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Impact Of A Phe-Restricted Diet On Gut Health In Children With PKU

21 juillet 2026 mis à jour par: Birmingham Women's and Children's NHS Foundation Trust

Impact Of A Phenylalanine-Restricted Diet On The Microbiota Composition And Metabolome Of Children With PKU

Phenylketonuria (PKU) is an inherited disorder of phenylalanine (Phe) metabolism. The mainstay of treatment is a Phe-restricted diet, which aims to maintain blood Phe concentrations within the recommended range and prevent neurological complications. Some individuals with PKU respond to pharmacological treatments, including sapropterin, a synthetic form of tetrahydrobiopterin (BH4), or sepiapterin. These treatments may increase Phe tolerance and allow a less restrictive diet.

Diet is an important determinant of gut microbiota composition and function. However, the effects of the Phe-restricted diet and pharmacologically enabled dietary relaxation on the gut microbiota in PKU remain poorly understood.

This observational study includes children and adolescents with PKU aged 3-17 years attending Birmingham Children's Hospital. Participants include those managed exclusively with a Phe-restricted diet, those receiving sapropterin, and those receiving sepiapterin. One healthy household control is recruited for each participant with PKU.

Faecal samples are collected for shotgun metagenomic sequencing and metabolite profiling. Dietary intake, gastrointestinal symptoms, stool characteristics, clinical information, and PKU treatment are also assessed.

The study investigates whether gut microbiota composition, microbial functional potential, and faecal metabolite profiles differ between participants managed with a Phe-restricted diet, those receiving pharmacological treatment, and healthy household controls. The findings may improve understanding of the relationships between PKU treatment, dietary restriction, gastrointestinal health, and the gut microbiome and may inform future nutritional strategies for individuals with PKU.

Aperçu de l'étude

Statut

Recrutement

Les conditions

Intervention / Traitement

Description détaillée

This is a single-centre, cross-sectional observational study conducted at Birmingham Children's Hospital. The study investigates the association between phenylketonuria (PKU) treatment, degree of dietary restriction, gastrointestinal health, and the composition and functional potential of the gut microbiota.

Children and adolescents aged 3-17 years with early-treated PKU are recruited into one of three cohorts according to their existing clinical management: treatment with a phenylalanine-restricted diet alone (anticipated n=30), treatment with sapropterin alongside an individualised phenylalanine-restricted diet (anticipated n=30), or treatment with sepiapterin alongside an individualised phenylalanine-restricted diet (anticipated n=14). Participants receiving sapropterin or sepiapterin have been receiving treatment for at least three months and have achieved at least a 100% increase in natural protein tolerance compared with their pre-treatment prescription. Treatment allocation, medication dosage, and dietary management are determined as part of routine clinical care and are not assigned or modified by the study.

One healthy household control is recruited for each participant with PKU. Household controls are aged 3 years or older and do not have PKU or another inherited metabolic disorder. Recruiting controls from the same household aims to reduce the influence of shared environmental factors, including living conditions and food availability, when comparing gut microbiota profiles. The anticipated total enrolment is 148 participants, comprising 74 participants with PKU and 74 household controls.

Each participant provides a single faecal sample. Samples are stored at -80°C and analysed using shotgun metagenomic sequencing to characterise microbial taxonomic composition, within-sample diversity, between-sample community differences, and microbial functional potential. Taxonomic profiles are assessed at multiple levels, including phylum, genus, and species. Functional annotation is used to characterise microbial genes, enzymes, and metabolic pathways.

Dietary intake is assessed using a 24-hour dietary recall, including natural protein intake, protein substitute intake, dietary fibre intake, and consumption of special low-protein foods. Gastrointestinal symptoms are assessed using the age-appropriate self-report or parent-proxy version of the PedsQL Gastrointestinal Symptoms Module, and stool form is assessed using the Bristol Stool Form Scale. Relevant demographic and clinical information, including age, sex, anthropometric measurements, PKU treatment, and metabolic control, is also collected.

The findings from this study may support the development of nutritional strategies and protein substitutes that more effectively promote gastrointestinal and metabolic health in individuals with PKU.

Type d'étude

Observationnel

Inscription (Estimé)

148

Contacts et emplacements

Cette section fournit les coordonnées de ceux qui mènent l'étude et des informations sur le lieu où cette étude est menée.

Coordonnées de l'étude

Sauvegarde des contacts de l'étude

Lieux d'étude

  • Royaume-Uni
    • Birmingham
      • Birmingham, Birmingham, Royaume-Uni, B4 6NH
        • Recrutement
        • Birmingham Children's Hospital
        • Contact:

Critères de participation

Les chercheurs recherchent des personnes qui correspondent à une certaine description, appelée critères d'éligibilité. Certains exemples de ces critères sont l'état de santé général d'une personne ou des traitements antérieurs.

