It is impossible within the scope of the material presented here to take up all of the possible disorders of the blood and the lymph-associated organs. Here the disorders that are the most relevant will be treated.
Hemoglobinopathies are congenital disorders of the hemoglobin synthesis as a result of various genetic defects in the formation of the α or β chains.
Quantitative hemoglobinopathies (thalassemias)
Thalassemias are a group of autosomal-recessive hereditary diseases in which the synthesis of a globin chain is affected. In a disorder of the b chain synthesis a β-thalassemia is present while if the a chain is affected, this is termed an α-thalassemia. Thalassemias are mostly due to a mutation of the regulatory DNA sequence (LCR).
Also see: Hemoglobin.
Structural hemoglobinopathies (sickle cell syndrome)
The congenital structural changes of individual hemoglobin chains are due to a mutation of the corresponding genes. The most frequent hemoglobinopathy is the homozygous form of sickle cell anemia (Hb-SS disease). It arises due to a mutation of the β globin gene on chromosome 11p15.4. This results in an exchange of glutamine acid and valine at position 6 of the β chain. When the oxygen concentration is low, the HbS changes its 3D configuration and forms aggregates that lead to a sickle shape of the erythrocytes. These rigid erythrocytes become especially sequestered in the spleen and can, in addition, lead to vessel blockages.
Also see: Spleen diagram with open and closed circulation.