RESUMEN
BACKGROUND: Phenylketonuria is an inherited condition characterised by neurotoxic accumulation of phenylalanine (Phe). APHENITY assessed the efficacy and safety of orally administered synthetic sepiapterin in children and adults with phenylketonuria. METHODS: APHENITY was a phase 3, randomised, double-blind, placebo-controlled study performed at 34 clinics, hospitals, and university sites in 13 countries. Individuals of all ages with a clinical diagnosis of phenylketonuria were eligible for inclusion if they had a blood Phe concentration of 360 µmol/L or higher at study entry, whereas individuals with hyperphenylalaninaemia due to pathogenic variants in GCH1, PTS, QDPR, SPR, and PCBD1, consistent with a diagnosis of primary BH4 deficiency, were excluded. Part 1 was a 14-day open-label assessment of blood Phe concentration response to sepiapterin. In part 2, sepiapterin-responsive participants were randomly assigned (1:1) by a web-response system based on a block randomisation schedule (permuted block size of 2 and 4) to 6 weeks of sepiapterin (forced-dose escalation: 20, 40, and 60 mg/kg per day per consecutive 2-week period) or placebo. The investigational drug and placebo were identical in their appearance and delivery. Dried blood samples were collected for analysis of Phe concentration on days -1, 1 (before dose was administered), 5, 10, 14, 19, 24, 28, 33, 38, and 42 in part 2, either in-clinic or at home. The primary endpoint for part 2, mean change from baseline in blood Phe after 6 weeks, was assessed in the primary analysis set of participants with at least a 30% reduction in blood Phe concentration in part 1, who took at least one dose in part 2. Safety was evaluated in all participants receiving at least one dose of treatment. The completed study is registered at EudraCT (2021-000474-29) and ClinicalTrials.gov (NCT05099640). FINDINGS: APHENITY was conducted between Sept 30, 2021, and April 3, 2023. 187 people were assessed for eligibility, of whom 157 were enrolled. In part 1, 156 participants were assessed or evaluated, of whom 114 (73%) were sepiapterin-responsive (ie, ≥15% reduction in blood Phe from baseline). In part 2, 98 participants (49 in the placebo group and 49 in the sepiapterin group) were in the primary analysis set. There was a significant reduction of blood Phe concentration after 6 weeks of sepiapterin (-63%, SD 20) compared with placebo (1%, 29; least squares mean change -395·9 µmol/L, SE 33·8; p<0·0001). Treatment-emergent adverse events were reported in 33 (59%) of 56 participants who received sepiapterin and 18 (33%) of 54 participants who received placebo. Most treatment-emergent adverse events were mild gastrointestinal events (11 [20%] of 56 participants who received sepiapterin and ten [19%] of 54 participants who received placebo) that resolved quickly. There were no deaths and no serious or severe adverse events. INTERPRETATION: Sepiapterin is a promising oral therapy for individuals with phenylketonuria, was well tolerated, and resulted in significant and clinically meaningful reductions in blood Phe concentration in participants with varying disease severity. FUNDING: PTC Therapeutics.
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Fenilalanina , Fenilcetonurias , Pterinas , Adolescente , Adulto , Niño , Preescolar , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Administración Oral , Método Doble Ciego , Fenilalanina/sangre , Fenilcetonurias/tratamiento farmacológico , Fenilcetonurias/sangre , Pterinas/uso terapéutico , Resultado del TratamientoRESUMEN
BACKGROUND: Assessing dietary phenylalanine (Phe) tolerance is crucial for managing hyperphenylalaninemia (HPA) in children. However, traditionally, adjusting the diet requires significant time from clinicians and parents. This study aims to investigate the development of a machine-learning model that predicts a range of dietary Phe intake tolerance for children with HPA over 10 years following diagnosis. METHODS: In this multicenter retrospective observational study, we collected the genotypes of phenylalanine hydroxylase (PAH), metabolic profiles at screening and diagnosis, and blood Phe concentrations corresponding to dietary Phe intake from over 10 years of follow-up data for 204 children with HPA. To incorporate genetic information, allelic phenotype value (APV) was input for 2965 missense variants in the PAH gene using a predicted APV (pAPV) model. This model was trained on known pheno-genotype relationships from the BioPKU database, utilizing 31 features. Subsequently, a multiclass classification model was constructed and trained on a dataset featuring metabolic data, genetic data, and follow-up data from 3177 events. The final model was fine-tuned using tenfold validation and validated against three independent datasets. RESULTS: The pAPV model achieved a good predictive performance with root mean squared error (RMSE) of 1.53 and 2.38 on the training and test datasets, respectively. The variants that cause amino acid changes in the region of 200-300 of PAH tend to exhibit lower pAPV. The final model achieved a sensitivity range of 0.77 to 0.91 and a specificity range of 0.8 to 1 across all validation datasets. Additional assessment metrics including positive predictive value (0.68-1), negative predictive values (0.8-0.98), F1 score (0.71-0.92), and balanced accuracy (0.8-0.92) demonstrated the robust performance of our model. CONCLUSIONS: Our model integrates metabolic and genetic information to accurately predict age-specific Phe tolerance, aiding in the precision management of patients with HPA. This study provides a potential framework that could be applied to other inborn errors of metabolism.
