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Thalassemia is actually a group of inherited diseases of the blood that affect
a person's ability to produce hemoglobin, resulting in anemia. Hemoglobin is
a protein in red blood cells that carries oxygen and nutrients to cells in the
body. About 100,000 babies worldwide are born with severe forms of thalassemia
each year. Thalassemia occurs most frequently in people of Italian, Greek, Middle
Eastern, Southern Asian and African Ancestry.
The two main types of thalassemia are called "alpha" and "beta," depending
on which part of an oxygen-carrying protein in the red blood cells is lacking.
Both types of thalassemia are inherited in the same manner. The disease is passed
to children by parents who carry the mutated thalassemia gene. A child who inherits
one mutated gene is a carrier, which is sometimes called "thalassemia trait."
Most carriers lead completely normal, healthy lives.
A child who inherits two thalassemia trait genes - one from each parent - will
have the disease. A child of two carriers has a 25 percent chance of receiving
two trait genes and developing the disease, and a 50 percent chance of being
a thalassemia trait carrier.
Most individuals with alpha thalassemia have milder forms of the disease, with
varying degrees of anemia. The most severe form of alpha thalassemia, which
affects mainly individuals of Southeast Asian, Chinese and Filipino ancestry,
results in fetal or newborn death.
A child who inherits two copies of the mutated gene for beta thalassemia will
have beta thalassemia disease. The child can have a mild form of the disease,
known as thalassemia intermedia, which causes milder anemia that rarely requires
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The more severe form of the disease is thalassemia major, also called Cooley's
Anemia. It is a serious disease that requires regular blood transfusions and
extensive medical care.
Those with thalassemia major usually show symptoms within the first two years
of life. They become pale and listless and have poor appetites. They grow slowly
and often develop jaundice. Without treatment, the spleen, liver and heart soon
become greatly enlarged. Bones become thin and brittle. Heart failure and infection
are the leading causes of death among children with untreated thalassemia major.
The use of frequent blood transfusions and antibiotics has improved the outlook
for children with thalassemia major. Frequent transfusions keep their hemoglobin
levels near normal and prevent many of the complications of the disease. But
repeated blood transfusions lead to iron overload - a buildup of iron in the
body - that can damage the heart, liver and other organs. Drugs known as "iron
chelators" can help rid the body of excess iron, preventing or delaying problems
related to iron overload.
Thalassemia has been cured using bone marrow transplants. However, this treatment
is possible only for a small minority of patients who have a suitable bone marrow
donor. The transplant procedure itself is still risky and can result in death.
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Scientists are working to develop a gene therapy that may offer a cure for
thalassemia. Such a treatment might involve inserting a normal beta globin gene
(the gene that is abnormal in this disease) into the patient's stem cells, the
immature bone marrow cells that are the precursors of all other cells in the
Another form of gene therapy could involve using drugs or other methods to
reactivate the patient's genes that produce fetal hemoglobin - the form of hemoglobin
found in fetuses and newborns. Scientists hope that spurring production of fetal
hemoglobin will compensate for the patient's deficiency of adult hemoglobin.
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Blood tests and family genetic studies can show whether an individual has thalassemia
or is a carrier. If both parents are carriers, they may want to consult with
a genetic counselor for help in deciding whether to conceive or whether to have
a fetus tested for thalassemia.
Prenatal testing can be done around the 11th week of pregnancy using chorionic
villi sampling (CVS). This involves removing a tiny piece of the placenta. Or,
the fetus can be tested with amniocentesis around the 16th week of pregnancy.
In this procedure, a needle is used to take a sample of the fluid surrounding
the baby for testing.
Assisted reproductive therapy is also an option for carriers who don't want
to risk giving birth to a child with thalassemia. A new technique, pre-implantation
genetic diagnosis (PGD), used in conjunction with in vitro fertilization, may
enable parents who have thalassemia or carry the trait to give birth to healthy
babies. Embryos created in-vitro are tested for the thalassemia gene before
being implanted into the mother, allowing only healthy embryos to be selected.
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