A significantly higher proportion of patients with rare diseases (RD) with intellectual disability (ID), present hyperphagia, overweight or obesity, compared to the general population. Prader-Willi syndrome is the only genetic obesity identified to date associated with hyperghrelinemia, while ghrelin levels are lower than in controls in other situations of obesity.

The aim of the study is to find out whether the levels of ghrelin, which are abnormally high in PWS throughout life, are also high in these RD when people have hyperphagia and/or overweight.

A significantly higher proportion of patients with rare diseases (RD) with intellectual disability (ID), present hyperphagia, overweight or obesity, compared to the general population. Prader-Willi Syndrome (PWS) and related syndromes (PWS-like) represent the most well-known causes of eating disorders with early and severe obesity. Other known RD with ID have been described as being associated with eating disorders with overweight or obesity, which appear later in adolescence : Angelman's syndrome (approximately 40% of patients are overweight or obese, and 32% of children have hyperphagia), Fragile X syndrome (over 30% are obese), Smith-Magenis syndrome (50 to 60% are obese). Prader-Willi syndrome is the only genetic obesity identified to date associated with hyperghrelinemia, while ghrelin levels are lower than in controls in other situations of obesity.

The aim of the study is to find out whether the levels of ghrelin, which are abnormally high in PWS throughout life, are also high in these pathologies when people have hyperphagia and/or overweight.

The study involves a single visit carried out during a routine follow-up in the CRMR, in which the blood sample will allow the dosage of the ghrelin hormon. The visit will also involves a data collection and some questionnaires.

Inclusion Criteria:

• Patients with one of the following rare diseases associated with : Angelman syndrome, Smith-Magenis syndrome, X Fragile syndrome, rare diseases of the cerebellum, rare epilepsies, PW-like syndromes or other rare diseases with eating disorders
• Patients aged minimum 3 years and maximum 50 years.
• Patients with overweight (or obesity) and/or hyperphagic behavior.

Exclusion Criteria:

• Administrative problems: impossibility of giving parents or legal guardians informed information ; no coverage by a Social Security scheme.

patients infants and adults presenting a rare disease with overweight and hyperphagic behavior