| Not Yet Recruiting | Immune Modulation During Palynziq® Treatment in Adults (IMPALA) NCT07477691 | BioMarin Pharmaceutical | Phase 4 |
| Not Yet Recruiting | A Study to Evaluate Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of AG-181 in Subjects With Ph NCT07241234 | Agios Pharmaceuticals, Inc. | Phase 1 |
| Recruiting | A Study to Evaluate the Safety and Efficacy of JNT-517 in Participants With Phenylketonuria (PKU) NCT06971731 | Otsuka Pharmaceutical Development & Commercialization, Inc. | Phase 3 |
| Recruiting | Effect of Different Meal Types Given Before Exercise on Plasma Amino Acid Levels and Metabolic Control Paramet NCT07526909 | Hacettepe University | N/A |
| Recruiting | GMP Powdered Substitutes in PKU and TYR NCT06941532 | Nutricia UK Ltd | N/A |
| Active Not Recruiting | Rapid Drug Desensitization Study in Adults Experiencing Hypersensitivity Reactions to Palynziq NCT06780332 | BioMarin Pharmaceutical | Phase 4 |
| Active Not Recruiting | Effect of L-carnitine Supplementation on Phenylalanine and Brain-derived Neurotrophic Factor Levels in Infants NCT06901323 | Mansoura University | Phase 4 |
| Not Yet Recruiting | Announcement of Rare Metabolic Diseases in Systematic Newborn Screening: the Phenylketonuria Experience. NCT06289348 | Assistance Publique - Hôpitaux de Paris | — |
| Withdrawn | A Dose-finding Study to Evaluate mRNA-3210 in Participants With Phenylketonuria NCT06147856 | ModernaTX, Inc. | Phase 1 / Phase 2 |
| Recruiting | A Study of Sepiapterin in Participants With Phenylketonuria (PKU) NCT06302348 | PTC Therapeutics | Phase 3 |
| Unknown | Evaluation of Capillary Blood Collection Devices (Mitra® and HemaPEN®) NCT05894122 | University Hospital, Grenoble | — |
| Completed | Efficacy and Safety of Orally Administered Engineered Probiotics (CBT102-A) for the Treatment of Children With NCT05948020 | Children's Hospital of Fudan University | EARLY_Phase 1 |
| Active Not Recruiting | A Phase 1/Phase 2 Open-label Study to Evaluate the Safety, Tolerability, and Efficacy of a Single Intravenous NCT05972629 | Sanofi | Phase 1 / Phase 2 |
| Terminated | Efficacy and Safety of SYNB1934 in Patients With PKU (SYNPHENY-3) NCT05764239 | Synlogic | Phase 3 |
| Active Not Recruiting | First-in-Human, Multiple Part Clinical Study of JNT-517 in Healthy Participants and in Participants With Pheny NCT05781399 | Otsuka Pharmaceutical Development & Commercialization, Inc. | Phase 1 / Phase 2 |
| Terminated | Safety and Efficacy of HMI-103 in Participants With Classical PKU Due to PAH Deficiency NCT05222178 | Homology Medicines, Inc | Phase 1 |
| Active Not Recruiting | A Long-Term Safety Study of PTC923 in Participants With Phenylketonuria NCT05166161 | PTC Therapeutics | Phase 3 |
| Completed | A Study of PTC923 in Participants With Phenylketonuria NCT05099640 | PTC Therapeutics | Phase 3 |
| Completed | Study of Low-grade Systemic Inflammation in Adult Patients With Phenylketonuria NCT04879277 | University Hospital, Tours | N/A |
| Completed | Efficacy and Safety of SYNB1618 and SYNB1934 in Adult Patients With Phenylketonuria NCT04534842 | Synlogic | Phase 2 |
| Enrolling By Invitation | Long-Term Follow Up Study of Subjects Previously Administered HMI 102 NCT04348708 | Homology Medicines, Inc | — |
| Completed | Phenylalanine and Its Impact on Cognition NCT03788343 | Insel Gruppe AG, University Hospital Bern | Phase 4 |
| Completed | Protein Requirements in Adults With Phenylketonuria (PKU) NCT03939052 | University of British Columbia | N/A |
| Completed | Pharmacodynamics, Safety, Tolerability and Pharmacokinetics of CDX-6114 in Patients With Phenylketonuria (PKU) NCT04085666 | Société des Produits Nestlé (SPN) | Phase 1 |
| Completed | SNAP: Study Nutrients in Adult PKU NCT03858101 | Nutricia Research | — |
