The long term burden of morbidity and mortality in the natural history of sickle cell disease has not been compared up to date to the risks and mortality of a curative option like bone marrow transplantation in severe sickle-cell disease patients. Given this lack of data, primary-care Sickle Cell Disease (SCD) physicians and transplant physicians are prevented from a factual debate over the benefit/risk ratio for each patient and refining indications of transplant in patients. Therefore, the present study seeks to describe and compare the very long-term outcomes after either Human Leukocyte Antigen (HLA) -matched sibling transplantation (study arm) and "non-transplant care" for severe sickle cell disease SCA patients in order to yield robust comparative data regarding both arms.

The main objective is to assess the benefit of Hematopoietic stem cell transplantation (HSCT) regarding quality of life compared to standard care after 10 years, in patients with severe Sickle Cell Disease (SCD).

Inclusion Criteria:

Study population (exposed-patients), all criteria should be fulfilled:

1. Patients alive with Sickle Cell Anemia (SCA, meaning SS and Sbeta0 sickle cell anemia genotype)
2. Patients transplanted from allogeneic HLA-compatible sibling donor or from sibling cord blood unit from the 1st of January 2000 and the 31st of December 2012, whatever the age at transplant
3. Patients having received conditioning regimen containing busulfan 1mg/kg/dose (or equivalent adjusted body-weight dosage according to recommendation) x 16 doses + cyclophosphamide 200mg/kg total dose + anti-thymoglobuline
4. For patient under 18 years at time of enrolment, signed informed consent from both parental representatives
5. For patient aged 18 years old : signed informed consent
6. Having an affiliation to a social security regime

Control-population (Non-exposed patients) :

For each allografted patient, one non-exposed patient will be matched, based on the following criteria:

• Gender

• Age at the date of transplantation of the exposed patient (+/- 1 year)

• Foetal hemoglobin (HbF) level (+/- 3%) before treatment intensification (defined as the initiation of either hydroxyurea or a transfusion program)

• Hb level (+/- 0,9 g/dl) before treatment intensification

  1. For patient under 18 years at time of enrolment, signed informed consent from both parental representatives
  2. For patient above 18 years of age: signed informed consent
  3. Having an affiliation of to a social security regime

Exclusion Criteria:

Study population:

• Transplantation from donor other than sibling or related cord-blood
• Conditioning regimen other than busulfan 16mg/kg total dose + cyclophosphamide 200mg/kg total dose + anti-thymoglobuline

For both population:

• Absence of signed informed consent
• Having any debilitating medical or psychiatric illness, which preclude understanding of the inform consent as well as optimal treatment and follow-up