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Aprendizaje Automático , Fenilcetonurias , Humanos , Estudios Retrospectivos , Fenilcetonurias/dietoterapia , Fenilcetonurias/genética , Fenilcetonurias/diagnóstico , Niño , Masculino , Femenino , Preescolar , Fenilalanina Hidroxilasa/genética , Fenilalanina/sangre , Lactante , Genotipo , AdolescenteRESUMEN
BACKGROUND: Due to newborn screening and early treatment, patients with phenylketonuria (PKU) and mild hyperphenylalaninemia (mHPA) develop largely normal, in terms of IQ testing and academic attainment. However, the impact of metabolic control in various stages of development on more complex cognitive abilities, i.e. executive functions (EF), is still unclear. METHODS: EFs were tested in 28 patients with PKU/mHPA, aged 8-17 years, identified by newborn screening and continuously treated. The relation to current (testing day & past 10 phenylalanine (Phe) values) and long-term metabolic control (age periods: childhood <6, 6-10, adolescence >10 years, lifetime Phe) was analyzed. RESULTS: EFs were in the lower normative range (IQR of T-values: 47.35-51.00). Patients reaction time was significantly slower than the population mean (divided attention/TAP: median 40, p < 0.01). Both, long-term and current metabolic control correlated with performance in EF tests: Higher current Phe impaired reaction times (Go/No-Go, r = -0.387; working memory, r = -0.425; p < 0.05) and performance in planning ability (ToL r = -0.465, p < 0.01). Higher long-term Phe values both in childhood and adolescence mainly affected attention (omissions/TAP r = -0.357 and - 0.490, respectively, both p < 0.05) as well as planning ability (ToL r = -0.422 and - 0.387, adolescence and lifetime, p < 0.05). CONCLUSION: Current and long-term metabolic control in PKU/mHPA, including the adolescent period, influence EFs, especially affecting reaction time and planning abilities. This should be taken into account in patient counselling.
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Función Ejecutiva , Fenilcetonurias , Función Ejecutiva/fisiología , Fenilcetonurias/genética , Fenilcetonurias/metabolismo , Fenilcetonurias/patología , Humanos , Masculino , Femenino , Niño , Adolescente , Fenilalanina/sangre , Pruebas Neuropsicológicas , Cumplimiento y Adherencia al TratamientoRESUMEN
Over fifty years have passed since the last large scale longitudinal study of individuals with PAH deficiency in the U.S. Since then, there have been significant changes in terms of treatment recommendations as well as treatment options. The Phenylalanine Families and Researchers Exploring Evidence (PHEFREE) Consortium was recently established to collect a more up-to-date and extensive longitudinal natural history in individuals with phenylketonuria across the lifespan. In the present paper, we describe the structure and methods of the PHEFREE longitudinal study protocol and report cross-sectional data from an initial sample of 73 individuals (5 months to 54 years of age) with PAH deficiency who have enrolled. Looking forward, the study holds the promise for advancing the field on several fronts including the validation of novel neurocognitive tools for assessment in individuals with PKU as well as evaluation of the long-term effects of changes in metabolic control (e.g., effects of Phe-lowering therapies) on outcome.
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Fenilalanina Hidroxilasa , Fenilalanina , Fenilcetonurias , Humanos , Fenilcetonurias/genética , Fenilcetonurias/patología , Estudios Longitudinales , Estudios Transversales , Masculino , Niño , Adolescente , Femenino , Adulto , Lactante , Preescolar , Persona de Mediana Edad , Fenilalanina Hidroxilasa/genética , Fenilalanina Hidroxilasa/deficiencia , Fenilalanina/sangre , Fenilalanina/metabolismo , Adulto JovenRESUMEN
INTRODUCTION: Phenylketonuria (PKU) requires regular phenylalanine monitoring to ensure optimal outcome. However, home sampling methods used for monitoring suffer high pre-analytical variability, inter-laboratory variability and turn-around-times, highlighting the need for alternative methods of home sampling or monitoring. METHODS: A survey was distributed through email and social media to (parents of) PKU patients and professionals working in inherited metabolic diseases in Denmark, The Netherlands, and United Kingdom regarding satisfaction with current home sampling methods and expectations for future point-of-care testing (POCT). RESULTS: 210 parents, 156 patients and 95 professionals completed the survey. Countries, and parents and patients were analysed together, in absence of significant group differences for most questions. Important results are: 1) Many patients take less home samples than advised. 2) The majority of (parents of) PKU patients are (somewhat) dissatisfied with their home sampling method, especially with turn-around-times (3-5 days). 3) 37% of professionals are dissatisfied with their home sampling method and 45% with the turn-around-times. 4) All responders are positive towards developments for POCT: 97% (n = 332) of (parents of) patients is willing to use a POC-device and 76% (n = 61) of professionals would recommend their patients to use a POC-device. 5) Concerns from all participants for future POC-devices are costs/reimbursements and accuracy, and to professionals specifically, accessibility to results, over-testing, patient anxiety, and patients adjusting their diet without consultation. CONCLUSION: The PKU community is (somewhat) dissatisfied with current home sampling methods, highlighting the need for alternatives of Phe monitoring. POCT might be such an alternative and the community is eager for its arrival.
