Thalassemia is inherited in an autosomal recessive manner. The genes are present on the chromosomes for expressing the globin, which is important in formation of hemoglobin. Any mutation of these genes may cause thalassemia.
How Is Thalassemia Inherited?
Hemoglobin is made up of, alpha globin and beta globin. The expression of alpha globin and beta globin is done by the genes present on the chromosomes, the genes responsible for expression of alpha globin HBA1 and HBA2. These are present in the pair on chromosome 16. The genes responsible for the expression of beta globin are HBB. It is present in single pair on chromosome 11. When any out of four genes of the alpha globin on chromosome 16 gets mutated, the condition is known as alpha thalassemia. When any out of two genes responsible for expressing beta globin is mutated, the condition is known as beta thalassemia.
The severity of the thalassemia depends upon the number of genes that gets mutated. More the number of genes get mutated, more severe the symptoms and more aggressive treatment is required. Mutation in the related genes may result in either reduced or complete absence of normal hemoglobin synthesis. This leads to the loss of RBC.
The characteristic symptom is presence of anemia. The inheritance of thalassemia disease follows the recessive inheritance. Thus, if only a single gene is mutated, the other copy makes up the loss for mutated gene and the patient experiences no or very mild symptoms. Thus, in order to manifest the symptoms, both the copies should be mutated. The person with mutation in one gene is called as carrier and they chance of inheritance of this gene is 50%.
If both the parents are carrier then there is 50% chance that the offspring will be carrier, 25% chance of being normal and 25% chance of being diseased. The mild form of the disease is termed as thalassemia minor and severe form of the disease is termed as thalassemia major.
Thalassemia is the condition in which there is a production of abnormal hemoglobin. Hemoglobin is made up of two alpha and two beta globin units. The expression of this globin is controlled by the genes. Any mutation in these genes causes thalassemia. In this condition, the hemoglobin is abnormal, thus the bone marrow is not able to produce sufficient number of red blood cells. Thus, this condition may lead to anemia.
The symptoms of this condition start noticing after 6 months as till 6 months, the infant produces fetal hemoglobin which is not expressed by these genes. The standard therapy for managing the severe form of disease is blood transfusion, but it may have disadvantages such as iron overload. Stem cell transplantation, counseling and interruption in pregnancy are other measures used in thalassemia.
Thalassemia Symptoms
Hemoglobin is an importation component of the blood which is a fluid connective tissue. The function of hemoglobin is to carry the oxygen to different parts of the body and the red blood cells are produced in bone marrow. Thalassemia is the disease related to production of abnormal hemoglobin and this may cause variety of symptoms. Following are the symptoms and complications experienced by the patients suffering from thalassemia:
Fatigue: Hemoglobin is required in the body for carrying oxygen to various organs of the body. The tissues of the organ use oxygen and produce energy. Presence of abnormal hemoglobin either reduces the capacity to carry oxygen or may completely stops the process. This may lead to severe fatigue.
Bone Deformation: As the bone marrow, this produces red blood cells, starts growing to produce more red blood cells, leading to bone deformation.
Iron Overload: Due to frequent blood transfusion, there is an iron overload. It is a symptom of thalassemia.
Pale Skin: As hemoglobin is responsible for imparting reddish color to skin, low level of hemoglobin makes the skin pale.
Anemia: Anemia is one of the major symptoms of thalassemia.
Conclusion
The genes responsible for thalassemia are present on chromosome 11 and chromosome 16. Any mutation in these genes causes thalassemia. The severity of disease depends upon the number of genes that gets mutated.
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