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Turgeon C, Casas K, Flanagan R, White A, Peck D, Pino GB, Jones AS, Gavrilov D, Oglesbee D, Schultz MJ, Tortorelli S, Matern D, Hall PL. Pre-analytic decrease of phenylalanine in plasma of patients with phenylketonuria treated with pegvaliase. Mol Genet Metab Rep 2024; 40:101110. [PMID: 39022300 PMCID: PMC11252920 DOI: 10.1016/j.ymgmr.2024.101110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 06/18/2024] [Accepted: 06/18/2024] [Indexed: 07/20/2024] Open
Abstract
Treatment of phenylketonuria (PKU) has evolved since the initial introduction of a phenylalanine (Phe) restricted diet. The most recent option for adults affected with PKU is treatment with an alternate enzyme, phenylalanine ammonia lyase (PAL), that metabolizes excess Phe. Proper management of all patients with PKU relies on accurate measurement of Phe levels in blood, to comply with guidance intended to minimize the neurological symptoms. Recently, our laboratory was notified of discrepant results for a patient with PKU who is treated with pegvaliase. Two specimens were collected at the same time but yielded unexpectedly different Phe concentrations. After exclusion of specimen mix-ups or analytical errors, we suspected that there was residual pegvaliase activity in the specimens continuing to degrade Phe after collection. To investigate this possibility, we performed spiking studies that showed the degradation of Phe over time at ambient temperatures. Sample preparation by protein crash appears to deactivate pegvaliase and prevents further Phe degradation. However, because pegvaliase deactivation would be required immediately following blood collection, appropriate mitigation measures must be implemented, including stringent pre-analytical requirements, alternate sample matrices such as dried blood spots, or point of care testing. Until then, health care professionals need to be cautious in their interpretation of Phe levels in their patients with PKU that are treated with pegvaliase.
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Affiliation(s)
- Coleman Turgeon
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | | | - Ryan Flanagan
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Amy White
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Dawn Peck
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Gisele Bentz Pino
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | | | - Dimitar Gavrilov
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Devin Oglesbee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Matthew J. Schultz
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Silvia Tortorelli
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Dietrich Matern
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Patricia L. Hall
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
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Pinto A, Ahring K, Almeida MF, Ashmore C, Bélanger-Quintana A, Burlina A, Coşkun T, Daly A, van Dam E, Dursun A, Evans S, Feillet F, Giżewska M, Gökmen-Özel H, Hickson M, Hoekstra Y, Ilgaz F, Jackson R, Leśniak A, Loro C, Malicka K, Patalan M, Rocha JC, Sivri S, Rodenburg I, van Spronsen F, Strączek K, Tokatli A, MacDonald A. Blood Phenylalanine Levels in Patients with Phenylketonuria from Europe between 2012 and 2018: Is It a Changing Landscape? Nutrients 2024; 16:2064. [PMID: 38999811 PMCID: PMC11243388 DOI: 10.3390/nu16132064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/14/2024] Open
Abstract
BACKGROUND In 2011, a European phenylketonuria (PKU) survey reported that the blood phenylalanine (Phe) levels were well controlled in early life but deteriorated with age. Other studies have shown similar results across the globe. Different target blood Phe levels have been used throughout the years, and, in 2017, the European PKU guidelines defined new targets for blood Phe levels. This study aimed to evaluate blood Phe control in patients with PKU across Europe. METHODS nine centres managing PKU in Europe and Turkey participated. Data were collected retrospectively from medical and dietetic records between 2012 and 2018 on blood Phe levels, PKU severity, and