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Life is complicated when you don’t have the tools you need


Phenylketonuria (PKU) can impact peoples’ lives in hidden ways every day.

For people living with phenylketonuria, high phenylalanine levels can adversely impact their mood, concentration and mental health. 1, 2, 3 This is in addition to the wider emotional challenges associated with managing this complex, lifelong condition.4

On the surface, there is a clear route for diagnosing and managing phenylketonuria. However, phenylketonuria is a hidden illness with many facets that are not always physically obvious to others.

The Live Unlimited PKU campaign developed the ‘Beneath the Surface’ position paper and executive summary to explore the neurocognitive, psychosocial and mental health impact of phenylketonuria and how this affects those living with this condition.

‘Beneath the Surface’ Position Paper

‘Beneath the Surface’ Executive Summary

What are the findings of the ‘Beneath the Surface’ position paper?

The paper highlights that people living with phenylketonuria (PKU) can be impacted by their condition in the following ways:


People living with PKU are more likely to struggle with memory, strategy and problem-solving skills5

Work & Education

The neurocognitive impact of PKU means that people living with PKU are less likely to achieve their senior high school diploma6


A recent study found that over 4 in 10 adults living with PKU feel socially excluded as a result of their condition3

Mood and Fatigue

13% of PKU patients reported underlying mood swings and 25% additionally reported experiencing fatigue7

Mental Health

50% of adults living PKU reported experiencing symptoms of anxiety or depression3

Social Impact

People with PKU can experience social difficulties and emotional problems due to their PKU1

I usually have emotional instability when my phenylalanine (Phe) levels are high… I get more sensitive sometimes, I get more irritable. It really affects my emotions.”

-PKU Patient Turkey

What changes does the ‘Beneath the Surface’ position paper outline?

To support people living with phenylketonuria, the ‘Beneath the Surface’ position paper calls for the following changes:

1. Psychological and practical support

Healthcare service providers should tailor care models to provide psychosocial and practical support for all people living with PKU.

2. Tools to support conversations with clinicians

Policymakers, clinicians, and the patient community should collaborate to develop tools that allow patients to have meaningful discussions with clinicians on their concentration, mood and quality of life.

3. Individualised care for PKU patients

Policymakers, clinicians and the patient community should review current management guidelines to identify how individualised care plans can be designed to better support PKU patients.

4. Collaboration across the rare disease community

Organisations (such as patient advocacy groups) and clinicians working across the rare disease community should collaborate to encourage policymakers to prioritise rare diseases within the health system.

PKU has many shades. If we focus only on the medical side, we will lose the emotional part of the patient.”

-PKU Patient Italy


  1. PKU (2021). How PKU Affects the Brain. Available at: [Accessed April 2023]
  2. Gentille, J.K., Ten Hoedt A.E., Bosch, A.M (2010) Psychosocial aspects of PKU: Hidden disabilities – A review. Mol Genet Metab, 99 Suppl 1:S64-7. doi: 10.1016/j.ymgme.2009.10.183.
  3. Ford S, O’Driscoll M, MacDonald A (2018). Living with phenylketonuria: lessons from the PKU community. Mol Genet Metab Rep, 17: pp 57–63. 10.1016/j.ymgmr.2018.10.002
  4. Nunn, R (2017). “It’s not all in my head!” – The complex relationship between rare diseases and mental health problems. Orphanet journal of rare diseases, 12(29). Available at: [Accessed June 2021]
  5. Bartus, A., Palasti, F., Juhasz, E., et al. (2018) The influence of blood phenylalanine levels on neurocognitive function in adult PKU patients. Metabolic Brain Disease, 33, pp. 1609–1615 (2018)
  6. Mütze, U., Roth, A., Weigel, J.F.W., et al (2011). Transition of young adults with phenylketonuria from pediatric to adult care Mutze. J Inherit Metab Dis, 34(3), pp. 701-9. doi: 10.1007/s10545-011-9284-x. Epub 2011 Feb 9.
  7. Borghi, L., Moreschi, C., Toscano, A., et al (2020). The PKU & ME study: A qualitative exploration, through co-creative sessions, of attitudes and experience of the disease among adults with phenylketonuria in Italy. Mol Genet Metab Rep. 2020 Jun; 23: 100585. Published online doi: 10.1016/j.ymgmr.2020.100585