Sickle cell disease is caused by a mutation in the hemoglobin gene. The mutated hemoglobin contained in red blood cells (RBCs) can polymerize, causing a change in shape and functionality. This morphological change also leads to a stiffening of the RBCs, which can lead to vaso-occlusive crisis and serious organ damage. The deformability of RBC is therefore an important pathophysiological parameter in sickle cell disease. Most of the deformability analysis tools are population-based, so they are imperfectly adapted to the study of the different sub-populations simultaneously present in the blood of sickle cell patients. This project proposes to study the deformability properties of sickle cell RBCs, cell by cell, and will make it possible to quantify the number and the elongation of distinct GR subpopulations, potential prognostic markers during the follow-up of sickle cell patients treated by gene therapy.