Sickle cell anemia is an autosomal recessive condition that belongs to hemolytic anemias or hemoglobinopathies. It is triggered by a point mutation of the β-chain of hemoglobin, which results in the formation of irregular hemoglobin, the so-called sickle cell hemoglobin (HbS). One distinguishes a severe, homozygous form from a mild, heterozygous form. In the deoxygenated state of HbS, e.g. after release of oxygen, under oxygen deficiency or acidosis, aggregates are formed and hemolysis occurs.
The erythrocytes lose plasticity and assume a sickle-like shape. The sickle cells can then clump together in the smaller blood vessels and cause lethargy, resulting in infarctions of various organs with sometimes severe recurrent pain crises.
The brain, lungs, eyes, heart, kidneys, muscles and bones are particularly affected. Recurrent splenic infarctions are common, leading to prolonged spleen loss of function and significant patient infection.
The first symptoms appear after about three months after birth, when HbA should increasingly replace HbA0, which is replaced by diseased HbS in those affected. The disease mainly occurs in malaria-producing regions because it confers relative resistance to the tropical disease and thus represents a clear selective advantage. However, as a result of increasing migration, sickle cell anemia is increasingly being observed in Europe. The life expectancy is reduced and is around 50 years.