medications. RESULTS A total of 1323 patients (age range:1-57, 51% male) participated. Patient numbers ranged from 59 to 320 in each centre. The most common phenotype was classical PKU (n = 625, 48%), followed by mild PKU (n = 357, 27%) and hyperphenylalaninemia (HPA) (n = 325, 25%). The mean percentage of blood Phe levels within the target range ranged from 65 ± 54% to 88 ± 49% for all centres. The percentage of Phe levels within the target range declined with increasing age (<2 years: 89%; 2-5 years: 84%; 6-12 years: 73%; 13-18 years: 85%; 19-30 years: 64%; 31-40 years: 59%; and ≥41 years: 40%). The mean blood Phe levels were significantly lower and the percentage within the target range was significantly higher (p < 0.001) in patients with HPA (290 ± 325 μmol/L; 96 ± 24%) and mild PKU (365 ± 224 μmol/L; 77 ± 36%) compared to classical PKU (458 ± 350 μmol/L, 54 ± 46%). There was no difference between males and females in the mean blood Phe levels (p = 0.939), but the percentage of Phe levels within the target range was higher in females among school-age children (6-12 years; 83% in females vs. 78% in males; p = 0.005), adolescents (13-18 years; 62% in females vs. 59% in males; p = 0.034) and adults (31-40 years; 65% in females vs. 41% in males; p < 0.001 and >41 years; 43% in females vs. 28% in males; p < 0.001). Patients treated with sapropterin (n = 222) had statistically significantly lower Phe levels compared to diet-only-treated patients (mean 391 ± 334 μmol/L; percentage within target 84 ± 39% vs. 406 ± 334 μmol/L; 73 ± 41%; p < 0.001), although a blood Phe mean difference of 15 µmol/L may not be clinically relevant. An increased frequency of blood Phe monitoring was associated with better metabolic control (p < 0.05). The mean blood Phe (% Phe levels within target) from blood Phe samples collected weekly was 271 ± 204 μmol/L, (81 ± 33%); for once every 2 weeks, it was 376 ± 262 μmol/L, (78 ± 42%); for once every 4 weeks, it was 426 ± 282 μmol/L, (71 ± 50%); and less than monthly samples, it was 534 ± 468 μmol/L, (70 ± 58%). CONCLUSIONS Overall, blood Phe control deteriorated with age. A higher frequency of blood sampling was associated with better blood Phe control with less variability. The severity of PKU and the available treatments and resources may impact the blood Phe control achieved by each treatment centre.
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Affiliation(s)
- Alex Pinto
- Birmingham Children’s Hospital, Birmingham B4 6NH, UK; (C.A.); (A.D.); (S.E.); (A.M.)
- School of Health Professions, Faculty of Health, University of Plymouth, Plymouth PL4 8AA, UK;
| | - Kirsten Ahring
- Departments of Paediatrics and Clinical Genetics, PKU Clinic, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark;
| | - Manuela Ferreira Almeida
- Centro de Genética Médica, Unidade Local de Saúde de Santo António, E.P.E. (ULSSA), 4099-028 Porto, Portugal;
- Centro de Referência na área de Doenças Hereditárias do Metabolismo, Unidade Local de Saúde de Santo António, E.P.E. (ULSSA), 4099-001 Porto, Portugal
- Unit for Multidisciplinary Research in Biomedicine, Abel Salazar Institute of Biomedical Sciences, University of Porto-UMIB/ICBAS/UP, 4050-313 Porto, Portugal
| | - Catherine Ashmore
- Birmingham Children’s Hospital, Birmingham B4 6NH, UK; (C.A.); (A.D.); (S.E.); (A.M.)
| | - Amaya Bélanger-Quintana
- Unidad de Enfermedades Metabólicas Congénitas, Hospital Universitario Ramón y Cajal, 28034 Madrid, Spain;
| | - Alberto Burlina
- Division of Inherited Metabolic Diseases, Reference Centre Expanded Newborn Screening, Department of Women’s and Children’s Health, University Hospital, 35128 Padova, Italy; (A.B.); (C.L.)
| | - Turgay Coşkun
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Gevher Nesibe Cd., 06230 Ankara, Turkey; (T.C.); (A.D.); (S.S.); (A.T.)
| | - Anne Daly
- Birmingham Children’s Hospital, Birmingham B4 6NH, UK; (C.A.); (A.D.); (S.E.); (A.M.)
| | - Esther van Dam
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9700 RB Groningen, The Netherlands; (E.v.D.); (Y.H.); (I.R.); (F.v.S.)
| | - Ali Dursun
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Gevher Nesibe Cd., 06230 Ankara, Turkey; (T.C.); (A.D.); (S.S.); (A.T.)
