M.L. Evatt
- Department of Veterans Affairs Medical Center, Atlanta, GA, United States
- Emory University School of Medicine, Department of Neurology, United States
| | - R.H. Singh
- Emory University, Nutrition & Health Sciences Program of the Graduate Division of Biological & Biomedical Sciences, Atlanta, GA, United States
- Emory University School of Medicine, Department of Human Genetics, 2165 N. Decatur Road, Decatur, GA 30033, United States
- Corresponding author at: Emory University School of Medicine, Department of Human Genetics, 2165 N. Decatur Road, Decatur, GA 30033, United States. Tel.: +1 404 778 8519; fax: +1 404 778 8562. (R.H. Singh)
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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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Viau KS, Wengreen HJ, Ernst SL, Cantor NL, Furtado LV, Longo N. Correlation of age-specific phenylalanine levels with intellectual outcome in patients with phenylketonuria. J Inherit Metab Dis 2011; 34:963-71. [PMID: 21556836 DOI: 10.1007/s10545-011-9329-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 02/18/2011] [Accepted: 03/30/2011] [Indexed: 11/28/2022]
Abstract
Patients with treated phenylketonuria (PKU) can have subtle deficits in intellect, academic skills, and executive functioning. This study evaluates the relationship between intellectual outcome and concentration/variation in blood phenylalanine (Phe) during specific developmental periods (0-6 years, 7-12 years, >12 years) in our patients with PKU. Verbal comprehension, perceptual reasoning, and processing speed were used as measures of intelligence. Data were collected from 55 patients receiving treatment at the University of Utah Metabolic Clinic. Yearly median Phe levels increased and mean number of blood Phe samples decreased as patients aged. Yearly median blood Phe from 0-6 and 7-12 years were inversely associated with perceptual reasoning abilities using linear regression. Additionally, increased blood Phe concentration negatively impacted specific areas of verbal comprehension abilities for those 0-6 years of age (p = 0.001). Variation of Phe levels around the mean (assessed as standard deviation) in each patient was associated with diagnostic (highest pretreatment) Phe levels and yearly median Phe levels (p < 0.001 for both), but did not significantly impact intelligence in our group of patients. Frequent blood Phe monitoring from 7-12 years significantly reduced the probability of yearly median Phe exceeding 360 μM (p = 0.005). Our data show that compliance with treatment in patients with PKU affects both the concentration and variation of blood Phe levels, and may have a greater impact on verbal comprehension and perceptual reasoning skills during the first 12 years of life when compared the influence beyond 12 years.
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Affiliation(s)
- Krista S Viau
- Department Pediatrics, University of Utah, Salt Lake City, UT, USA.
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Quirk ME, Schmotzer BJ, Schmotzer BJ, Singh RH. Predictive equations underestimate resting energy expenditure in female adolescents with phenylketonuria. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION 2010; 110:922-5. [PMID: 20497783 PMCID: PMC2885772 DOI: 10.1016/j.jada.2010.03.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 11/03/2009] [Indexed: 11/19/2022]
Abstract
Resting energy expenditure (REE) is often used to estimate total energy needs. The Schofield equation based on weight and height has been reported to underestimate REE in female children with phenylketonuria (PKU). The objective of this observational, cross-sectional study was to evaluate the agreement of measured REE with predicted REE for female adolescents with PKU. A total of 36 females (aged 11.5 to 18.7 years) with PKU attending Emory University's Metabolic Camp (June 2002 to June 2008) underwent indirect calorimetry. Measured REE was compared to six predictive equations using paired Student's t tests, regression-based analysis, and assessment of clinical accuracy. The differences between measured and predicted REE were modeled against clinical parameters to determine whether a relationship existed. All six selected equations significantly under predicted measured REE (P<0.005). The Schofield equation based on weight had the greatest level of agreement, with the lowest mean prediction bias (144 kcal) and highest concordance correlation coefficient (0.626). However, the Schofield equation based on weight lacked clinical accuracy, predicting measured REE within +/-10% in only 14 of 36 participants. Clinical parameters were not associated with bias for any of the equations. Predictive equations underestimated measured REE in this group of female adolescents with PKU. Currently, there is no accurate and precise alternative for indirect calorimetry in this population.
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Affiliation(s)
- Meghan E. Quirk
- Emory University Graduate Division of Biological & Biomedical Sciences, Nutrition & Health Sciences Emory Genetics Clinic Building 2165 North Decatur Road Decatur, GA 30033 Phone: 404-778-1286 Fax: 404-778-8562
| | - Brian J. Schmotzer
- Emory University Department Biostatistics and Bioinformatics, School of Public Health 1518 Clifton Rd NE, Grace C. Rollins Bldg 349, Mailstop #1518-002-3AA Atlanta, GA 30329 Phone: 404-727-9193 Fax: 404-727-1370
| | - Brian J. Schmotzer
- Center for Clinical Investigation Case Western Reserve University School of Medicine Iris S. & Bert L. Wolstein Building 2103 Cornell Road Cleveland, OH 44106 Phone: 216-368-7560 Fax: 216-368-0207
| | - Rani H. Singh
- Emory Genetics Metabolic Nutrition Program Department of Human Genetics, Emory University School of Medicine Emory Genetics Clinic Building 2165 North Decatur Road Decatur, GA 30033
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De Silva V, Oldham CD, May SW. L-Phenylalanine concentration in blood of phenylketonuria patients: a modified enzyme colorimetric assay compared with amino acid analysis, tandem mass spectrometry, and HPLC methods. Clin Chem Lab Med 2010; 48:1271-9. [DOI: 10.1515/cclm.2010.271] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Ney DM, Gleason ST, van Calcar SC, MacLeod EL, Nelson KL, Etzel MR, Rice GM, Wolff JA. Nutritional management of PKU with glycomacropeptide from cheese whey. J Inherit Metab Dis 2009; 32:32-9. [PMID: 18956251 PMCID: PMC3633220 DOI: 10.1007/s10545-008-0952-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 08/04/2008] [Accepted: 08/30/2008] [Indexed: 10/21/2022]
Abstract
Individuals with phenylketonuria (PKU) must follow a lifelong low-phenylalanine (Phe) diet to prevent neurological impairment. Compliance with the low-Phe diet is often poor owing to restriction in natural foods and the requirement for consumption of a Phe-free amino acid formula or medical food. Glycomacropeptide (GMP), a natural protein produced during cheese-making, is uniquely suited to a low-Phe diet because when isolated from cheese whey it contains minimal Phe (2.5-5 mg Phe/g protein). This paper reviews progress in evaluating the safety, acceptability and efficacy of GMP in the nutritional management of PKU. A variety of foods and beverages can be made with GMP to improve the taste, variety and convenience of the PKU diet. Sensory studies in individuals with PKU demonstrate that GMP foods are acceptable alternatives to amino acid medical foods. Studies in the PKU mouse model demonstrate that GMP supplemented with limiting indispensable amino acids provides a nutritionally adequate source of protein and improves the metabolic phenotype by reducing concentrations of Phe in plasma and brain. A case report in an adult with classical PKU who followed the GMP diet for 10 weeks at home indicates safety, acceptability of GMP food products, a 13-14% reduction in blood Phe levels (p<0.05) and improved distribution of dietary protein throughout the day compared with the amino acid diet. In summary, food products made with GMP that is supplemented with limiting indispensable amino acids provide a palatable alternative source of protein that may improve dietary compliance and metabolic control of PKU.
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Affiliation(s)
- D M Ney
- Department of Nutritional Sciences, University of Wisconsin, Madison, WI 53706, USA.
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