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Beta Thalassemia
How common is beta thalassemia?
Thalassemia is the most common
inherited cause of anemia. Thousands of new beta thalassemia cases are
diagnosed each year. Cases have declined as prevention measures, like
screenings to identify people who carry thalassemia gene mutations, have
increased.
What causes beta thalassemia?
Beta thalassemia results from a
mutation (error) that limits beta-globin production in your body. Hemoglobin
consists of four protein chains, two alpha-globin chains and two beta-globin
chains. Mutations of the alpha-globin chain cause alpha thalassemia, while
mutations of the beta-globin chain cause beta thalassemia. A deficiency of
either globin chain damages and destroys the red blood cell.
You inherit the gene mutation for
beta thalassemia in an autosomal recessive pattern. This happens when both
biological parents carry one copy of the mutated gene and one copy of the
normal gene. In the most severe form of beta thalassemia, you inherit a copy of
the mutated gene from both parents.
In rare instances, inheriting just
one mutated beta-globin gene causes beta thalassemia. This is called an
autosomal dominant pattern.
What are the types of beta
thalassemia?
The number of defective genes you
inherit and the mutation’s location will determine your condition’s severity.
Some mutations cause no beta-globin to be produced (beta-zero thalassemia).
Other mutations cause too little beta-globin to be made (beta-plus
thalassemia).
The types of beta thalassemia
include the following.
Beta thalassemia major (Cooley’s
anemia) is the most severe kind of beta thalassemia. It involves having two
missing or defective beta-globin genes. Beta thalassemia major is now known as
“transfusion-dependent thalassemia” because people with this condition require
lifelong blood transfusions.
Beta thalassemia intermedia may
cause mild to moderate anemia symptoms. It also involves having two missing or
defective beta-globin genes. You likely won’t need lifelong blood transfusions
with beta thalassemia intermedia.
Beta thalassemia minor (beta
thalassemia trait) often causes mild anemia symptoms. It involves having one
missing or defective beta-globin gene. Some people with beta thalassemia minor
don’t have symptoms at all.
What are the symptoms of beta
thalassemia?
Your symptoms will depend on how
severe your beta thalassemia is. For instance, you may be asymptomatic (no
symptoms) or have mild anemia symptoms with beta thalassemia minor. You may
have moderate or more severe symptoms with beta thalassemia intermedia and
especially beta thalassemia major.
Mild symptoms
Beta thalassemia minor (beta
thalassemia trait) is associated with mild anemia symptoms, including:
Fatigue.
Dizziness or weakness.
Frequent headaches.
Pale skin.
Moderate to severe symptoms
The most severe symptoms are
associated with beta thalassemia major. Some of these symptoms also appear with
beta thalassemia intermedia, depending on your condition's severity. In
addition to experiencing mild symptoms, you may have:
Shortness of breath with exertion.
Heart palpitations.
Yellow skin or whites of your eyes
(jaundice).
Dark or tea-colored urine (pee).
Slow growth or delayed development.
Swollen abdomen.
Weak or misshapen bones in your
arms, legs and face.
Infants with moderate to severe beta
thalassemia may be especially fussy and get frequent infections.
How is beta thalassemia diagnosed?
Beta thalassemia is often diagnosed
in childhood. Beta thalassemia major, the most severe form, is diagnosed early
in childhood, by age 2. Your doctor will diagnose beta thalassemia based on
your symptoms and blood test results.
What tests will be done to diagnose
beta thalassemia?
Your doctor will diagnose beta
thalassemia by performing a simple blood draw and analyzing the sample. Tests
may include:
A complete blood count (CBC): A CBC
provides information about your blood cells, including your red blood cells. It
can show whether you have too few red blood cells and if they’re smaller than
usual, oddly shaped or pale (light red). These characteristics may be signs of
thalassemia.
Reticulocyte count: Immature red
blood cells are called reticulocytes. A low reticulocyte count indicates that
your body isn’t producing enough red blood cells. Severe thalassemia is usually
accompanied by an elevated reticulocyte count. This is because your body is
trying to make more red cells to make up for the destruction of the red cells
containing the abnormal hemoglobin.
Molecular genetic testing: Molecular
genetic testing allows your doctor to study your hemoglobin closely and
identify the mutation associated with beta thalassemia.
Hemoglobin electrophoresis: A
hemoglobin electrophoresis test measures different types of hemoglobin proteins
in your blood. Certain types of hemoglobin proteins are increased with beta
thalassemia, while other types are decreased.
Your doctor may perform chorionic
villus sampling (CVS) or amniocentesis during pregnancy if there’s a concern
that your fetus may carry the mutated gene. CVS tests a portion of the placenta
for signs of the gene mutation. The placenta is the organ that allows you and
your fetus to share nutrients during pregnancy. Amniocentesis tests the fluid
surrounding your fetus for signs of beta thalassemia.
How is beta thalassemia treated?
You’ll likely work with a care team
that includes multiple specialists. Working with an experienced hematologist, a
specialist who treats blood disorders, is especially important.
Treatments may include:
Blood transfusions: You may need
frequent blood transfusions (as much as every two weeks) with beta thalassemia
major. During the procedure, you receive blood from a donor. The influx of
blood from a transfusion supplies red blood cells needed to carry oxygen to
tissues throughout your body.
Iron chelation therapy: Iron is an
important part of the hemoglobin protein allowing it to carry oxygen. Too much
iron, however, can be harmful. Iron chelation therapy can help prevent iron
overload.
Folic acid supplements: Folic acid
can help boost your body’s ability to make red blood cells. Your doctor may
recommend supplements if you have beta thalassemia minor. You may also take
folic acid in addition to receiving regular blood transfusions if your
condition is more severe.
Luspatercept: If you have severe
thalassemia, you may receive an injection (shot) of luspatercept every three
weeks to help your body make more red blood cells. Luspatercept improves anemia
in people diagnosed with beta thalassemia who are receiving blood transfusions.
Bone marrow and stem cell
transplant: You may receive bone marrow stem cells from a donor. Bone marrow
stem cells eventually mature into red blood cells. Replacing your bone marrow
stem cells with the stem cells of a healthy donor can cure beta thalassemia.
Unfortunately, finding a compatible donor can be a challenge. Also, this type
of transplant is considered a high-risk procedure.
What are the complications or
potential side effects of treatment?
The most common treatment
complication is iron overload. Blood transfusions introduce more red blood
cells and iron into your body. After many transfusions, excess iron can
accumulate and damage vital organs like your liver, heart and pancreas. Talk
with your doctor to determine how frequently you should receive iron chelation
therapy to remove excess iron from your body if you’re receiving regular
transfusions.
How can I reduce my risk of beta
thalassemia?
You can’t reduce your risk of
inheriting the gene mutation associated with beta thalassemia. However, you can
prevent passing it to your child. Talk to your doctor about screening for beta
thalassemia if you or your partner are a potential carrier and considering
having a baby.
Is beta thalassemia curable?
The only known cure for beta
thalassemia is a bone marrow and stem cell transplant from a compatible donor.
Unfortunately, finding a compatible donor is often difficult. Even family
members may not be considered compatible donors.
Researchers are currently studying
other potential cures for beta thalassemia, such as replacing defective genes
with healthy ones (gene therapy). This work is still in its early stages.
What is the life expectancy of
someone with beta thalassemia?
Beta thalassemia is treatable. With
minor and moderate forms of beta thalassemia, you can expect an average lifespan
if you follow your doctor’s treatment guidance. Beta thalassemia major can
shorten your lifespan. The most common cause of death is heart failure due to
iron overload.
Talk to your doctor about your
prognosis based on the severity of your condition.