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The lifelong impact of phenylketonuria is underrecognized1-3

High phenylalanine (Phe) levels can lead to serious phenylketonuria (PKU) symptoms4-6

Estimated prevalence ratios of diagnoses for patients with PKU compared with the general population table image
Estimated prevalence ratios of diagnoses for patients with PKU compared with the general population

Adapted from Bilder et al. Mol Genet Metab. 2017.

The effects of high Phe are felt throughout a patient’s life1

  • Controlling phenylalanine (Phe) levels in newborns and children prevents permanent intellectual disability1,6
  • However, adolescents and adults with uncontrolled Phe can experience neurologic, psychiatric, and cognitive symptoms, including:6
Depression and Anxiety Icons
Executive functioning and IQ icons

Mental and emotional stress of phenylketonuria (PKU)7

Even patients with blood Phe ≤500 µmol/L in childhood showed a higher frequency of a psychiatric diagnosis, such as

  • Generalized anxiety disorder
  • Depressive disorder
  • Personality disorder
  • Behavioral problems
  • Specific phobia
  • Selective mutism

Patients and their caregivers struggle with PKU symptoms8

I have blank moments where I can’t think or get my words out that I am trying to say. I experience anxiety and I get paranoid.”8

PKU Patient

I get “brain fog”, tend to become irritable and uneasy in social settings.”8

PKU Patient

When you can cause irreversible brain damage to your child, it causes a lot of worry, stress, and even panic.”8


The burden of PKU extends beyond the brain and into many aspects of adult life9

Adults with phenylketonuria (PKU) have an increased risk of several multisystemic comorbidities9

Adjusted prevalence ratio of comorbid conditions with patients PKU compared with non-PKU controls graph image
Adjusted prevalence ratio of comorbid conditions with patients PKU compared with non-PKU controls graph image

Adapted from Burton et al. Mol Genet Metab. 2018.

Patients with PKU struggle to maintain safe blood Phe levels10,11

  • A Phe-restricted diet is burdensome and provides inadequate protein intake
  • Phe control typically drops off during adolescence
  • By adulthood, most patients in the United States and Europe have Phe levels exceeding guideline recommendations

Learn more about PKU

Dietary control with PKU icon

Learn more about dietary control with PKU1

Above target Phe range icon

67% of adults with PKU are above guideline target Phe ranges11

PKU management options icon

Know your PKU management options

Stay connected with the latest PKU information

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  1. Vockley J, Andersson HC, Antshel KM, et al; American College of Medical Genetics and Genomics Therapeutic Committee. Phenylalanine hydroxylase deficiency: diagnosis and management guidelines. Genet Med. 2014;16(2):188-200.
  2. ten Hoedt AE, de Sonneville LMJ, Francois B, et al. High phenylalanine levels directly affect mood and sustained attention in adults with phenylketonuria: a randomised, double-blind, placebo-controlled, crossover trial. J Inherit Metab Dis. 2011;34(1):165-171.
  3. Trefz KF, Muntau AC, Kohlscheen KM, et al. Clinical burden of illness in patients with phenylketonuria (PKU) and associated comorbidities―a retrospective study of German health insurance claims data. Orphanet J Rare Dis. 2019;14(1):181. doi:10.1186/s13023-019-1153-y.
  4. Ashe K, Kelso W, Farrand S, et al. Psychiatric and cognitive aspects of phenylketonuria: the limitations of diet and promise of new treatments. Front Psychiatry. 2019;10:561. doi:10.3389/fpsyt.2019.00561
  5. Bilder DA, Kobori JA, Cohen-Pfeffer JL, Johnson EM, Jurecki ER, Grant ML. Neuropsychiatric comorbidities in adults with phenylketonuria: a retrospective cohort study. Mol Genet Metab. 2017;12(1):1-8.
  6. van Wegberg AMJ, MacDonald A, Ahring K, et al. The complete European guidelines of phenylketonuria: diagnosis and treatment. Orphanet J Rare Dis. 2017;12(1):162. doi: 10.1186/s13023-017-0685-2.
  7. Manti F, Nardecchia F, Chiarotti F, Carducci C, Leuzzi V. Psychiatric disorders in adolescent ad young adult patients with phenylketonuria. Mol Genet Metab. 2016;117(1):12-18.
  8. Ford S, O’Driscoll M, MacDonald A. Living with phenylketonuria: lessons from the PKU community. Mol Genet Metab Rep. 2018;17:57-63.
  9. Burton BK, Jones KB, Cederbaum S, et al. Prevalence of comorbid conditions among adult patients diagnosed with phenylketonuria. Mol Genet Metab. 2018;125(3):228-234.
  10. Brown CS, Lichter-Konecki U. Phenylketonuria (PKU): a problem solved? Mol Genet Metab Rep. 2016;6:8-12.
  11. Jurecki ER, Cederbaum S, Kopesky J, et al. Adherence to clinic recommendations among patients with phenylketonuria in the United States. Mol Genet Metab. 2017;120(3):190-197.
  12. van Spronsen FJ, van Wegberg AMJ, Ahring K, et al. Key European guidelines for the diagnosis and management of patients with phenylketonuria. Lancet Diabetes Endocrinol. 2017;5(9):743-756.
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