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Padres , Fenilcetonurias , Pruebas en el Punto de Atención , Humanos , Fenilcetonurias/diagnóstico , Fenilcetonurias/sangre , Masculino , Femenino , Encuestas y Cuestionarios , Padres/psicología , Recolección de Muestras de Sangre , Reino Unido , Países Bajos , Adulto , Satisfacción del Paciente , Fenilalanina/sangre , Dinamarca , Niño , AdolescenteRESUMEN
Despite numerous studies in human patients and animal models for phenylketonuria (PKU; OMIM#261600), the pathophysiology of PKU and the underlying causes of brain dysfunction and cognitive problems in PKU patients are not well understood. In this study, lumbar cerebral spinal fluid (CSF) was obtained immediately after blood sampling from early-treated adult PKU patients who had fasted overnight. Metabolite and amino acid concentrations in the CSF of PKU patients were compared with those of non-PKU controls. The CSF concentrations and CSF/plasma ratios for glucose and lactate were found to be below normal, similar to what has been reported for glucose transporter1 (GLUT1) deficiency patients who exhibit many of the same clinical symptoms as untreated PKU patients. CSF glucose and lactate levels were negatively correlated with CSF phenylalanine (Phe), while CSF glutamine and glutamate levels were positively correlated with CSF Phe levels. Plasma glucose levels were negatively correlated with plasma Phe concentrations in PKU subjects, which partly explains the reduced CSF glucose concentrations. Although brain glucose concentrations are unlikely to be low enough to impair brain glucose utilization, it is possible that the metabolism of Phe in the brain to produce phenyllactate, which can be transported across the blood-brain barrier to the blood, may consume glucose and/or lactate to generate the carbon backbone for glutamate. This glutamate is then converted to glutamine and carries the Phe-derived ammonia from the brain to the blood. While this mechanism remains to be tested, it may explain the correlations of CSF glutamine, glucose, and lactate concentrations with CSF Phe.
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Encéfalo , Glucosa , Fenilalanina , Fenilcetonurias , Humanos , Fenilcetonurias/metabolismo , Fenilcetonurias/líquido cefalorraquídeo , Glucosa/metabolismo , Adulto , Masculino , Fenilalanina/líquido cefalorraquídeo , Fenilalanina/sangre , Fenilalanina/metabolismo , Femenino , Encéfalo/metabolismo , Ácido Láctico/líquido cefalorraquídeo , Ácido Láctico/metabolismo , Ácido Láctico/sangre , Adulto Joven , Glutamina/metabolismo , Glutamina/líquido cefalorraquídeo , Glutamina/sangre , Glucemia/metabolismoRESUMEN
Phenylketonuria (PKU) is a congenital metabolic disorder that causes the systemic elevation of phenylalanine (Phe), which is neurotoxic and teratogenic. PKU is currently incurable, and management involves lifelong adherence to an unpalatable protein-restricted diet based on Phe-free amino acid mixtures. Seeking a palatable dietary alternative, we identified a Bacillus subtilis protein (GSP16O) with a well-balanced but low-Phe amino acid profile. We optimized the sequence and expressed a modified Phe-free version (GSP105) in Pseudomonas fluorescens, achieving yields of 20 g/L. The purified GSP105 protein has a neutral taste and smell, is highly soluble, and remains stable up to 80°C. Homozygous enu2 mice, a model of human PKU, were fed with diets containing either GSP105 or normal protein. The GSP105 diet led to normalization of blood Phe levels and brain monoamine neurotransmitter metabolites, and prevented maternal PKU. The GSP105 diet thus provides an alternative and efficacious dietary management strategy for PKU.