| Completed | Safety and Tolerability of SYNB1618 in Healthy Adult Volunteers and Adult Subjects With Phenylketonuria NCT03516487 | Synlogic | Phase 1 / Phase 2 |
| Completed | The Effectiveness of Kuvan in Amish PKU Patients NCT02677870 | University Hospitals Cleveland Medical Center | Phase 4 |
| Completed | MRI Spectroscopy and Neuropsychological Functioning in Phenylketonuria NCT03097250 | Boston Children's Hospital | — |
| Completed | Evaluation of PKU Explore NCT03168399 | Vitaflo International, Ltd | N/A |
| Completed | Evaluation of PKU Start NCT03058848 | Vitaflo International, Ltd | N/A |
| Completed | GMP Drink for PKU Study NCT02915510 | Nutricia UK Ltd | N/A |
| Completed | Simplified Diet Approach in Phenylketonuria NCT02555579 | University of Nebraska | N/A |
| Completed | A Phase 3 Substudy to Evaluate Executive Function in Adults With PKU Who Are Participating in the Phase 3 Stud NCT02468570 | BioMarin Pharmaceutical | — |
| Completed | The Brain and Neuropsychological Functioning in Adults With Sapropterin Dihydrochloride Treated Phenylketonuri NCT02297347 | Boston Children's Hospital | — |
| Completed | Observational Study of Endothelial Dysfunction in Phenylketonuria NCT02176603 | Charite University, Berlin, Germany | — |
| Terminated | Sapropterin on Cognitive Abilities in Young Adults With Phenylketonuria NCT01977820 | BioMarin Pharmaceutical | Phase 2 |
| Completed | Protein Requirements in Children With Phenylketonuria (PKU) NCT01965691 | University of British Columbia | N/A |
| Completed | Kuvan®'s Effect on the Cognition of Children With Phenylketonuria NCT01965912 | BioMarin Pharmaceutical | Phase 4 |
| Completed | Neurocognitive Outcomes in Mild Hyperphenylalaninemia (MHP)MHP Study NCT01924026 | The Hospital for Sick Children | — |
| Completed | The Brain, Neurological Features and Neuropsychological Functioning in Adults With Phenylketonuria: A Pilot St NCT01917344 | Boston Children's Hospital | N/A |
| Completed | Biological Variation of Phenylalanine in Patients With Hyperphenylalaninemia NCT01869972 | Hamilton Health Sciences Corporation | — |
| Completed | An Open-Label Phase 3 Study of BMN 165 for Adults With PKU Not Previously Treated w/ BMN 165 NCT01819727 | BioMarin Pharmaceutical | Phase 3 |
| Terminated | Moderate Intensity Exercise and Phenylketonuria NCT01904708 | Oregon Health and Science University | N/A |
| Completed | Phase 3 Open-label Study to Evaluate the Response and Safety of Kuvan® in Subjects With Phenylketonuria NCT01732471 | Merck KGaA, Darmstadt, Germany | Phase 3 |
| Completed | A Study to Evaluate Subcutaneously Administered rAvPAL-PEG in Patients With Phenylketonuria for 24 Weeks NCT01560286 | BioMarin Pharmaceutical | Phase 2 |
| Terminated | Liver Cell Transplant for Phenylketonuria NCT01465100 | Ira Fox | Phase 1 / Phase 2 |
| Completed | Phase 2 Study of Glycomacropeptide Versus Amino Acid Diet for Management of Phenylketonuria NCT01428258 | University of Wisconsin, Madison | N/A |
| Completed | Kuvan® in Phenylketonuria Patients Less Than 4 Years Old NCT01376908 | BioMarin Pharmaceutical | Phase 3 |
| Terminated | Phenylketonuria, Oxidative Stress, and BH4 NCT01395394 | Emory University | Phase 2 |
| Terminated | Bone Mineral Density in Adults With Hyperphenylalaninemia on Kuvan Therapy NCT01541397 | The University of Texas Health Science Center, Houston | N/A |
| Completed | Safety, Tolerability, and Efficacy Study of rAvPAL-PEG Administered Daily in Subjects With Phenylketonuria (PK NCT01212744 | BioMarin Pharmaceutical | Phase 2 |
| Completed | Evaluation of Behavior, Executive Function, Neurotransmitter Function and Genomic Expression Kuvan Nonresponde NCT01274026 | Tulane University School of Medicine | — |
| Completed | Safety and Therapeutic Effects of Sapropterin Dihydrochloride on Neuropsychiatric Symptoms in Phenylketonuria NCT01114737 | BioMarin Pharmaceutical | Phase 3 |
