Thalassemia is an inherited autosomal recessive blood disease. In thalassemia, the genetic defect results in reduced rate of synthesis of one of the globin chains that make up hemoglobin. Reduced synthesis of one of the globin chains can cause the formation of abnormal hemoglobin molecules, thus causing anemia, the characteristic presenting symptom of the thalassemias.
Sickle-Cell Anemia (SCA, also called SSA, the name of the responsible mutation) or drepanocytosis, is a genetic life-long blood disorder characterized by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases the cells' flexibility and results in a risk of various complications. The sickling occurs because of a mutation in the haemoglobin gene. Life expectancy is shortened, with studies reporting an average life expectancy of 42 and 48 years for males and females, respectively.
Normally, humans have Haemoglobin A, which consists of two alpha and two beta chains, Haemoglobin A2, which consists of two alpha and two delta chains and Haemoglobin F, consisting of of two alpha and two gamma chains in their bodies. Of these, Haemoglobin A makes up around 96-97% of the normal haemoglobin in humans.
In normal Haemoglobin A, glutamic acid is on the 6th position of the beta chain, while in sickle-cell disease, this glutamic acid is replaced by valine leading to the formation of sickle cells. This happens due to a one point mutation. This leads to polymerization of the two beta chains and therefore their appearance as puzzle pieces (or lock and key); which means they fit into each other forming a longitudinal polymer that would lead to the cell becoming deformed and very rigid leading to vessel occlusion. This process of polymerization can be activated by infections, hypoxia, acidosis, physical exercise, vasoocclusion due to cold as well as hypertonic dehydration.
Children born with sickle-cell disease will undergo close observation by the pediatrician and will require management by a hematologist to assure they remain healthy. These patients will take a 1 mg dose of folic acid daily for life. From birth to five years of age, they will also have to take penicillin daily due to the immature immune system that makes them more prone to early childhood illnesses
- Sickle-cell conditions are inherited from parents in much the same way as blood type, hair color and texture, eye color, and other physical traits.
- The types of haemoglobin a person makes in the red blood cells depend on what haemoglobin genes are inherited from his parents
Bone marrow transplants have proven to be effective in children. (HSCT) is the transplantation of blood stem cells derived from the bone marrow or blood. Stem cell transplantation is a medical procedure in the fields of hematology and oncology, most often performed for people with diseases of the blood, bone marrow, or certain types of cancer.