The thalassemias are a group of genetic diseases, which cause anemia in the affected person. They are inherited, and vary from mild cases that are found only by coincidence, to the very severe forms that cause death of a baby before birth.
The defect is in the hemoglobin -- the protein in the red blood cells (RBCs) that carries oxygen all over the body. Presence of defective hemoglobin leads to large scale destruction of the RBCs, and the body attempts to compensate by producing more and more red blood cells -- all with defective hemoglobin.
There are two types of protein chains in hemoglobin, the alpha and beta chains. Depending on which chain is affected, the disease is named alpha or beta thalassemia. A very severe form of alpha thalassemia causes death of the baby in the uterus. Another type is much milder, causing mild anemia and enlargement of the spleen.
What we see most often is beta thalassemia. Thalassemia minor or thalassemia trait is a condition in which a person has one gene for the disease. These people have mild anemia, but go through life with no difficulty because of it. The problem occurs when two people with thalassemia have children -- each such child has a 25% chance of having two defective genes, and the full blown diseases known as thalassemia major.
Large amounts of defective hemoglobin are formed in the red blood cells, leading to their destruction in the body. The body recruits all the blood forming capacity it has in the the bone marrow, in a vain effort to have enough circulating hemoglobin to satisfy the oxygen requirements of the various organs. These children look pale, are short, and get frequent infections.
These children need regular blood transfusions for survival. Regular transfusions allow them to have a near normal life in childhood, and grow into young adulthood.
Blood transfusions are needed for the child to survive and grow. As the child becomes older, blood is needed more and more frequently. In some places, blood is not easily available.
Regular transfusions help the child's growth and overall health, but load the body with iron. Iron accumulates in the heart, liver, bone marrow, and other organs, and causes these organs to malfunction. People with thalassemia often die in their twenties because of liver or heart failure.
Iron overload can be prevented by chelation therapy. The established drug is desferrioxamine, but is not easy to use. It has to be given by infection under the skin by a pump, and each dose requires several hours. Children need 4-6 doses a week; the therapy is arduous. Another drug, deferipone, can be taken by mouth, but has some dangerous side effects.
Last Revision: February 16, 2016
This requires testing of the unborn baby, during pregnancy, for thalassemia. Couples who know they both have thalassemia minor should opt for this testing. If the child is found to have thalassemia major (a 25% chance with each pregnancy), the couple have the option of terminating the pregnancy. This approach has been successfully used in places like Cyprus and Sardinia to reduce the number of children born with thalassemia.
DNA testing has made possible the diagnosis of thalassemia as early as the twelfth week of pregnancy. This method identifies 90% of babies with thalassemia major. Where this is not available, the older method of fetal blood sampling can be done at 18 weeks. The baby's blood can then be analysed for the proportion of alpha and beta chains to make the diagnosis.
Earlier, a child with thalassemia just took transfusions till death, usually in the second decade of life. Currently, however, a cure for thalassemia is available.
Bone marrow transplantation replaces the affected child's bone marrow with that of a healthy donor. The child then produces normal hemoglobin, and needs no further transfusions. However, bone marrow transplantation is risky, expensive, and a matching donor is not always available.
Dr. Parang Mehta,
Opposite Putli, Sagrampura,
Surat, India. Tel: +91 9429486624.
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