Prader-Willi Syndrome Macronutrient Study

Study Overview
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Brief Summary
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The overall objective is to explore the mechanisms by which macronutrients regulate food intake and weight gain in Prader Willi Syndrome (PWS). Previous studies from the investigators' labs suggest that the increased appetite of PWS may be triggered or maintained by an increase in the levels of ghrelin, an appetite-stimulating hormone produced primarily by the stomach. This study will compare the effects of low carbohydrate diet versus low fat diet on levels of ghrelin, appetite suppressing hormones and markers of insulin sensitivity in patients with PWS. The investigators hypothesize that the low carbohydrate diet will suppress plasma active ghrelin and increase appetite-suppressing hormones to a greater degree and for longer duration than the low fat diet and will thereby reduce hyperphagia and increase satiety. The investigators also hypothesize that the low carb diet will improve hormonal and metabolic markers (fatty acids, amino acids and organic acids) of insulin sensitivity and inflammatory cytokine profiles of children with PWS.

Official Title
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Evidence-Based Approach to Dietary Management of Prader-Willi Syndrome (PWS)

Conditions
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Prader Willi Syndrome, Syndromic Obesity, Childhood Obesity

Intervention / Treatment
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* Other: Low Carbohydrate diet
* Other: Low Fat diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: diagnosis of Prader Willi syndrome confirmed by chromosome analysis (ie. interstitial deletion of paternally-derived chromosome 15q, uniparental maternal disomy or other chromosome 15 abnormalities) age 5 years to 17 years written informed consent and assent obtained and willingness to comply with the study schedule and procedures free T4, TSH values in the normal range (either endogenous or with thyroxine replacement) weight stable (BMI percentile fluctuation of <5 percentiles) over the preceding 2 months prior to the study Exclusion Criteria: presence of other clinically significant disease that would impact body composition including diabetes mellitus, chronic inflammatory bowel disease, chronic severe liver or kidney disease or neurologic disorders concomitant use of medications known to affect body weight or investigational drug in the past year

Ages Eligible for Study
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Minimum Age: 5 Years
Maximum Age: 17 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Low carbohydrate diet<br>Low carbohydrate diet: 15%carb; 65%fat; 20% protein. This will be administered over 72 hour hospital stay. | Other: Low Fat diet<br>* Low Fat diet: 65%carb; 15%fat; 20% protein<br>|
| Other: Low Fat diet<br>Low fat diet: 65%carb; 15%fat; 20% protein. This will be administered over a 72 hour hospital stay. | Other: Low Carbohydrate diet<br>* Low carbohydrate diet: 15%carb; 65%fat; 20% protein<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Suppression of ghrelin | Fasting labs will be obtained immediately following dietary intervention. These labs will include total and active ghrelin. | 10 hour fast following completion of dietary intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in satiety | Changes in subjective hunger will be assessed by an appetite and hyperphagia questionnaire validated for PWS children. This will be completed by the children, with assistance of their parents, at completion of the 72 hour dietary intervention. | During the 72 hour dietary intervention | 
| Improvements in insulin sensitivity | The analysis will include measurements of adiponectin, GLP-1, glucose, insulin, AST, ALT, insulin sensitivity and a detailed profile (metabolomics) of amino acids, fatty acids, acylcarnitines, and adipocytokines on the day prior to and immediately following dietary intervention. | During the 72 hour dietary intervention. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Prader Willi syndrome, childhood obesity, ghrelin, appetite regulation