Sickle cell anemia

Sickle cell anemia is a severe chronic hemolytic anemia that occurs in individuals homozygous for the sickle gene, accompanied by a high mortality rate. Most often, this disease occurs in people of African descent. The frequency of sickle cell anemia is 1:625 newborns. Homozygotes do not synthesize HbA, their red blood cells contain 90-100% HbS.

Sickle cell hemoglobinopathies are widespread among residents of tropical Africa and in some areas of India, and are less common in the Mediterranean countries, the Near and Middle East, and America. Due to widespread population migration, they have recently begun to be encountered in Western Europe.

Sickle cell anemia is caused by homozygosity for Hb S or double heterozygosity: Hb S-β-thalassemia or Hb SC (Hb SE, Hb SD).

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Causes of Sickle Cell Anemia

The main defect in this pathology is the production of HbS as a result of a spontaneous mutation and deletion of the β-globin gene on chromosome 11, which leads to the replacement of valine with glutamic acid in the VIP position of the polypeptide chain (a ₂, β ₂, 6 val). Deoxygenation causes the deposition of deoxygenated molecules of abnormal hemoglobin in the form of monofilaments, which, as a result of aggregation, turn into crystals, thereby changing the membrane of erythrocytes, which, ultimately, is accompanied by the formation of sickle cells. It is believed that the presence of the sickle cell gene in the body gives the patient a certain degree of resistance to malaria.

Causes and pathogenesis of sickle cell anemia

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Symptoms of Sickle Cell Anemia

The disease occurs in the form of episodes of pain attacks (crises) associated with capillary occlusion as a result of spontaneous "crescentification" of erythrocytes, alternating with periods of remission. Crises can be provoked by intercurrent diseases, climatic conditions, stress, and spontaneous occurrence of crises is possible.

Clinical manifestations of the disease usually appear by the end of the first year of life. In newborns, fetal hemoglobin (HbF) predominates; as HbF decreases in the postnatal period, the concentration of HbS increases. Intravascular "crescents" and signs of hemolysis can be detected as early as 6-8 weeks of age, but clinical manifestations of the disease are usually not characteristic until 5-6 months of age.

Symptoms of Sickle Cell Anemia

Diagnosis of sickle cell anemia

The hemogram reveals normochromic hyperregenerative anemia - the hemoglobin concentration is usually 60~80 g / l, the number of reticulocytes is 50-150%. Peripheral blood smears usually contain erythrocytes that have undergone irreversible "sickle formation" - sickle-shaped erythrocytes; aniso- and poikilocytosis, polychromatophilia, ovalocytosis, micro- and macrocytosis are also detected, Cabot rings and Jolly bodies are found. The total number of leukocytes is increased to 12-20 x 10 ⁹ / l, neutrophilia is observed; the number of platelets is increased, the erythrocyte sedimentation rate is decreased.

Diagnosis of sickle cell anemia

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Treatment of sickle cell anemia

Transfusion therapy for sickle cell anemia is associated with increased blood viscosity until Hb S levels are significantly reduced; Ht should not exceed 25-30% before commencing red blood cell transfusion. Emergency blood transfusion is indicated only when there is a need to increase blood transport function without a significant reduction in Hb S levels, such as:

• in severe anemia;
• in case of sequestration crisis;
• during aplastic crisis;
• in case of blood loss;
• before surgery.

How is sickle cell anemia treated?