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Fenilalanina , Fenilcetonurias , Proteínas Recombinantes , Fenilalanina/sangre , Animales , Fenilcetonurias/dietoterapia , Ratones , Humanos , Proteínas Recombinantes/administración & dosificación , Femenino , Modelos Animales de Enfermedad , Bacillus subtilis/metabolismo , Bacillus subtilis/genética , Proteínas en la Dieta/administración & dosificación , Dieta con Restricción de Proteínas , Proteínas Bacterianas/genéticaRESUMEN
Recent studies in PKU patients identified alternative biomarkers in blood using untargeted metabolomics. To test the added clinical value of these novel biomarkers, targeted metabolomics of 11 PKU biomarkers (phenylalanine, glutamyl-phenylalanine, glutamyl-glutamyl-phenylalanine, N-lactoyl-phenylalanine, N-acetyl-phenylalanine, the dipeptides phenylalanyl-phenylalanine and phenylalanyl-leucine, phenylalanine-hexose conjugate, phenyllactate, phenylpyruvate, and phenylacetate) was performed in stored serum samples of the well-defined PKU patient-COBESO cohort and a healthy control group. Serum samples of 35 PKU adults and 20 healthy age- and sex-matched controls were analyzed using ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry. Group differences were tested using the Mann-Whitney U test. Multiple linear regression analyses were performed with these biomarkers as predictors of (neuro-)cognitive functions working memory, sustained attention, inhibitory control, and mental health. Compared to healthy controls, phenylalanine, glutamyl-phenylalanine, N-lactoyl-phenylalanine, N-acetyl-phenylalanine, phenylalanine-hexose conjugate, phenyllactate, phenylpyruvate, and phenylacetate were significant elevated in PKU adults (p < 0.001). The remaining three were below limit of detection in PKU and controls. Both phenylalanine and N-lactoyl-phenylalanine were associated with DSM-VI Attention deficit/hyperactivity (R2 = 0.195, p = 0.039 and R2 = 0.335, p = 0.002, respectively) of the ASR questionnaire. In addition, N-lactoyl-phenylalanine showed significant associations with ASR DSM-VI avoidant personality (R2 = 0.265, p = 0.010), internalizing (R2 = 0.192, p = 0.046) and externalizing problems (R2 = 0.217, p = 0.029) of the ASR questionnaire and multiple aspects of the MS2D and FI tests, reflecting working memory with R2 between 0.178 (p = 0.048) and 0.204 (p = 0.033). Even though the strength of the models was not considered strong, N-lactoyl-phenylalanine outperformed phenylalanine in its association with working memory and mental health outcomes.
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Biomarcadores , Fenilalanina , Fenilcetonurias , Humanos , Fenilcetonurias/sangre , Biomarcadores/sangre , Adulto , Masculino , Femenino , Adulto Joven , Estudios de Casos y Controles , Fenilalanina/sangre , Metabolómica/métodos , Cromatografía Líquida de Alta Presión , Relevancia ClínicaRESUMEN
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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Biopterinas , Fenilalanina , Fenilcetonurias , Resultado del Embarazo , Sistema de Registros , Humanos , Embarazo , Femenino , Adulto , Fenilalanina/sangre , Biopterinas/análogos & derivados , Biopterinas/uso terapéutico , Biopterinas/efectos adversos , Recién Nacido , Fenilcetonurias/tratamiento farmacológico , Fenilcetonurias/sangre , Fenilcetonuria Materna/tratamiento farmacológico , Adulto Joven , Europa (Continente) , Complicaciones del Embarazo/tratamiento farmacológico , Complicaciones del Embarazo/sangreRESUMEN
Background and Objectives: Phenylketonuria (PKU) is a rare genetic disorder characterized by the inability to convert the essential amino acid phenylalanine into tyrosine. Early dietary treatment can successfully prevent complications, but controversies still exist regarding the attainment of normal growth in these patients. Materials and Methods: Eighteen patients with PKU from two Romanian reference centers were compared to eighteen non-PKU controls, matched for age and gender. The comparisons used weight-for-height, weight-for-age, height/length-for-age, and body mass index-for-age z-scores from birth to three years of age. Results: The PKU study group consisted of nine boys and nine girls, with a median follow-up period of thirty-six months (interquartile range = 9.75). While median values of all four growth metrics remained within the normal range across the entire study period, weight-for-age z-scores were significantly lower in PKU patients throughout most of the study (p < 0.001). Conclusions: The persistent lower weight-for-age z-scores of the PKU patients compared to controls indicate that ongoing monitoring and potential adjustments in dietary therapy may be necessary to further optimize growth outcomes.
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Fenilcetonurias , Humanos , Fenilcetonurias/dietoterapia , Masculino , Rumanía , Femenino , Estudios Retrospectivos , Preescolar , Estudios Longitudinales , Lactante , Estatura , Índice de Masa Corporal , Peso Corporal , Recién Nacido , Niño , Estudios de Casos y Controles , Fenilalanina/sangreRESUMEN
Phenylketonuria (PKU), caused by variants in the phenylalanine hydroxylase (PAH) gene, is the most common autosomal-recessive Mendelian phenotype of amino acid metabolism. We estimated that globally 0.45 million individuals have PKU, with global prevalence 1:23,930 live births (range 1:4,500 [Italy]-1:125,000 [Japan]). Comparing genotypes and metabolic phenotypes from 16,092 affected subjects revealed differences in disease severity in 51 countries from 17 world regions, with the global phenotype distribution of 62% classic PKU, 22% mild PKU, and 16% mild hyperphenylalaninemia. A gradient in genotype and phenotype distribution exists across Europe, from classic PKU in the east to mild PKU in the southwest and mild hyperphenylalaninemia in the south. The c.1241A>G (p.Tyr414Cys)-associated genotype can be traced from Northern to Western Europe, from Sweden via Norway, to Denmark, to the Netherlands. The frequency of classic PKU increases from Europe (56%) via Middle East (71%) to Australia (80%). Of 758 PAH variants, c.1222C>T (p.Arg408Trp) (22.2%), c.1066-11G>A (IVS10-11G>A) (6.4%), and c.782G>A (p.Arg261Gln) (5.5%) were most common and responsible for two prevalent genotypes: p.[Arg408Trp];[Arg408Trp] (11.4%) and c.[1066-11G>A];[1066-11G>A] (2.6%). Most genotypes (73%) were compound heterozygous, 27% were homozygous, and 55% of 3,659 different genotypes occurred in only a single individual. PAH variants were scored using an allelic phenotype value and correlated with pre-treatment blood phenylalanine concentrations (n = 6,115) and tetrahydrobiopterin loading test results (n = 4,381), enabling prediction of both a genotype-based phenotype (88%) and tetrahydrobiopterin responsiveness (83%). This study shows that large genotype databases enable accurate phenotype prediction, allowing appropriate targeting of therapies to optimize clinical outcome.
