Background : Patients with hereditary spherocytosis (HS) are characterized by increased red blood cell (RBC) fragility and a loss of RBC deformability. While the clinical variability of the disease may be heterogenous from one patient to another, some studies reported the occurrence of vascular complications, notably in patients who have been splenectomized.

Purpose : The aim of the study is to test the associations between the degree of vascular dysfunction and the extent of hemolysis, the amount of circulating microparticles, the level of erythrosis and the degree of RBC biophysical alterations.

Abstract : Recent studies reported the occurrence of vascular complications in patients with HS, notably in patients who have previously been splenectomized. However, the exact reasons of these complications are unknown and no study investigated the vascular function in HS patients.

Main objective Highlight the presence of altered vascular function in HS patients and test the relationships with the level of hemolysis and circulating microparticles.

Secondary objectives To evaluate the associations between clinical severity and 1) the level of vascular dysfunction and 2) several biomarkers (hemolysis, hematological parameters, circulating microparticles, erythrosis, RBC biophysical properties).

Inclusion Criteria:

Healthy controls:

• age ≥ 6 years old
• written, informed and signed consent by the healthy volunteer, or by both parents or legal guardian if the healthy volunteer is a minor
• Healthy volunteer affiliated to a social security scheme or assimilated
• Healthy volunteer not subject to any legal protection measure

Patients with hereditary spherocytosis:

• age ≥ 6 years old
• Patient with hereditary or non-splenectomized spherocytosis
• Written, informed and signed consent by the patient, or by at least one of the two parents or legal guardian if the patient is a minor
• Patient affiliated to a social security scheme or assimilated
• Patient not subject to any legal protection measure

Exclusion Criteria:

Healthy controls:

• Pregnant or lactating woman
• Subjects with hereditary spherocytosis or other characterized condition by chronic hemolysis
• Subjects with known pathology affecting the vascular system
• Blood donation (less than a month old)
• Not affiliated to a social security scheme
• Patient participating in another interventional research protocol that may interfere with this protocol (according to the investigator's judgment).

Patients with hereditary spherocytosis:

• Patient who received a blood transfusion in the 3 months preceding
• Pregnant or lactating woman
• Any disease or condition other than hereditary spherocytosis, chronic or not, likely to induce chronic or acute intravascular hemolysis
• Patient participating in another interventional research protocol that may interfere with this protocol (according to the investigator's judgment).