| Completed | Response to Kuvan® in Subjects With Phenylketonuria (PKU) in a 4 Weeks Testing Period NCT01082328 | Merck KGaA, Darmstadt, Germany | Phase 4 |
| Completed | Fluorodeoxyglucose Positron Emission Tomography (FDG PET) Findings in Patients With Phenylketonuria Before and NCT00986973 | Children's Hospital of Philadelphia | N/A |
| Completed | Follow-up of Adult Phenylketonuria (PKU) Patients NCT01096758 | Ludwig-Maximilians - University of Munich | — |
| Completed | Long-Term Extension of Previous rAvPAL-PEG Protocols in Subjects With PKU (PAL-003) NCT00924703 | BioMarin Pharmaceutical | Phase 2 |
| Completed | Dose-Finding Study to Evaluate the Safety, Efficacy, & Tolerability of Multiple Doses of rAvPAL-PEG in Subject NCT00925054 | BioMarin Pharmaceutical | Phase 2 |
| Completed | The Effects of Kuvan on Functional Brain Connectivity in Individuals With Phenylketonuria (PKU) NCT00964236 | University of Missouri-Columbia | — |
| Completed | Quantitative Requirements of Docosahexaenoic Acid for Neural Function in Children With Phenylketonuria NCT00909012 | Ludwig-Maximilians - University of Munich | N/A |
| Completed | Effect of Kuvan on Neurocognitive Function, Blood Phenylalanine Level, Safety, and Pharmacokinetics in Childre NCT00838435 | BioMarin Pharmaceutical | Phase 3 |
| Terminated | Behavioral Effects of Kuvan in Children With Mild Phenylketonuria NCT00827762 | Washington University School of Medicine | — |
| Completed | Kuvan Therapy in Phenylketonuria (PKU): The Effect of Blood Phenylalanine Concentration on Kuvan Response NCT00841100 | University of Miami | Phase 2 |
| Completed | Nutritional and Neurotransmitter Changes in PKU Subjects on BH4 NCT00688844 | Emory University | — |
| Completed | A Phase 1 Study to Evaluate Effects of Sapropterin Dihydrochloride on QTc Intervals in Healthy Adult Subjects NCT00789568 | BioMarin Pharmaceutical | Phase 1 |
| Completed | PKUDOS: Phenylketonuria (PKU) Demographic, Outcomes, and Safety Registry NCT00778206 | BioMarin Pharmaceutical | — |
| Completed | Study to Evaluate the Effects of Kuvan on Individuals With Phenylketonuria (PKU) With Maladaptive Behaviors NCT00728676 | Shoji Yano | — |
| Completed | Sapropterin in Individuals With Phenylketonuria NCT00730080 | Washington University School of Medicine | — |
| Completed | Safety and Tolerability Study of rAvPAL-PEG to Treat Phenylketonuria NCT00634660 | BioMarin Pharmaceutical | Phase 1 |
| Completed | The Effect of Supplemental Docosahexaenoic Acid (DHA) on Neurocognitive Outcomes in Teen and Adult Women With NCT00892554 | Emory University | N/A |
| Completed | Study of Phenoptin in Subjects With Phenylketonuria Who Participated in Protocols PKU-004 or PKU-006 NCT00332189 | BioMarin Pharmaceutical | Phase 3 |
| Completed | The Early History of Universal Screening for Metabolic Disorders NCT00309400 | University of Miami | — |
| Terminated | Response to Phenylketonuria to Tetrahydrobiopterin (BH4) NCT00244218 | The University of Texas Medical Branch, Galveston | Phase 1 |
| Completed | Study of BH4, a New and Simple Treatment of Mild PKU NCT00260000 | The Kennedy Institute-National Eye Clinic | Phase 2 |
| Recruiting | Educational, Social Support, and Nutritional Interventions and Their Cumulative Effect on Pregnancy Outcomes a NCT01659749 | Emory University | N/A |
| Completed | Low Phenylalanine Diet for Mothers With Phenylketonuria (PKU) NCT00065299 | Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) | N/A |
| Completed | Study of a Phenylalanine Restricted Diet During Pregnancy to Prevent Symptoms in Offspring of Patients With Ph NCT00006142 | National Center for Research Resources (NCRR) | N/A |
| Approved For Marketing | Sapropterin Expanded Access Program NCT00484991 | BioMarin Pharmaceutical | — |