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Predisposición Genética a la Enfermedad/genética , Fenilcetonurias/epidemiología , Fenilcetonurias/genética , Alelos , Biopterinas/análogos & derivados , Biopterinas/genética , Europa (Continente) , Frecuencia de los Genes/genética , Estudios de Asociación Genética/métodos , Genotipo , Homocigoto , Humanos , Mutación/genética , Fenotipo , Fenilalanina/sangre , Fenilalanina Hidroxilasa/genética , Fenilcetonurias/sangreRESUMEN
BACKGROUND: Aging myocardium undergoes progressive cardiac hypertrophy and interstitial fibrosis with diastolic and systolic dysfunction. Recent metabolomics studies shed light on amino acids in aging. The present study aimed to dissect how aging leads to elevated plasma levels of the essential amino acid phenylalanine and how it may promote age-related cardiac dysfunction. METHODS: We studied cardiac structure and function, together with phenylalanine catabolism in wild-type (WT) and p21-/- mice (male; 2-24 months), with the latter known to be protected from cellular senescence. To explore phenylalanine's effects on cellular senescence and ectopic phenylalanine catabolism, we treated cardiomyocytes (primary adult rat or human AC-16) with phenylalanine. To establish a role for phenylalanine in driving cardiac aging, WT male mice were treated twice a day with phenylalanine (200 mg/kg) for a month. We also treated aged WT mice with tetrahydrobiopterin (10 mg/kg), the essential cofactor for the phenylalanine-degrading enzyme PAH (phenylalanine hydroxylase), or restricted dietary phenylalanine intake. The impact of senescence on hepatic phenylalanine catabolism was explored in vitro in AML12 hepatocytes treated with Nutlin3a (a p53 activator), with or without p21-targeting small interfering RNA or tetrahydrobiopterin, with quantification of PAH and tyrosine levels. RESULTS: Natural aging is associated with a progressive increase in plasma phenylalanine levels concomitant with cardiac dysfunction, whereas p21 deletion delayed these changes. Phenylalanine treatment induced premature cardiac deterioration in young WT mice, strikingly akin to that occurring with aging, while triggering cellular senescence, redox, and epigenetic changes. Pharmacological restoration of phenylalanine catabolism with tetrahydrobiopterin administration or dietary phenylalanine restriction abrogated the rise in plasma phenylalanine and reversed cardiac senescent alterations in aged WT mice. Observations from aged mice and human samples implicated age-related decline in hepatic phenylalanine catabolism as a key driver of elevated plasma phenylalanine levels and showed increased myocardial PAH-mediated phenylalanine catabolism, a novel signature of cardiac aging. CONCLUSIONS: Our findings establish a pathogenic role for increased phenylalanine levels in cardiac aging, linking plasma phenylalanine levels to cardiac senescence via dysregulated phenylalanine catabolism along a hepatic-cardiac axis. They highlight phenylalanine/PAH modulation as a potential therapeutic strategy for age-associated cardiac impairment.
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Envejecimiento/metabolismo , Miocardio/metabolismo , Fenilalanina/metabolismo , Envejecimiento/patología , Aminoácidos/metabolismo , Animales , Biomarcadores , Biopterinas/análogos & derivados , Biopterinas/farmacología , Catálisis , Senescencia Celular/efectos de los fármacos , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades , Cardiopatías/etiología , Cardiopatías/metabolismo , Cardiopatías/patología , Cardiopatías/fisiopatología , Humanos , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Ratones , Ratones Noqueados , Modelos Biológicos , Miocardio/patología , Miocitos Cardíacos/metabolismo , Fenilalanina/sangre , RatasRESUMEN
Pegvaliase (Palynziq®) is an enzyme substitution therapy using PEGylated recombinant Anabaena variabilis phenylalanine ammonia lyase (PAL) to reduce blood phenylalanine (Phe) levels in adults with phenylketonuria (PKU). In Phase 3 clinical studies, all subjects treated with pegvaliase developed anti-drug antibodies. To specifically evaluate pegvaliase-neutralizing antibodies (NAbs) and assess impact on pegvaliase efficacy, a novel hybrid ligand-binding/tandem mass spectrometry NAb assay was developed. Analysis of Phase 3 study samples revealed that pegvaliase NAb titers developed during early treatment (≤6 months after treatment initiation), and then plateaued and persisted in the majority of subjects during late treatment (>6 months). Subjects with the lowest/undetectable NAb titers had relatively high plasma pegvaliase concentrations and experienced the most rapid decline in blood Phe concentrations at relatively low pegvaliase dose concentrations. In contrast, subjects with higher NAb titers generally had lower plasma pegvaliase concentrations on similar low doses, with little change in blood Phe concentrations. However, with additional time on treatment and individualized dose titration, the majority of subjects achieved substantial and sustained blood Phe reduction, including those with higher NAb titers. Moreover, after maturation of the anti-pegvaliase immune response, NAb titers were stable over time and did not rise in response to dose increases; thus, subjects did not require additional dose increases to maintain reduction in blood Phe.
