The present study will establish a collection of biological samples from Marfan patients or with associated diseases to be used for research purposes only, with due respect for confidentiality.

Marfan syndrome is an autosomal dominant disease (incidence 1/5000) characterized by ocular, cardiac and skeletal abnormalities. More recently, a decrease in fat and muscle mass has been demonstrated, associated with a decrease in exercise endurance, causing a significant deterioration in the quality of life. Little is known about the pathophysiology of these symptoms. Patients with Marfan syndrome or related diseases are followed at the children's hospital as part of the Rare Diseases Reference Centre (CRMR) for Marfan syndrome at the Toulouse University Hospital. During regular check-up visits, an extra sample of blood and urine will be collected and stored for research utilisation with the patient's consent. The ultimate objective of this collection is to provide available biological resources to facilitate the development of subsequent studies aimed at better characterizing the multisystemic disorders in Marfan syndrome, to understand the pathophysiology of the disease, and to identify biological factors that predict the severity and progression of the disease. The possibility of having systematically collected biological resources will make it possible to answer certain questions more quickly depending on the progress of research.

Inclusion Criteria:

• Children aged at least 3 years old or adult with Marfan syndrome or related syndromes
• Patients affiliated to or beneficiaries of a social security scheme
• Patients able to receive information on the progress of the study and understand the information form to participate in the study. That implies to master the French language and not to be subject to a restriction of rights by the judicial authorities
• Patients or legal representative who have given their consent to participate in the study (expression of no objection)

Exclusion Criteria:

• Patients subject to a legal protection measure (guardianship, curators, or safeguard of justice)
• Pregnant or breastfeeding women

Patients followed at the Rare Diseases Reference Centre (CRMR) for Marfan syndrome at the Toulouse University Hospital.