How Is Thalassemia Transmitted?
Thalassemia is a genetic disease and the disease is transmitted from the parents to the baby. The disease is inherited in autosomal recessive pattern. The disease is caused due to mutation in genes controlling synthesis of hemoglobin.
Thalassemia is a genetic disorder which is inherited from the patients. If both the parents are the carrier, the chances of occurrence of the normal baby are 25%. Thus, the chances of transfer of the mutated gene in the baby are 75% in which 50% chance is of Carrier and 25% chance is of the diseased baby. Hemoglobin is composed of heme, alpha globin and beta globin. The synthesis of alpha and beta globin is controlled by the expression of genes.
The genes controlling the expression of synthesis of alpha globin are HBA1 and HBA2 and are present on chromosome 16. The genes controlling the expression of synthesis of beta globin is HBB and is present on chromosome 11. One pair of HBA1 and one pair of HBA2 is present while the HBB exists in single pair. This indicates that the synthesis of alpha globin is controlled by four genes while the synthesis of beta globin is controlled by 2 genes.
When the mutation takes place in genes of alpha globin, the disease is called alpha thalassemia while the mutation in genes of beta globin results in beta thalassemia. The severity of the disease depends upon the number of genes that gets mutated. Thalassemia is inherited in autosomal recessive pattern. It implies that mutation in both the alleles is required to manifest the symptoms of the disease.
In small percentage of patients, the genes of beta thalassemia may also show autosomal dominant pattern which means mutation in a single allele is sufficient to manifest the symptoms of the disease.
With the advent of new technology and implementation of highly sophisticated DNA techniques, various treatment options are available to the patients. Thalassemia can be managed as well as treated. Although options to cure the disease are not available to the eligible patients due to various factors and the condition is generally managed in majority of the patients. Following are the treatment options which are available or under the clinical trial:
Blood Transfusion: Thalassemia is the condition in which the abnormal hemoglobin is synthesized due to the mutation in the genes responsible for the synthesis of alpha globin and beta globin, the important component of hemoglobin. This faulty hemoglobin also causes the reduction in red blood cells as bone marrow is unable to synthesize adequate red blood cells with the faulty hemoglobin. This results in mild, moderate or severe anemia. To manage the symptoms, frequent blood transfusion is required, and the frequency depends upon the severity of the disease.
Iron Chelation Therapy: Due to frequent blood transfusion, the iron load of the body increases leading to iron toxicity. The excess iron starts accumulating the vital organs such as liver and heart. This condition becomes more sever due to increased gastric iron absorption and reduced formation of red blood cells. Iron chelation therapy is recommended in such patients and due to incorporation of iron therapy in the thalassemia patient’s treatment regimen, the mortality is significantly reduced.
Gene Therapy: Gene therapy is another thalassemia treatment approach in which the faulty genes are replaced by the correct genes. The transfer of genes is done through various processes. The most effective process is transfer of genes through oncoretroviral or lentiviral vectors. The other techniques involve splice-switching and stop codon readthrough.
Stem Cell Transplant: Stem cell transplant is transplanting the stem cells from a healthy donor to thalassemia person. Stem cells give rise to various cells such as red blood cells, white blood cells and platelets. Stems cells, when taken from bone marrow for transplanting, is termed as bone marrow transplantation.
Surgery: Surgery is done in the patients who have bone deformation due to thalassemia.
Thalassemia is autosomal recessive condition but in some cases of beta thalassemia, the condition is inherited in autosomal dominant manner. The gene controlling the synthesis of alpha and beta globin gets mutated resulting in abnormal hemoglobin synthesis.