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Anticuerpos Neutralizantes/sangre , Fenilanina Amoníaco-Liasa/sangre , Fenilanina Amoníaco-Liasa/uso terapéutico , Adulto , Anticuerpos Neutralizantes/inmunología , Humanos , Fenilalanina/sangre , Fenilanina Amoníaco-Liasa/efectos adversos , Fenilanina Amoníaco-Liasa/inmunología , Fenilcetonurias/tratamiento farmacológico , Proteínas Recombinantes/efectos adversos , Proteínas Recombinantes/sangre , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/uso terapéuticoRESUMEN
Sapropterin dihydrochloride has been approved for the treatment of hyperphenylalaninemia in infants and young children with phenylketonuria (PKU). Sapropterin can reduce phenylalanine (Phe) levels in tetrahydrobiopterin (BH4)-responsive patients, potentially preventing the intellectual impairment caused by elevated Phe levels. The long-term effect of sapropterin on intellectual functioning was assessed using the Full-Scale Intelligence Quotient (FSIQ) in 62 children who began treatment before the age of 6 years. Over each 2-year interval, the estimate of mean change in FSIQ was -0.5768 with a lower limit of the 95% confidence interval (CI) of -1.60. At the end of the follow-up period (Year 7), the least squares mean estimate of the change in FSIQ from baseline was 1.14 with a lower limit of the 95% CI of -3.53. These lower limits were both within the clinically expected variation of 5 points. During the whole study period, mean blood Phe levels remained within the American College of Medical Genetics (ACMG) target range of 120-360 µmol/L. In addition, height, weight, and head circumference were maintained within normal ranges throughout follow-up, as defined by growth charts from the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) for children below and above the age of 24 months, respectively. All patients (n = 65) enrolled in this study experienced at least one adverse event, as expected from previous studies. In conclusion, long-term use of sapropterin in individuals with PKU helps to control blood Phe, preserve intellectual functioning, and maintain normal growth in BH4-responsive children who initiated treatment between the ages of 0 to 6 years.
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Biopterinas/análogos & derivados , Fenilalanina/sangre , Fenilcetonurias/tratamiento farmacológico , Fenilcetonurias/fisiopatología , Biopterinas/administración & dosificación , Niño , Preescolar , Femenino , Estudios de Seguimiento , Humanos , Lactante , Recién Nacido , Masculino , Personas con Discapacidades Mentales/rehabilitación , Fenilalanina/genética , Fenilcetonurias/sangreRESUMEN
Pegvaliase-pqpz (Palynziq) is an enzyme substitution therapy FDA approved May 2018 to treat phenylketonuria in adults with blood phenylalanine levels greater than 600 µmol/L (10 mg/dL). Pegvaliase is administered via subcutaneous injection and carries a high risk of side effects including anaphylaxis. A consensus statement on its use recommends careful education and monitoring of patients. We established a dedicated Palynziq Clinic in October 2018 with detailed protocols to minimize these risks. In the first year, we evaluated 43 patients, initiated Palynziq in 37 and transitioned two trial patients to commercial drug. 13/37 patients (35.1%) have sustained blood phenylalanine levels <360 µmol/L (6 mg/dL) without adjunct sapropterin dihydrochloride treatment or medical food. The timing and dosage needed to achieve a response did not correlate with patient weight, starting phenylalanine level, starting diet, or co-treatment with sapropterin dihydrochloride. Some patients had consistently low phenylalanine levels <30 µmol/L (0.5 mg/dL) and required doses as low as 20 mg weekly. Anaphylactic episodes were reported by 21.6% (8/37 patients) versus 10% seen in the clinical trial. Rates of other side effects were similar to or less than those in the trial. Adverse reactions commonly occurred shortly after dosage increases. We provide a model for safely introducing and managing pegvaliase in adult patients with PKU.
