thalassemias

Why do thalassemias occur and what are their types?

Thalassemias produce a decrease in hemoglobin, the symptoms are the same as anemias and treatment depends on the degree of involvement.

Thalassemia is a set of genetic diseases that produce a decrease in the production of some of the globin chains , which make up hemoglobin, and are the most frequent genetic diseases in the world. With this, thalassemias produce a decrease in hemoglobin . This is a molecule found in red blood cells, or red blood cells, which is made up of four parts called chains: two alpha chains and two beta chains . Depending on the chain in which the defect occurs, we can find ourselves before:

  • Alpha thalassemia: occurs when there is insufficient production of alpha globin. It is most prevalent in areas of Southeast Asia and China, the Middle East, and Africa.
  • Beta thalassemia: it is caused by an altered production of beta globin. This thalassemia is frequent in Spain and in other countries of the Mediterranean area.

Diseases that produce a decrease in hemoglobin, whose function is to transport oxygen to the tissues, produce some of the different types of anemia . Therefore, the symptoms produced by thalassemia will be the same as anemia, although there are differences depending on the type of chain affected and the degree of involvement:

Beta thalassemia

People who have thalassemia trait or thalassemia minor (heterozygotes or carriers of a defective gene for beta-chain production) may not develop anemia or may have mild anemia, so they may not have any symptoms. It is the most common form of the disease.

Homozygotes , or carriers of two defective genes, suffer from thalassemia major, which is a very serious disease, since they cannot form beta chains that work properly. When the body detects that the red blood cells are defective, it destroys them, and the bone marrow, where the blood cells are generated, tries to compensate by producing more red blood cells, which ends up causing an exaggerated growth that produces complications such as deformities and bone fractures in childhood and enlargement of the liver and spleen as they try to help the bone marrow make more red blood cells. This can become incompatible with life and lead to death at an early age.

Alpha thalassemia

Each alpha chain of hemoglobin is made up of two different parts , so we have two genes from each parent. This means that it is more difficult to have a higher grade alpha thalassemia, since we would have to inherit twice as many defective genes as in beta thalassemia.

People who have alpha thalassemia trait, or who have alpha-thalassemia-1, don’t have any symptoms and usually don’t show any abnormalities in their red blood cells. Those with two defective genes, or who have alpha-thalassemia-2, show symptoms and manifestations similar to beta thalassemia trait, so they will only have mild anemia or a small alteration in the size of the red blood cells.

Those who suffer from the mutation of three genes of the alpha chain of hemoglobin produce a hemoglobin called H, or HbH, suffer from moderate-severe anemia, similar to an intermediate degree of beta-thalassemia, and can reach adulthood.

The mutation of the four genes that produce the alpha chains causes the death of the fetus before birth.

How is it diagnosed

For the confirmation diagnosis of thalassemia, a specific study of hemoglobin is required, which will be requested when anemia with very small red blood cells appears in an analysis and the iron is normal , since small red blood cells appear only in thalassemias and in anemias iron deficiency , or due to lack of iron.

How it is treated

Treatment will depend on the degree of involvement:

  • Generally, thalassemia trait (beta or alpha) does not require any treatment.
  • Patients with HbH require occasional blood transfusions . Over time, removal of the spleen or splenectomy may be necessary .
  • People with beta thalassemia major require frequent blood transfusions from infancy. This ends up producing a serious iron overload that generates problems such as diabetes, cirrhosis and heart disease. For this reason, treatment with drugs that eliminate iron from the body, or chelators, is also needed, and it may become necessary to perform a splenectomy. In addition , treatment with folic acid is usually associated to help generate red blood cells.

Finally, in the case of couples who suffer from thalassemia trait and want to have children, genetic counseling can be useful to avoid offspring with thalassemia major. If their own disease is discovered late in the pregnancy, a genetic study of the fetus for thalassemia major may be done to help the couple decide whether to continue or terminate the pregnancy.

What you should know…

  • Thalassemia is a set of genetic diseases that produce a decrease in the production of some of the globin chains, which make up hemoglobin, and are the most frequent genetic diseases in the world.
  • Diseases that produce a decrease in hemoglobin, whose function is to transport oxygen to the tissues, produce some of the different types of anemia.
  • Treatment will depend on the degree of involvement. Generally, thalassemia trait (beta or alpha) does not require any treatment.
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