patients with beta thalassemia major, requiring blood transfusion regimen. Additional blood sampling will be performed before and immediately after transfusion (21 millilters and 24 millilters respectively), on the occasion of 3 programed transfusions (consecutive or not).

Patients with beta thalassemia trait, matched with THAL + for age and gender. An unique blood sampling of 24 millilters will be performed.

healthy subjects, matched with THAL + for age and gender. An unique blood sampling of 24 millilters will be performed.

additional blood sampling for coagulation tests

Measurement of the area under the thrombin generation curve (ie ETP) in THAL+ patients, before and after transfusion, as compared with ETP measured in controls groups (THAL- and healthy volunteers)

Measurement of the area under the thrombin generation curve before and after transfusion in THAL+ patients over 3 transfusion episodes