Can untreated PKU patients escape from intellectual disability? A systematic review.

Danique van Vliet, Annemiek M J van Wegberg, Kirsten Ahring, Miroslaw Bik-Multanowski, Nenad Blau, Fatma D Bulut, Kari Casas, Bozena Didycz, Maja Djordjevic, Antonio Federico, François Feillet, Maria Gizewska, Gwendolyn Gramer, Jozef L Hertecant, Carla E M Hollak, Jens V Jørgensen, Daniela Karall, Yuval Landau, Vincenzo Leuzzi, Per Mathisen, Kathryn Moseley, Neslihan Ö Mungan, Francesca Nardecchia, Katrin Õunap, Kimberly K Powell, Radha Ramachandran, Frank Rutsch, Aria Setoodeh, Maja Stojiljkovic, Fritz K Trefz, Natalia Usurelu, Callum Wilson, Clara D van Karnebeek, William B Hanley, Francjan J van Spronsen

Journal: Orphanet journal of rare diseases 2019;13(1):149

PMID: 30157945

Abstract

BACKGROUND

Phenylketonuria (PKU) is often considered as the classical example of a genetic disorder in which severe symptoms can nowadays successfully be prevented by early diagnosis and treatment. In contrast, untreated or late-treated PKU is known to result in severe intellectual disability, seizures, and behavioral disturbances. Rarely, however, untreated or late-diagnosed PKU patients with high plasma phenylalanine concentrations have been reported to escape from intellectual disability. The present study aimed to review published cases of such PKU patients.

METHODS

To this purpose, we conducted a literature search in PubMed and EMBASE up to 8th of September 2017 to identify cases with 1) PKU diagnosis and start of treatment after 7 years of age; 2) untreated plasma phenylalanine concentrations ≥1200 μmol/l; and 3) IQ ≥80. Literature search, checking reference lists, selection of articles, and extraction of data were performed by two independent researchers.

RESULTS

In total, we identified 59 published cases of patients with late-diagnosed PKU and unexpected favorable outcome who met the inclusion criteria. Although all investigated patients had intellectual functioning within the normal range, at least 19 showed other neurological, psychological, and/or behavioral symptoms.

CONCLUSIONS

Based on the present findings, the classical symptomatology of untreated or late-treated PKU may need to be rewritten, not only in the sense that intellectual dysfunction is not obligatory, but also in the sense that intellectual functioning does not (re)present the full picture of brain damage due to high plasma phenylalanine concentrations. Further identification of such patients and additional analyses are necessary to better understand these differences between PKU patients.

Address: University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, 9700, RB, Groningen, The Netherlands.; University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, 9700, RB, Groningen, The Netherlands.; Department of Gastroenterology, Radboud University Medical Center, Nijmegen, The Netherlands.; Department of PKU, Kennedy Center, Copenhagen University Hospital, Glostrup, Denmark.; University Children's Hospital, Jagiellonian University, Krakow, Poland.; Dietmar-Hopp Metabolic Center, University Children's Hospital, Heidelberg, Germany.; Department of Pediatrics, Cukurova University Faculty of Medicine, Adana, Turkey.; Medical Genetics, Sanford Health, Fargo, ND, USA.; Mother and Child Health Care Institute of Serbia Dr Vukan Cupic, School of Medicine, University of Belgrade, Belgrade, Serbia.; Department of Medical, Surgical and Neurological Sciences, Medical School, University of Siena, Policlinico Santa Maria Alle Scotte, Siena, Italy.; Department of Pediatrics, Hôpital d'Enfants Brabois, CHU Nancy, Vandoeuvre les Nancy, France.; Department of Pediatrics, Endocrinology, Diabetology, Metabolic Diseases and Cardiology of the Developmental Age, Pomeranian Medical University, Szczecin, Poland.; Department of General Pediatrics, Division of Neuropediatrics and Metabolic Medicine, Center for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany.; Department of Pediatrics, Tawam Hospital, Al-Ain, United Arab Emirates.; Department of Internal Medicine, Division of Endocrinology and Metabolism, Academic Medical Center, Amsterdam, Netherlands.; Department of Pediatrics, Oslo University Hospital, Oslo, Norway.; Clinic for Pediatrics, Inherited Metabolic Disorders, Medical University of Innsbruck, Innsbruck, Austria.; Metabolic Disease Unit, Sheba Medical Center, Edmond and Lily Safra Children's Hospital, Tel Aviv, Israel.; Department of Pediatrics, Child Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy.; Department of Internal Medicine, Oslo University Hospital, Oslo, Norway.; Genetics Division, Department of Pediatrics, Keck School of Medicine, University of Southern California, California, Los Angeles, USA.; Department of Clinical Genetics, United Laboratories, Tartu University Hospital and Institute of Clinical Medicine, University of Tartu, Tartu, Estonia.; Department of Genetics and Metabolism, Chapel Hill hospital, University of North Carolina, Chapel Hill, USA.; Department of Chemical Pathology and Metabolic Medicine, Guys and St Thomas' Hospitals NHS foundation trust, London, UK.; Department of General Pediatrics, Muenster University Children's Hospital, Muenster, Germany.; Department of Pediatrics, Tehran University of Medical Sciences, Tehran, Iran.; Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia.; Institute of Mother and Child, Centre of Reproductive Health and Medical Genetics, Chisinau, Moldova.; Newborn Metabolic Screening Unit, LabPlus, Auckland City Hospital, Auckland, New Zealand.; Departments of Pediatrics and Clinical Genetics, Academic Medical Centre, Emma Children's Hospital, Amsterdam, The Netherlands.; Department of Pediatrics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada.; Clinical and Biochemical Genetics, Department of Pediatrics, The Hospital for Sick Children and the University of Toronto, Toronto, Canada.; University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, 9700, RB, Groningen, The Netherlands. [email protected].
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