| Recruiting | AAV Gene Therapy Clinical Study in Adult Classic PKU (PHEdom) NCT06332807 | NGGT INC. | Phase 1 / Phase 2 |
| Recruiting | Effect of Large Neutral Amino Acids in Adults With Classical Phenylketonuria NCT06337864 | Rigshospitalet, Denmark | N/A |
| Recruiting | Development of Novel Psychological Assessment Tools and Anxiety Intervention for Phenylketonuria NCT06560736 | University of Missouri-Columbia | N/A |
| Recruiting | Walking Program in Fatty Liver Children With Phenylketonuria NCT06718842 | Cairo University | N/A |
| Recruiting | Safety and Efficacy Study of NGGT002 in cPKU Adult Subjects NCT06687733 | NGGT (Suzhou) Biotechnology Co., Ltd. | Phase 1 / Phase 2 |
| Completed | PheCheck Feasibility Study NCT05998109 | Lumos Diagnostics | — |
| Withdrawn | PKU Low Calorie Drink Study NCT04272736 | Nutricia UK Ltd | N/A |
| Terminated | Open-label, Randomized, 2-way Crossover, Monocentric, Controlled Study to Evaluate the Effect on Daily PHE Flu NCT05827536 | APR Applied Pharma Research s.a. | N/A |
| Unknown | Additional Dietary Large Neutral Amino Acids (LNAA) for Improved Symptoms in Adult Classical Phenylktonuria (P NCT05174559 | University of Southern California | N/A |
| Completed | Evaluation of Phe Fluctuation in PKU Pts Treated With PKU GOLIKE Versus Standard Amino Acid Protein Substitute NCT05487378 | APR Applied Pharma Research s.a. | N/A |
| Recruiting | Safety and Efficacy Study of NGGT002 in PKU Adult Subjects NCT06061614 | The First Affiliated Hospital of Bengbu Medical University | EARLY_Phase 1 |
| Active Not Recruiting | Evaluation of Low Phenylalanine Formulas NCT06332105 | Ajinomoto Co., Inc. | N/A |
| Completed | Amino Acid Kinetics of GMP-AA in Healthy Human Volunteers NCT05971563 | Birmingham Women's and Children's NHS Foundation Trust | N/A |
| Unknown | Life With Phenylketonuria. Adult Neurological Outcome of PCU Screened Patients From 1971 to 2002. NCT04433728 | University Hospital, Lille | — |
| Terminated | Safety and Efficacy of HMI-103 in Participants With Classical PKU Due to PAH Deficiency NCT05222178 | Homology Medicines, Inc | Phase 1 |
| Completed | Preliminary Study of Brain Effects of Palynziq-Related Changes in Phenylalanine in Individuals With PKU NCT05356377 | University of Missouri-Columbia | — |
| Completed | Evaluation of PKU Explore France NCT04898829 | Vitaflo International, Ltd | N/A |
| Terminated | Study to Evaluate the Effect on Nitrogen Retention of Two Different Posology Schemes of PKU GOLIKE PLUS 3-16 a NCT05229549 | APR Applied Pharma Research s.a. | N/A |
| Completed | The Effect of Nursing Empowerment Program NCT05497050 | Cukurova University | N/A |
| Completed | Evaluation of PKU Sphere Liquid NCT05096988 | Vitaflo International, Ltd | N/A |
| Recruiting | Metabolic Control and Patient Well-being in Phenylketonuria: do Guidelines Make a Difference? NCT05128149 | University Children's Hospital, Zurich | — |
| Not Yet Recruiting | Comparison of Atherogenic Risk Factors and Efficacy of Nutritional Treatment Among Adult Phenylketonuria Patie NCT04969809 | University Medical Centre Ljubljana | N/A |
| Completed | Evaluation of the Express Plus Range NCT05051657 | Vitaflo International, Ltd | N/A |
| Terminated | Natural History Clinical Study in Adult PKU NCT04768348 | Homology Medicines, Inc | — |
| Completed | Acceptability and Tolerance of a Ready-to-use Protein Substitute in Tablet Form for the Dietary Management of NCT04375592 | metaX Institut fuer Diatetik GmbH | — |
| Withdrawn | Safety, Tolerability, Pharmacodynamics and Pharmacokinetics of CDX 6114 in PKU Patients NCT04256655 | Société des Produits Nestlé (SPN) | Phase 1 |
| Completed | Remote Neurocognitive and Psychological Assessment in PKU NCT04943393 | University of Missouri-Columbia | — |
| Completed | Evaluation of PKU Sphere in Italy NCT04679467 | Vitaflo International, Ltd | N/A |
