Immunopathology of Loeys-Dietz Syndrome

Inclusion Criteria: For patients with Loeys-Dietz syndrome: * Patients aged ≥ 5 years with Loeys-Dietz syndrome with a diagnosis confirmed by the presence of a TGF-βR 1 or R2 mutation known to be pathogenic to patients. * Free, informed and signed consent from the patient or both parents or legal guardians for minor patients. * Patient affiliated to a social security system or similar. For healthy volunteers: * Subjects aged ≥ 5 years. * Free, informed and signed consent of the witness, or if applicable of both parents or legal representatives for minors. * Patient affiliated to a social security system or similar. Exclusion Criteria: For patients with Loeys-Dietz syndrome: * Patient with an evolving or recently healed (\< 3 months) cancer that could alter the immunologic profile. * Patient with an evolving or recently healed (\< 3 months) infection that could alter the immunologic profile. * Patient with a weight of less than 20 kg. * Pregnant woman. * Patient participating in another research study with an exclusion period exclusion period still in progress. For healthy volunteers: * Subject with an active or recently cured (\< 3 months) cancer that could alter the immunologic profile. * Subject with an active or recently healed (\< 3 months) infection that could alter the immunological profile. * Patient with a weight of less than 20 kg. * Pregnant woman. * Subject participating in another research study with an exclusion period exclusion period still in progress. * Persons under court protection.