Thalassemias are a heterogeneous group of inherited anemia that lead to a diminished or lack of synthesis of one or more globin chains (proteins that comprise hemoglobin). It is a blood disorder passed down through families (inherited) in which the body makes an abnormal form of hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen. The disorder results in large numbers of red blood cells being destroyed, which leads to anemia.
Hemoglobin is made of two proteins: Alpha globin and beta globin. Thalassemia occurs when there is a defect in a gene that helps control production of one of these proteins.
There are two main types of thalassemia:
- Alpha thalassemia occurs when a gene or genes related to the alpha globin protein are missing or changed (mutated). Alpha thalassemias occur most often in persons from Southeast Asia, the Middle East, China, and in those of African descent.
- Beta thalassemia occurs when similar gene defects affect production of the beta globin protein. Beta thalassemias occur most often in persons of Mediterranean origin. To a lesser extent, Chinese, other Asians, and African Americans can be affected.
There are many forms of thalassemia. Each type has many different subtypes. Both alpha and beta thalassemia include the following two forms:
- Thalassemia major
- Thalassemia minor
You must inherit the gene defect from both parents to develop thalassemia major. Thalassemia minor occurs if you receive the faulty gene from only one parent. Persons with this form of the disorder are carriers of the disease. Most of the time, they do not have symptoms.
Beta thalassemia is a reduced production of the beta chain
- Beta thalassemic trait (thalassemia minor): generally without symptoms or slight manifestations of the disorder, sometimes including an enlarged spleen (splenomegaly). It usually does not need treatment.
Thalassemia major (also called Cooley´s anemia): severe form of congenital hemolytic anemia (homozygous state). 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: anemia (pale skin), apathetic, loss of appetite. It is also associated with slow growth, hepatosplenomegaly, jaundice (yellowing of skin and eyes) and bone deformities caused by medullar hypertrophy. Abnormal iron deposits in organs can generate an insufficiency in them (mainly affects, the heart, liver and pancreas). Thalassemia major often involves regular blood transfusions and folate supplements and strict control by a doctor.
The disorder is hereditary but blood analyses and studies of family genetics will detect a carrier. You may want to seek genetic counseling if you have a family history of the condition and are thinking of having children.
Risk factors for thalassemia include:
- Asian, Chinese, Mediterranean, or African American ethnicity
- Family history of the disorder
GENE OR REGION STUDIED