Acute splenic sequestration is a frequent and life threatening complication occurring in approximately 10 % of homozygous children. Maximal incidence is between 6 and 18 months.

The investigators formulate the hypothesis that there are clinical, biological and genetic markers predictive of severe complications notably acute splenic sequestration in SCD children. The present research project thus aims at analyzing in a forward-looking way the profile of severity by analysing clinical, biological and genetic characteristics in a multicentric cohort of 60 SCD children

A prospective multicentric analysis will be conducted in a cohort of 150 SS or S ß ° children diagnosed at birth, included at 3 -5 months and followed up to the age of 24 months.

Five visits, superimposed to the usual follow-up of SCD children, (Recommendations of the High Authority of Health) at 3 months, 6 months, 12 months, 18 months and 24 months will allow a clinical evaluation and an additional sampling of blood (5 mL) at each visit.

The samples will allow 1.analysis of the red blood cell phenotype (adhesion and deformability) and densities 2. the genetic profile 3.to establish a cell bank, a sera bank and a DNA bank, Spleen function in the cohort will be estimated by spleen scintigraphy, coupled with blood markers (pitted cells, Howell-Jolly bodies counts)

Inclusion criteria :

• Children aged 3 to 6 months
• homozygous (SS) or S beta° sickle cell disease diagnosed by neonatal screening
• With no history of acute splenic sequestration
• Signed parental consent
• Patient covered by national insurance scheme or CMU

Exclusion criteria :

• Children with other SCD genotype
• Children with congenital anatomical asplenia
• Children with previous episode of acute splenic sequestration
• Absence of possible follow-up
• Simultaneous enrolment in another biomedical research