Thalassemia is an inherited blood disorder characterized by decreased hemoglobin production. Symptoms depend on the type and can vary from none to severe. Often there is mild to severe anemia(low red blood cells or hemoglobin). Anemia can result in feeling tired and having a pale skin. There may also be bone problems, an enlarged spleen, yellowish skin and dark urine. Slow growth may occur in children. Thalassemia is a genetic disorder inherited from a person’s parents. As of 2015, thalassemia occurs in about 280 million people, with about 439,000 having severe disease. It is most common among the people of Italian, Greek, Turkish, Middle Eastern, South Asian and African descent. Males and Females have similar rates of disease. It resulted in 16,800 deaths in 2015, down from 36,000 deaths in 1990. Those who have minor degrees of thalassemia similar to those with sickle-cell trait, have some protection against malaria, explaining why they are more common in regions of the world where malaria exists.
Thalassemia is caused by mutations in the DNA of the cells that make up the hemoglobin- the substance in red blood cells that carries oxygen throughout the body. The mutations associated with thalassemia are passed from parents to the offsprings. Hemoglobin molecules are made up of chains called alpha and beta chains that can be affected by mutations. In thalassemia, the production of either the alpha or beta chains are reduced, resulting in either alpha-thalassemia or beta-thalassemia.
In alpha-thalassemia, the severity of thalassemia depends on the number of gene mutation inherited from the parents. The more mutated genes, the more severe is the thalassemia. In beta-thalassemia, the severity of thalassemia depends on which part of the hemoglobin molecule is affected.
Four genes are involved in making the alpha hemoglobin chain. We get one from each parent. If inherited:-
- one mutated gene- no signs or symptoms of thalassemia but the person is a carrier of the disease and can pass it on to the children.
- two mutated genes- signs and symptoms of thalassemia are mild. This condition might be called alpha thalassemia trait.
- three mutated genes- signs and symptoms will be moderate to severe.
Inheriting four mutated genes is rare and usually results in stillbirths. Babies born with this condition often die shortly after birth or require lifelong transfusion therapy. In rare cases, a child born with this condition can be treated with transfusion and a stem cell transplant.
Two genes are involved in making the beta hemoglobin chain. We get one from each parent. If inherited:-
- one mutated gene- mild signs and symptoms. This condition is called thalassemia minor or beta-thalassemia.
- two mutated genes- signs and symptoms will be moderate to severe. This condition is called thalassemia major or Cooley Anemia.
Babies born with two defective beta hemoglobin genes usually are healthy at birth but develop signs and symptoms within the first two years of life. A milder form, called thalassemia intermedia, also can result from two mutated genes.
- Family history of thalassemia- thalassemia is passed from parents to children through mutated hemoglobin genes.
- certain ancestry.