| | - Sharon Evans
- Birmingham Children’s Hospital, Birmingham B4 6NH, UK; (C.A.); (A.D.); (S.E.); (A.M.)
| | - François Feillet
- Department of Paediatrics, Reference Center for Inborn Errors of Metabolism, Hôpital d’Enfants Brabois, CHU Nancy, 54500 Vandoeuvre les Nancy, France;
| | - Maria Giżewska
- Department of Pediatrics, Endocrinology, Diabetology, Metabolic Diseases and Cardiology, Pomeranian Medical University, 70-204 Szczecin, Poland; (M.G.); (A.L.); (K.M.); (M.P.); (K.S.)
| | - Hulya Gökmen-Özel
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Hacettepe University, 06100 Ankara, Turkey; (H.G.-Ö.); (F.I.)
| | - Mary Hickson
- School of Health Professions, Faculty of Health, University of Plymouth, Plymouth PL4 8AA, UK;
| | - Yteke Hoekstra
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9700 RB Groningen, The Netherlands; (E.v.D.); (Y.H.); (I.R.); (F.v.S.)
| | - Fatma Ilgaz
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Hacettepe University, 06100 Ankara, Turkey; (H.G.-Ö.); (F.I.)
| | - Richard Jackson
- Cancer Research UK Liverpool Cancer Trials Unit, University of Liverpool, Liverpool L69 3GL, UK;
| | - Alicja Leśniak
- Department of Pediatrics, Endocrinology, Diabetology, Metabolic Diseases and Cardiology, Pomeranian Medical University, 70-204 Szczecin, Poland; (M.G.); (A.L.); (K.M.); (M.P.); (K.S.)
| | - Christian Loro
- Division of Inherited Metabolic Diseases, Reference Centre Expanded Newborn Screening, Department of Women’s and Children’s Health, University Hospital, 35128 Padova, Italy; (A.B.); (C.L.)
| | - Katarzyna Malicka
- Department of Pediatrics, Endocrinology, Diabetology, Metabolic Diseases and Cardiology, Pomeranian Medical University, 70-204 Szczecin, Poland; (M.G.); (A.L.); (K.M.); (M.P.); (K.S.)
| | - Michał Patalan
- Department of Pediatrics, Endocrinology, Diabetology, Metabolic Diseases and Cardiology, Pomeranian Medical University, 70-204 Szczecin, Poland; (M.G.); (A.L.); (K.M.); (M.P.); (K.S.)
| | - Júlio César Rocha
- Nutrition and Metabolism, NOVA Medical School (NMS), Faculdade de Ciências Médicas, (FCM), Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal;
- Centro de Investigação em Tecnologias e Serviços de Saúde (CINTESIS), NOVA Medical School (NMS), Faculdade de Ciências Médicas, (FCM), Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal
- Reference Centre of Inherited Metabolic Diseases, Unidade Local de Saúde, 1169-045 Lisboa, Portugal
- Comprehensive Health Research Centre (CHRC), NOVA Medical School, (NMS), Faculdade de Ciências Médicas (FCM), Universidade Nova de Lisboa, 1169-056 Lisboa, Portugal
| | - Serap Sivri
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Gevher Nesibe Cd., 06230 Ankara, Turkey; (T.C.); (A.D.); (S.S.); (A.T.)
| | - Iris Rodenburg
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9700 RB Groningen, The Netherlands; (E.v.D.); (Y.H.); (I.R.); (F.v.S.)
| | - Francjan van Spronsen
- Division of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9700 RB Groningen, The Netherlands; (E.v.D.); (Y.H.); (I.R.); (F.v.S.)
| | - Kamilla Strączek
- Department of Pediatrics, Endocrinology, Diabetology, Metabolic Diseases and Cardiology, Pomeranian Medical University, 70-204 Szczecin, Poland; (M.G.); (A.L.); (K.M.); (M.P.); (K.S.)
| | - Ayşegül Tokatli
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Gevher Nesibe Cd., 06230 Ankara, Turkey; (T.C.); (A.D.); (S.S.); (A.T.)
| | - Anita MacDonald
- Birmingham Children’s Hospital, Birmingham B4 6NH, UK; (C.A.); (A.D.); (S.E.); (A.M.)
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