The sickle cell disease is a genetic disorder caused by an abnormality of hemoglobin ( Hb) , the mutation in cause having been inherited at the same time from the father and from the mother. Hemoglobinopathies, mainly thalassemia and sickle cell disease are observed worldwide .

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The sickle cell desease

1-1.The major sickle cell syndrome

They include various associations responsible for serious syndromes on the clinical and biological plan. We distinguish the homozygous shape SS (or sickle-cell anemia) and compound heterozygous forms connected to the association of the HbS in other hemoglobinopathy (HbS / HbC, HbS / ß thal, HbS / HbD-Punjab, or HbS / HbO-Arab)

1-2. THe mecanisms of the desease

Sickle cell disease is related to the presence of an abnormal hemoglobin in the red blood cell : hemoglobin S or HbS . In these patients, slowing the blood flow in the microvasculature allows , under certain conditions (dehydration, hypoxia, acidosis , ...), the polymerization of deoxygenated HbS . The polymerization of HbS causes deformation in sickles (sickling) and the stiffening of red blood cells.

The consequences are the obstruction of microvessels (vaso-occlusion) and premature destruction of red blood cells (hemolysis) . These two phenomena are at the origin of the cause of acute and chronic complications of the disease.

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Figure 1
Globules rouges normaux et globules rouges faucilles
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Figure 2
Gros plan.
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Figure 1
Globules rouges normaux et globules rouges faucilles

1-3. Clinical signs

Sickle cell disease is characterized by the possible occurrence as young as 3 months of acute complications of variable gravity, and the progressive installation of degenerative hurts and chronic complications. These can develop life-threatening and / or functional. The clinical expression of the disease evolves during the life of patients and is characterized by wide disparities from one patient to another.

Clinical features :

  • a chronic hemolytic anemia with potential consequences including the worsening of anemia or the occurrence of gallstones.
  • Increased susceptibility to infections by encapsulated bacteria (foreground the Pneumococcus and Salmonella ) due to a hyposplenism.
  • vaso- occlusive phenomena dominated by bone crises , and responsible lesions ( ischemic ) in the organs.
  • Infringements of the big vessels ( macrovessels) responsible cerebral stroke ; These hurts can be detected in children (transcranial Doppler , Nuclear Magnetic Resonance Imaging ) to set up a preventive therapeutics based on the realization of exchange transfusion protocols.

Source : Team of the Transversal Sickle Cell Unit of the University Hospital of Pointe-à-Pitre art . Mounlopital