Critère d'éligibilité

Âges éligibles pour étudier

  • Enfant

Accepte les volontaires sains

Oui

Méthode d'échantillonnage

Échantillon non probabiliste

Population étudiée

Children and adolescents aged 3-17 years with early-treated phenylketonuria receiving clinical care at Birmingham Children's Hospital are recruited into one of three cohorts according to their current treatment: a phenylalanine-restricted diet alone, sapropterin, or sepiapterin.

One healthy household control aged 3 years or older, without phenylketonuria or another inherited metabolic disorder, is recruited for each participant with phenylketonuria. All participants are enrolled according to predefined eligibility criteria.

La description

Inclusion Criteria:

Participants with PKU:

  • Aged 3-17 years.
  • Confirmed diagnosis of phenylketonuria following newborn screening.
  • Receiving ongoing clinical management for PKU.
  • For the diet-only cohort: managed with standard phenylalanine-restricted dietary treatment and not receiving sapropterin or sepiapterin.
  • For the sapropterin cohort: receiving sapropterin for at least three consecutive months and having achieved at least a 100% increase in natural protein tolerance compared with the pre-treatment prescription.
  • For the sepiapterin cohort: receiving sepiapterin for at least three consecutive months and having achieved at least a 100% increase in natural protein tolerance compared with the pre-treatment prescription.

Healthy household controls:

  • Aged 3 years or older.
  • Living in the same household as a participating child or adolescent with PKU.
  • No known diagnosis of PKU or another inherited metabolic disorder.

Exclusion Criteria:

  • Congenital malformations.
  • Chronic gastrointestinal disease.
  • Endocrine, liver, or kidney disease.
  • Other chronic medical conditions likely to affect gut microbiota composition.
  • Following a therapeutic diet for a medical condition other than PKU within the six months before stool sample collection.

Plan d'étude

Cette section fournit des détails sur le plan d'étude, y compris la façon dont l'étude est conçue et ce que l'étude mesure.

Comment l'étude est-elle conçue ?

Détails de conception

Cohortes et interventions

Groupe / Cohorte
Intervention / Traitement
PKU - Diet Only
Children and adolescents aged 3-17 years with early-treated phenylketonuria who are managed exclusively with a phenylalanine-restricted diet and are not receiving sapropterin or sepiapterin. Participants provide a faecal sample and undergo dietary, clinical, gastrointestinal symptom, and stool assessments.
Autre: Phenylalanine-restricted diet alone
Participants are managed with a phenylalanine-restricted diet and prescribed protein substitutes as part of their usual clinical care. They are not receiving sapropterin or sepiapterin. Dietary treatment is not assigned or modified by this observational study.
PKU - Sapropterin
Children and adolescents aged 3-17 years with early-treated phenylketonuria who have been receiving sapropterin for at least 3 months and have achieved at least a 100% increase in natural protein tolerance compared with before treatment. Sapropterin treatment is not assigned as part of this observational study. Participants provide a faecal sample and undergo dietary, clinical, gastrointestinal symptom, and stool assessments.
Médicament: Sapropterin Dihydrochloride
Participants receive sapropterin as part of their usual clinical care, alongside an individualised phenylalanine-restricted diet. Sapropterin treatment and dosage are prescribed independently of this observational study and are not assigned or modified by the investigators.
Autres noms:
  • Kuvan
PKU - Sepiapterin
Children and adolescents aged 3-17 years with early-treated phenylketonuria who have been receiving sepiapterin for at least 3 months and have achieved at least a 100% increase in natural protein tolerance compared with before treatment. Sepiapterin treatment is not assigned as part of this observational study. Participants provide a faecal sample and undergo dietary, clinical, gastrointestinal symptom, and stool assessments.
Médicament: Sepiapterin
Participants receive sepiapterin as part of their existing clinical management, alongside an individualised phenylalanine-restricted diet. Sepiapterin treatment and dosage are determined independently of this observational study and are not assigned or modified by the investigators.
Autres noms:
  • Séphiance
Healthy Household Controls
Healthy household members without phenylketonuria who are recruited at a ratio of one control for each participant with phenylketonuria. Controls provide a faecal sample and complete the relevant dietary, gastrointestinal symptom, and stool assessments.

Que mesure l'étude ?