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Instituciones de Atención Ambulatoria/estadística & datos numéricos , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/prevención & control , Fenilanina Amoníaco-Liasa/uso terapéutico , Fenilcetonurias/tratamiento farmacológico , Adolescente , Adulto , Anafilaxia/etiología , Anafilaxia/prevención & control , Consenso , Femenino , Humanos , Masculino , Persona de Mediana Edad , Fenilalanina/sangre , Fenilanina Amoníaco-Liasa/administración & dosificación , Fenilanina Amoníaco-Liasa/efectos adversos , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/efectos adversos , Proteínas Recombinantes/uso terapéutico , Adulto JovenRESUMEN
BACKGROUND: Pegvaliase is an enzyme substitution therapy that reduces blood phenylalanine (Phe) in adults with phenylketonuria (PKU), and often allows normalization of protein intake (≥0.8 g protein/kg). Here we examine the nutrition status of adults with PKU consuming a normal protein intake without medical food after being treated with pegvaliase for ≥1 year. METHODS: A cross-sectional study evaluating nutritional intake (3-day food record and food frequency questionnaire), anthropometrics, laboratory indices of protein, micronutrient, and essential fatty acid (EFA) status, and questionnaires evaluating food neophobia and Epicurean eating pleasure. RESULTS: Participants (n = 18, 61% female) started pegvaliase 4.9 ± 2.1 years prior to enrollment and were aged 38.2 ± 8.8 years with a mean BMI of 29.2 ± 4.1 kg/m2. Participants consumed a mean of 73.2 ± 17.6 g protein/d (1.0 ± 0.3 g/kg/d). Eleven participants had low blood Phe (<30 µmol/L) with adequate protein intake and normal indices of protein status. Micronutrient and EFA concentrations were normal except for mildly low vitamin D (<30 ng/mL, n = 12). Intakes of sodium, saturated fat, and added sugars exceeded recommendations for healthy adults, though mean diet quality was comparable to a US adult reference population. Lower food neophobia scores correlated with an increased aesthetic appreciation of food. However, 53% of participants self-reported having moderate (n = 6) to high (n = 3) food neophobia. DISCUSSION: Participants treated with pegvaliase consumed an unrestricted diet with adequate dietary protein and, overall, had normal protein, micronutrient, and fatty acid status. Despite low blood Phe, protein nutriture was not compromised. While nutritional deficiencies were not identified, diet quality was suboptimal and some participants reported food neophobia. Nutrition education remains an important component of care as patients adapt to a normal diet.
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Dieta , Estado Nutricional/efectos de los fármacos , Fenilanina Amoníaco-Liasa/uso terapéutico , Fenilcetonurias/tratamiento farmacológico , Adulto , Estudios Transversales , Proteínas en la Dieta/administración & dosificación , Ácidos Grasos Esenciales , Femenino , Humanos , Masculino , Micronutrientes/sangre , Persona de Mediana Edad , Fenilalanina/sangre , Fenilcetonurias/fisiopatología , Proteínas Recombinantes/uso terapéutico , Encuestas y CuestionariosRESUMEN
PURPOSE: Phenylalanine hydroxylase deficiency, or phenylketonuria (PKU), is a rare autosomal recessive metabolic disorder. Early diagnosis via newborn screening (NBS) and initiation of treatment prevent the development of cognitive impairment and other co-morbidities. The purpose of this study is to describe the natural history of PKU in the United States, including prevalence of co-morbidities and predictors of outcomes. METHODS: We analyzed data from a self-report survey in the NBS-PKU Connect online registry. We describe the participants' nutrition management strategies, barriers to management, outcomes of bone disorders, skin, and psychological co-morbidities, and the use of special education or other special services. Predictors of outcomes were identified and assessed, including the impact of sex, age, age at diagnosis, blood phenylalanine concentration, use of sapropterin, use of medical food, adherence to prescribed diet, use of low protein modified foods, whether they had ever been off-diet, and use of tyrosine supplementation. RESULTS: The 219 respondents included individuals with PKU or hyperphenylalanemia (n = 78), or their caregivers (n = 141). Most (84.3%) started treatment before the age of two weeks. About one-third indicated that they had been off-diet at some point in their lives, and 81.4% reported that they currently adhered to their prescribed diet, with adherence to prescribed diet decreasing with age. Blood phenylalanine concentration was under the recommended threshold of 360 µmol/L for 68.5% of participants. One-quarter of respondents reported psychological co-morbidities, with anxiety and ADD/ADHD being the most common. The incidence of psychological co-morbidities increased with age and with ever having been off diet. Special education or other special services were more likely to be reported by individuals who were diagnosed after one week of age. Skin disorders such as acne and eczema were more common in females than males, and a minority of participants reported bone disorders. CONCLUSIONS: Despite recommendations to maintain blood phenylalanine concentrations in the therapeutic range throughout life, it is not uncommon for adults with PKU to discontinue dietary management of their disorder. Early diagnosis was associated with reduced need for special education or other special services, and continuous treatment was associated with decreased psychological co-morbidities.
