Ferroptosis Study in SF3B1-mutant Myelodysplastic Syndromes (FerMDS)

Inclusion Criteria: For all : * Patients of legal age (age ≥ 18 years) * Subjects affiliated to or benefiting from a social security scheme * Free, written and informed consent signed by the participant and the investigator For MDS patients : * Sampling at diagnosis for MDS patients (WHO 2016 criteria) * Presence of ring sideroblasts on bone marrow smear For MGUS patients : \- Sampling as part of the exploration of monoclonal gammopathy of undetermined significance (MGUS) for controls (WHO 2016 criteria). Exclusion Criteria: For all * Patient transfused with red blood cells within 120 days prior to collection * Patients treated with haematopoietic growth factors (EPO, TPO, G-CSF) within 30 days prior to collection * Patients with conditions that affect systemic iron metabolism: hemochromatosis, Gaucher disease, ferroportin disease, porphyria cutanea tarda * Person under a legal protection measure (legal protection, guardianship or curatorship) * Person deprived of liberty by judicial or administrative decision * Person who is unable to give consent * Subject who is in an exclusion period after another study or who has participated in another interventional drug study within 30 days prior to entry into the protocol