Thalassemia: All that you need to know about it.
Thalassemia is a form of inherited autosomal recessive blood disorder characterized by abnormal formation of hemoglobin. The abnormal hemoglobin formed results in improper oxygen transport and destruction of red blood cells. Thalassemia is caused by variant or missing genes that affect how the body makes hemoglobin, the protein in red blood cells that carries oxygen. People with thalassemia make less hemoglobin and have fewer circulating red blood cells than normal, which results in mild or severe anemia.
Thalassemia can cause complications, including iron overload, bone deformities, and cardiovascular illness. However, this same inherited disease of red blood cells may confer a degree of protection against malaria (specifically, malaria caused by the protozoan parasite Plasmodium falciparum). This selective survival advantage of carriers (known as heterozygous advantage) may be responsible for perpetuating the mutation in populations. In that respect, the various thalassemias resemble another genetic disorder affecting hemoglobin, sickle-cell disease.
- Iron overload: People with thalassemia can get an overload of iron in their bodies, either from the disease itself or from frequent blood transfusions. Too much iron can result in damage to the heart, liver, and endocrine system, which includes glands that produce hormones that regulate processes throughout the body. The damage is characterized by excessive deposits of iron.
- Infection: People with thalassemia have an increased risk of infection. This is especially true if the spleen has been removed.
- Bone deformities: Thalassemia can make the bone marrow expand, which causes bones to widen. Bone marrow expansion also makes bones thin and brittle, increasing the risk of broken bones.
- Enlarged spleen: The spleen aids in fighting infection and filters unwanted material, such as old or damaged blood cells. Thalassemia is often accompanied by the destruction of a large number of red blood cells and the task of removing these cells causes the spleen to enlarge. Splenomegaly can make anemia worse, and it can reduce the life of transfused red blood cells. Severe enlargement of the spleen may necessitate its removal.
- Slowed growth rates: Anemia can cause a child’s growth to slow. Puberty also may be delayed in children with thalassemia.
- Heart problems: Diseases, such as congestive heart failure and abnormal heart rhythms, may be associated with severe thalassemia.
Both α- and β-thalassemias are often inherited in an autosomal recessive manner. For the autosomal recessive forms of the disease, both parents must be carriers for a child to be affected. If both parents carry a hemoglobinopathy trait, the risk is 25% for each pregnancy for an affected child.
On the brighter side of things, having a single gene for thalassemia may protect against malaria and thus be an advantage. People diagnosed with heterozygous (carrier) β-thalassemia have some protection against coronary heart disease.