SNAP: Study Nutrients in Adult PKU

Study Overview
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Brief Summary
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Phenylketonuria (PKU) is a rare inherited metabolic disorder, where subjects are born with a genetic deficiency in the phenylalanine hydroxylase enzyme (PAH), which leaves them unable to convert Phenylalanine (Phe) into Tyrosine (Tyr). PKU patients have specific dietary needs and must follow a restrictive diet in the aim of preventing toxic levels of the amino acid phenylalanine (Phe) accumulation.

Detailed Description
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The aim of this explorative cross-sectional study is to gain quantitative insights on blood nutrient levels of adult PKU patients on a protein substitute.

Official Title
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An Exploratory Matched Case-control Study to Measure Blood Nutrient Levels of Adult PKU Patients on a Protein Substitute.

Conditions
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Phenylketonuria

Participation Criteria
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Eligibility Criteria
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- Inclusion Criteria: Both PKU and Non-PKU comparison subjects: Age ≥18 years Willing and able to provide signed informed consent PKU specific inclusion criteria PKU patients identified by newborn screening and started low Phe diet before 1 month age Usage of at least one Phe-free protein substitute (i.e. an amino acid mixture including micronutrients) on a daily basis for at least 26 consecutive weeks up to Visit 1 Non-PKU comparison subjects specific inclusion criteria: Same age- (±3 years) and sex as an included PKU subject Exclusion Criteria: Both PKU and Non-PKU comparison subjects: For women: Currently pregnant or lactating Current psychiatric disorders Current Substance Use Disorders (as described in DSM V) Current use of psychotropic and/or inotropic medication Omega-3, antioxidant, (multi)vitamin and/or (multi)mineral supplement use within six weeks prior to entry in the study Severe hepatic, thyroid or renal dysfunction No acute illnesses like flu, diarrhea, or vomiting (subjects should be symptom free for a week prior to V1) Participation in any other clinical intervention studies involving test products concomitantly or within six weeks prior to entry into the study Other family members taking part in this study PKU subject specific exclusion criteria: Use of BH4, or drugs that may interfere with main outcomes Non-PKU comparison subjects specific exclusion criteria: Any condition or special diet (e.g. vegan or vegetarian diet) that effects the metabolism and/or normal dietary pattern/intake A first or second degree relative with inborn errors of metabolism Living together with someone with inborn errors of metabolism (e.g. partner, spouse or roommate)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| PKU subjects<br> | |
| Age and sex-matched non-PKU comparison subjects<br> | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood nutritional status | Micro-and macronutrients and amino acid levels [in a.o. mg/L] | day 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood nutritional status | Phe/Tyr ratio [µmol/L] | day 1 | 
| Nutrient intake | measured by three-day food diary. Nutrients in [mg/day] | day 1 - day 7 | 
| Subjective cognitive well-being | measured by FACT-Cog questionnaire: [four domains [score-range): 1) patients' perceived cognitive impairments [0-80]; 2) perceived cognitive abilities [0-36]; 3) noticeability or comments from others [0-16]; 4) impact of cognitive changes on quality of life [0-16]. A summary score is obtained by summing all item scores [0-148]. | day 1 - day 7 |