Principaux critères de jugement

Mesure des résultats
Description de la mesure
Délai
Faecal gut microbiota taxonomic composition assessed by shotgun metagenomic sequencing
Délai: At enrolment (single faecal sample collection)
Taxonomic profiles, expressed as the relative abundance of microbial taxa at phylum, genus, and species levels, are derived from shotgun metagenomic sequencing of one faecal sample per participant. Profiles are compared among participants with PKU managed by a phenylalanine-restricted diet alone, sapropterin, or sepiapterin and healthy household controls.
At enrolment (single faecal sample collection)

Mesures de résultats secondaires

Mesure des résultats
Description de la mesure
Délai
Faecal gut microbiota alpha diversity assessed by shotgun metagenomic sequencing
Délai: At enrolment, based on a single faecal sample
Within-sample microbial diversity is assessed from shotgun metagenomic sequencing data using alpha-diversity indices, including Shannon, Simpson, Chao1, ACE, and observed species. Alpha-diversity measures are compared across the study cohorts.
At enrolment, based on a single faecal sample
Faecal gut microbiota beta diversity assessed by shotgun metagenomic sequencing
Délai: At enrolment, based on a single faecal sample
Differences in overall microbial community composition between participants are assessed using beta-diversity measures derived from shotgun metagenomic sequencing data, including Bray-Curtis dissimilarity. Microbial community profiles are compared across the study cohorts.
At enrolment, based on a single faecal sample
Microbial functional potential assessed by shotgun metagenomic sequencing
Délai: At enrolment, based on a single faecal sample
Microbial genes and functional pathways are characterised from shotgun metagenomic sequencing data using functional annotation databases. The relative abundance of microbial genes, enzymes, and metabolic pathways is compared across the study cohorts.
At enrolment, based on a single faecal sample
Gastrointestinal symptom burden assessed using the PedsQL Gastrointestinal Symptoms Module
Délai: At enrolment, based on a single faecal sample
Gastrointestinal symptoms are assessed using the age-appropriate self-report or parent-proxy version of the PedsQL Gastrointestinal Symptoms Module. Total and individual symptom-domain scores are calculated, with lower scores indicating a greater gastrointestinal symptom burden, and compared across the study cohorts.
At enrolment, based on a single faecal sample
Stool form assessed using the Bristol Stool Form Scale
Délai: At enrolment, based on a single faecal sample
Usual stool form is classified using the Bristol Stool Form Scale, ranging from type 1, representing separate hard lumps, to type 7, representing entirely liquid stool. Stool-form distributions are compared across the study cohorts.
At enrolment, based on a single faecal sample
Dietary intake assessed using a 24-hour dietary recall
Délai: At enrolment, based on a single faecal sample
Dietary intake is assessed using a 24-hour dietary recall. Nutrient and food-group measures, including natural protein intake, protein substitute intake, dietary fibre intake, and consumption of special low-protein foods, are estimated and compared across the study cohorts.
At enrolment, based on a single faecal sample

Collaborateurs et enquêteurs

C'est ici que vous trouverez les personnes et les organisations impliquées dans cette étude.

Parrainer

Birmingham Women's and Children's NHS Foundation Trust

Collaborateurs

Universidade Nova de Lisboa

Les enquêteurs

  • Chercheur principal: Anita MacDonald, PhD, Birmingham Children's Hospital

Dates d'enregistrement des études

Ces dates suivent la progression des dossiers d'étude et des soumissions de résultats sommaires à ClinicalTrials.gov. Les dossiers d'étude et les résultats rapportés sont examinés par la Bibliothèque nationale de médecine (NLM) pour s'assurer qu'ils répondent à des normes de contrôle de qualité spécifiques avant d'être publiés sur le site Web public.

Dates principales de l'étude

Début de l'étude (Réel)

1 octobre 2025

Achèvement primaire (Estimé)

1 décembre 2026

Achèvement de l'étude (Estimé)

1 décembre 2026

Dates d'inscription aux études

Première soumission

21 juillet 2026

Première soumission répondant aux critères de contrôle qualité

21 juillet 2026

Première publication (Réel)

27 juillet 2026

Mises à jour des dossiers d'étude

Dernière mise à jour publiée (Réel)

27 juillet 2026

Dernière mise à jour soumise répondant aux critères de contrôle qualité

21 juillet 2026

Dernière vérification

1 juillet 2026

Plus d'information

Termes liés à cette étude

Termes MeSH pertinents supplémentaires

Autres numéros d'identification d'étude

  • IRAS project ID: 353831

Plan pour les données individuelles des participants (IPD)

Prévoyez-vous de partager les données individuelles des participants (DPI) ?

NON

Description du régime IPD

There is no current plan to share individual participant data because the study involves a small population with a rare condition, which may increase the risk of participant identification. Any future data sharing would be subject to participant consent, ethical and institutional approvals, and an appropriate data-sharing agreement. Aggregated study results will be disseminated through scientific publications and presentations.

Informations sur les médicaments et les dispositifs, documents d'étude

Étudie un produit pharmaceutique réglementé par la FDA américaine

Non

Étudie un produit d'appareil réglementé par la FDA américaine

Non

Ces informations ont été extraites directement du site Web clinicaltrials.gov sans aucune modification. Si vous avez des demandes de modification, de suppression ou de mise à jour des détails de votre étude, veuillez contacter register@clinicaltrials.gov. Dès qu'un changement est mis en œuvre sur clinicaltrials.gov, il sera également mis à jour automatiquement sur notre site Web .

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