THALASSEMIA ARTIKEL

Thalassemia refers to a group of inherited diseases in which there is a defect in the production of one or more of the
globin chains of hemoglobin. These diseases are better referred to as the thalassemic syndromes because they
represent a spectrum of diseases rather than one specific disease.
Thalassemia is derived from a Greek word that refers to the Mediterranean Sea. Although these anemias are seen in
many areas of the world, they were originally noted in Italy and Greece around the Mediterranean Sea.
Hemoglobin is composed of heme (an iron molecule) and globin chains. Globin chains are polypeptide chains that
contain about 140 to 150 amino acids. There are four different chains, and each molecule of hemoglobin has four
heme radicals and four globin chains.
The main problem in thalassemia is that one of the globin chains is not produced in normal numbers or, possibly,
not produced at all. This leads to several problems. The most obvious is that there will be a decreased amount of
hemoglobin so the patient will be anemic. The degree of anemia will depend on how severe the production defect
is.
Probably the best way to explain is with an example. Hemoglobin A (the major hemoglobin) in normal adults has
two alpha and two beta chains. If there is a defect in producing the beta chains, it is termed beta thal. If the defect
is inherited from one parent, the decrease in synthesis of beta chains may be mild, resulting in red cells that are
smaller than normal (microcytosis) and stain lighter than normal (hypochromia). The anemia is usually mild and is
called thalassemia minor.
If, however, the defect is inherited from both parents (homozygous), there may be little or no hemoglobin A. This
results in a profound anemia with hypochromic, microcytic cells. These people have more of a problem than just
decreased production of hemoglobin; they also tend to build up excess alpha chains. This causes damage to the red
cells resulting in hemolysis of red cells, as well as an ineffective production of red cells.
The type of thalassemia is named after the deficient hemoglobin. People who do not produce beta chains have beta
thal; if it is heterozygous, they have beta thal minor. Similarly, deficient alpha chain production results in alpha
thalassemia. On occasions, the defect in hemoglobin production is so severe that a fetus does not survive, resulting
in a stillbirth. On the other hand, some people have persistence of fetal hemoglobin production into adulthood; these
people, afflicted with either thalassemia or sickle cell disease, are somewhat protected by their fetal hemoglobin. As
mentioned previously, these diseases are inherited.
Thalassemia major is a serious disease that affects people early in life. These individuals are severely anemic. As
there is no medication to cure the anemia, blood transfusions are necessary. The person has the usual complications
of transfusion but additionally, with frequent transfusions, more and more iron is stored in the body. This eventually
leads to liver and heart disease, which is often the cause of death in people with thalassemia major. The bone
marrow expands, leading to thinning of the bones with fractures and overgrowth especially of the bones of the skull.
Until recently, the only way to prevent iron overload was to give a chelating agent by way of a needle under the
skin. The drug had to be infused over many hours, obviously a difficult procedure for young children. More
recently, a pill form of iron chelation has been developed; it is hoped that this will provide a better solution.
In the past ten years or so, bone marrow transplantation has been used as a treatment for thalassemia major. Recent
data points out that age and the amount of storage iron in the body are major determinants of the success of
transplantation. Therefore, the earlier in life the transplant is done, the higher the success rate, although it should be
noted that there is a 10 to 20 percent mortality risk from the transplantation.
Thalassemia minor does not require any treatment; however, it is important to identify this problem. Once the
diagnosis is established, it prevents the patient from having unnecessary tests and treatment. Some excellent
materials are available from the Cooley’s Anemia Society regarding variants of the disease.

In summary, Thalassemia refers to a number of inherited anemias. The most common in this country is beta
thalassemia. It can be severe as in beta thal major; less severe although still with many symptoms, as in beta thal
intermedia; or with few symptoms, beta thal minor.