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Fenilalanina/sangre , Fenilcetonurias/fisiopatología , Sistema de Registros , Adolescente , Adulto , Niño , Preescolar , Comorbilidad , Dieta , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Evaluación Nutricional , Fenilcetonurias/complicaciones , Fenilcetonurias/epidemiología , Sistema de Registros/estadística & datos numéricos , Estados Unidos/epidemiología , Adulto JovenRESUMEN
BACKGROUND: A subset of patients with phenylketonuria benefit from treatment with tetrahydrobiopterin (BH4), although there is no consensus on the definition of BH4 responsiveness. The aim of this study therefore was to gain insight into the definitions of long-term BH4 responsiveness being used around the world. METHODS: We performed a web-based survey targeting healthcare professionals involved in the treatment of PKU patients. Data were analysed according to geographical region (Europe, USA/Canada, other). RESULTS: We analysed 166 responses. Long-term BH4 responsiveness was commonly defined using natural protein tolerance (95.6%), improvement of metabolic control (73.5%) and increase in quality of life (48.2%). When a specific value for a reduction in phenylalanine concentrations was reported (n = 89), 30% and 20% were most frequently used as cut-off values (76% and 19% of respondents, respectively). When a specific relative increase in natural protein tolerance was used to define long-term BH4 responsiveness (n = 71), respondents most commonly reported cut-off values of 30% and 100% (28% of respondents in both cases). Respondents from USA/Canada (n = 50) generally used less strict cut-off values compared to Europe (n = 96). Furthermore, respondents working within the same center answered differently. CONCLUSION: The results of this study suggest a very heterogeneous situation on the topic of defining long-term BH4 responsiveness, not only at a worldwide level but also within centers. Developing a strong evidence- and consensus-based definition would improve the quality of BH4 treatment.
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Biopterinas/análogos & derivados , Fenilalanina/genética , Fenilcetonurias/tratamiento farmacológico , Biopterinas/efectos adversos , Biopterinas/uso terapéutico , Canadá/epidemiología , Europa (Continente)/epidemiología , Humanos , Fenilalanina/sangre , Fenilalanina Hidroxilasa/genética , Fenilcetonurias/sangre , Fenilcetonurias/epidemiología , Fenilcetonurias/patología , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND: In patients with phenylketonuria, stability of blood phenylalanine and tyrosine concentrations might influence brain chemistry and therefore patient outcome. This study prospectively investigated the effects of tetrahydrobiopterin (BH4), as a chaperone of phenylalanine hydroxylase on diurnal and day-to-day variations of blood phenylalanine and tyrosine concentrations. METHODS: Blood phenylalanine and tyrosine were measured in dried blood spots (DBS) four times daily for 2 days (fasting, before lunch, before dinner, evening) and once daily (fasting) for 6 days in a randomized cross-over design with a period with BH4 and a period without BH4. The sequence was randomized. Eleven proven BH4 responsive PKU patients participated, 5 of them used protein substitutes during BH4 treatment. Natural protein intake and protein substitute dosing was adjusted during the period without BH4 in order to keep DBS phenylalanine levels within target range. Patients filled out a 3-day food diary during both study periods. Variations of DBS phenylalanine and Tyr were expressed in standard deviations (SD) and coefficient of variation (CV). RESULTS: BH4 treatment did not significantly influence day-to-day phenylalanine and tyrosine variations nor diurnal phenylalanine variations, but decreased diurnal tyrosine variations (median SD 17.6 µmol/l, median CV 21.3%, p = 0.01) compared to diet only (median SD 34.2 µmol/l, median CV 43.2%). Consequently, during BH4 treatment diurnal phenylalanine/tyrosine ratio variation was smaller, while fasting tyrosine levels tended to be higher. CONCLUSION: BH4 did not impact phenylalanine variation but decreased diurnal tyrosine and phenylalanine/tyrosine ratio variations, possibly explained by less use of protein substitute and increased tyrosine synthesis.
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Biopterinas/análogos & derivados , Fenilalanina Hidroxilasa/genética , Fenilalanina/sangre , Fenilcetonurias/tratamiento farmacológico , Tirosina/sangre , Adulto , Biopterinas/efectos adversos , Biopterinas/farmacología , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Niño , Preescolar , Pruebas con Sangre Seca , Femenino , Humanos , Masculino , Fenilalanina Hidroxilasa/antagonistas & inhibidores , Fenilcetonurias/genética , Fenilcetonurias/patologíaRESUMEN
Neurotoxic effects caused by high phenylalanine (Phe) in patients with phenylketonuria (PKU) can be avoided through dietary treatment. However, achieving the recommended Phe levels has been a challenge. This study aimed to investigate factors associated with adherence to PKU treatment among patients followed at a medical genetics public service in southern Brazil. Twenty-nine patients (early diagnosed, n = 20; late-diagnosed, n = 9) with classical (n = 16) or mild PKU (n = 13) aged 6-34 years (16.4 ± 7.5) and 16 caregivers were included. Blood Phe levels were recorded, and assessment tools measuring barriers to treatment, IQ, knowledge about disease, treatment, and perceived adherence were collected. Classical PKU patients showed higher current blood Phe levels than mild PKU patients (U = 37.000, p = 0.003). Lifetime and childhood Phe levels were associated with recent metabolic control (τ = 0.76, p = 0.000; τ = 0.70, p = 0.000, respectively). The perception of barriers to treatment was associated with a higher blood Phe level (τ = 0.39, p = 0.003). Tolerance to Phe, metabolic control throughout childhood, and perceived difficulty in living with demands of treatment are important factors of greater vulnerability to poor adherence in PKU patients.