| Unknown | Early Dietary Treated Patients With Phenylketonuria Can Achieve Normal Growth and Mental Development. NCT04302194 | Assiut University | — |
| Terminated | Safety and Tolerability of RTX-134 in Adults With Phenylketonuria NCT04110496 | Rubius Therapeutics | Phase 1 |
| Terminated | Short-term Effects of Good Metabolic Control on Cognitive Function, Wellbeing, and Metabolic Parameters in Adu NCT04210206 | Klaus Parhofer | N/A |
| Completed | A Prospective Clinical Study of Phenylketonuria (PKU) NCT04452513 | BioMarin Pharmaceutical | — |
| Recruiting | Nutritional Impacts of Palynziq on Patients With Phenylketonuria (PKU) NCT04404530 | Emory University | — |
| Completed | Patient and Observer Reported Outcome Measurements in Inborn Errors of Metabolism NCT04248062 | University Children's Hospital, Zurich | — |
| Completed | Impact of Fruit and Vegetables in PKU NCT05249218 | Alex Pinto | N/A |
| Withdrawn | Compliance, Tolerance and Acceptability of a Tablet Protein Substitute for the Dietary Management of Phenylket NCT03333720 | Nutricia UK Ltd | N/A |
| Completed | Effects of Synergy on Nutrient Intake and Acceptability in Phenylketonuria (PKU) NCT03777826 | Nutricia Research | N/A |
| Terminated | Gene Therapy Clinical Study in Adult PKU NCT03952156 | Homology Medicines, Inc | Phase 1 / Phase 2 |
| Completed | The Effects of CGMP in Children and Adults With PKU NCT04076176 | Vitaflo International, Ltd | N/A |
| Completed | Nutrition Status of Adults With PKU Before and During Treatment With Pegvaliase NCT03856203 | Boston Children's Hospital | — |
| Unknown | A Study Into the Future Cardiovascular Disease (CVD) Risk of Phenylketonuria (PKU) Patients on a Low Phenylala NCT04251494 | Guy's and St Thomas' NHS Foundation Trust | — |
| Completed | Market Research - Acceptability Study for a New PKU Protein Substitute NCT04318509 | Dr. Schär AG / SPA | N/A |
| Completed | Nutrition Status of Adults Treated With Pegvaliase NCT03792451 | Boston Children's Hospital | — |
| Completed | Nutritional Status in Phenylketonuria NCT03820804 | Universidade do Porto | — |
| Completed | A 16 Week Study Evaluating the Introduction of a GMP Based Protein Substitute in Participants With PKU NCT03771391 | Vitaflo International, Ltd | N/A |
| Enrolling By Invitation | Early Check: Expanded Screening in Newborns NCT03655223 | RTI International | — |
| Completed | Market Research - Acceptability Trial for a New PKU Amino Acid Based Protein Substitute NCT04309331 | Dr. Schär AG / SPA | N/A |
| Completed | Evaluation of PKU Sphere NCT03419819 | Vitaflo International, Ltd | N/A |
| Completed | Evaluating the Efficacy of PKU Synergy in Patients Expressing Phenylketonuria or Hyperphenylalaninemia NCT03167697 | Nutricia UK Ltd | N/A |
| Completed | PKU Skin Stripping NCT04368624 | Children's Hospital Medical Center, Cincinnati | — |
| Completed | Testing of Four Home Phenylalanine Monitoring Prototype Devices NCT02445521 | Emory University | — |
| Completed | Bone Mineral Density in Adults With Hyperphenylalaninemia NCT01209819 | The University of Texas Health Science Center, Houston | — |
| Completed | Study of Phenoptin to Increase Phenylalanine Tolerance in Phenylketonuric Children on a Phenylalanine-restrict NCT00272792 | BioMarin Pharmaceutical | Phase 3 |
| Completed | A Phase 3, Multicenter, Open-Label Extension Study of Phenoptin in Subjects With PKU Who Have Elevated Phenyla NCT00225615 | BioMarin Pharmaceutical | Phase 3 |
| Completed | Study to Evaluate the Safety and Efficacy of Phenoptin™ in Subjects With Phenylketonuria Who Have Elevated Phe NCT00104247 | BioMarin Pharmaceutical | Phase 3 |
| Completed | Study to Evaluate the Response to and Safety of an 8-Day Course of Phenoptin™ Treatment in Subjects With Pheny NCT00104260 | BioMarin Pharmaceutical | Phase 2 |