Thalassemias are a group of blood disorders that affect the way the body makes
hemoglobin. Hemoglobin is a protein found in red blood cells that carries oxygen throughout
the body. It's made up of alpha globin and beta globin.
The body contains more red blood cells than any other type of cell, and each has
a life span of about 4 months. Each day, the body produces new red blood cells to
replace those that die or are lost from the body.
With thalassemia, the red blood cells are destroyed at a faster rate, leading to
anemia, a condition that
can cause fatigue and other complications.
Thalassemias are inherited conditions — they're carried in the genes and
passed on from parents to children. People who are carriers of a thalassemia
gene show no thalassemia symptoms and might not know they're carriers. If both parents
are carriers, they can pass the disease to their kids. Thalassemias are not contagious.
While there are many different types of thalassemias, the main two are:
Alpha thalassemia: when the body has a problem producing alpha
When the gene that controls the production of either of these proteins is missing
or mutated, it results in that type of thalassemia.
About Alpha Thalassemia
Normally, each person has four genes for alpha globin. Alpha thalassemia happens
when one or more of the genes that control the making of alpha globins is absent or
defective. It can cause anemia ranging from mild to severe and is most commonly found
in people of African, Middle Eastern, Chinese, Southeast Asian, and, occasionally,
Some children with alpha thalassemia have no symptoms and require no treatment.
Others with more severe cases need regular blood transfusions to treat anemia and
A child can only get alpha thalassemia by inheriting it from his or her parents.
Genes are "building blocks" that play an important role in determining physical traits
and many other things about us.
Humans are made up of trillions of cells that form the structure of our bodies
and carry out specialized jobs like taking nutrients from food and turning them into
energy. Red blood cells, which contain hemoglobin, deliver oxygen to all parts of
All cells have a nucleus at their center, which is kind of like the brain or "command
post" of the cell. The nucleus directs the cell, telling it to grow, mature, divide,
or die. The nucleus contains DNA (deoxyribonucleic acid), a long, spiral-shaped molecule
that stores the genes that determine hair color, eye color, whether or not a person
is right- or left-handed, and many more traits. DNA, along with genes and the information
they contain, is passed down from parents to their children during reproduction.
Each cell has many DNA molecules, but because cells are very small and DNA molecules
are long, the DNA is packaged very tightly in each cell. These packages of DNA are
called chromosomes, and each cell has 46 of them. Each package is arranged into 23
pairs — with one of each pair coming from the mother and one from the father.
When a child has alpha thalassemia, there is a change in chromosome 16.
Alpha globin is made on chromosome 16. So, if any gene that tells chromosome 16
to produce alpha globin is missing or mutated, less alpha globin is made. This affects
hemoglobin and decreases the ability of red blood cells to transport oxygen around
Types of Alpha Thalassemia
Alpha globin is made by four genes and one or more can be mutated or missing, so
there are four kinds of alpha thalassemia:
One missing or abnormal gene makes a child a silent alpha thalassemia
carrier. Silent alpha thalassemia carriers have no signs or symptoms of the
disease, but are able to pass thalassemia on to their children.
Two missing or mutated genes is a condition called alpha thalassemia minor
or having alpha thalassemia trait. Children with this condition may
have red blood cells that are smaller than normal (microcytosis) and sometimes very
People with alpha thalassemia minor usually don't have any symptoms at all, but can
pass thalassemia on to their children. The two abnormal genes can be on the same chromosome
(called the cis position) or one on each chromosome (called the trans position). If
two genes on the same chromosome are affected, the person can pass along a two-gene
defect to his or her child. This situation is much more common in people of Asian
Three missing or mutated genes is called hemoglobin H disease.
Signs and symptoms will be moderate to severe.
Four missing or mutated genes is a condition known as alpha thalassemia
major or hydrops fetalis. This almost always leads to a
fetus dying before delivery or a newborn baby dying shortly after birth. However if
this disease is suspected because of a history in the family, it can be diagnosed
prenatally. Sometimes, if treatment is initiated before the baby is even born, the
baby can survive.
In addition to anemia and hydrops fetalis, severe cases of alpha thalassemia and
hemoglobin H disease can lead to serious complications, especially if untreated. Complications
of alpha thalassemia include:
Excess iron. When children have alpha thalassemia, they can end
up with too much iron in their bodies, either from the disease itself or from getting
repeated blood transfusions. Excess iron can cause damage to the heart, liver, and
Bone deformities and broken bones. Alpha thalassemia can cause
bone marrow to expand, making bones wider, thinner, and more brittle. This makes bones
more likely to break and can lead to abnormal bone structure, particularly in the
bones of the face and skull.
Enlarged spleen. The spleen helps fight off infections and filters
out unwanted materials, such as dead or damaged blood cells, from the body. Alpha
thalassemia can cause red blood cells to die off at a faster rate, making the spleen
work harder, which makes it grow larger. A large spleen can make anemia worse and
may need to be removed if it gets too big.
Infections. Children with alpha thalassemia have an increased
risk of infection, especially if they've had their spleens removed.
Slower growth rates. The anemia resulting from alpha thalassemia
can cause children to grow more slowly and also can lead to delayed puberty.
The signs and symptoms of alpha thalassemia vary depending on the type that a child
has and how severe it is. Children with alpha thalassemia trait and those who are
silent carriers have no symptoms at all.
Some of the more common symptoms of alpha thalassemia include:
fatigue, weakness, or shortness of breath
a pale appearance or a yellow color to the skin (jaundice)
deformities of the facial bones
a swollen abdomen
In most cases, alpha thalassemia is diagnosed before a child's second birthday
or through newborn screening, a blood test given when the child is first born. Children
with alpha thalassemia major may have a swollen abdomen or symptoms of anemia or failure to thrive.
If the doctor suspects alpha thalassemia, he or she will take a blood sample for
testing. Blood tests can reveal red blood cells that are pale, varied in shape and
size, or smaller than normal. They also can detect low red blood cell counts and cells
with an uneven distribution of hemoglobin, which causes them to look like a bull's-eye
when seen through a microscope.
Blood tests also can measure the amount of iron in the blood, evaluate hemoglobin,
and test a child's DNA for abnormal hemoglobin genes.
If both parents are carriers of the alpha thalassemia disorder, doctors can conduct tests on a fetus
before birth. This is done through either:
sampling, which takes place about 11 weeks into pregnancy and involves removing
a tiny piece of the placenta for testing
which is usually done about 16 weeks into the pregnancy and involves removing a sample
of the fluid that surrounds the fetus
The amount of treatment that alpha thalassemia requires depends on how severe the
symptoms are. For those with alpha thalassemia trait or silent carriers with only
mild anemia from time to time, no medical treatment is necessary.
However, the blood counts in alpha thalassemia trait look a lot like the blood
counts in iron deficiency anemia,
which is a very common disorder. It's important for doctors to know when children
have alpha thalassemia trait so that they do not treat them with iron if it's not
Doctors also might recommend a folic acid supplement for kids with hemoglobin H
disease to help the body make new red blood cells. In addition, these kids may require
an occasional blood transfusion, particularly after surgery.
Less commonly, children with severe cases of hemoglobin H disease may require regular
blood transfusions their entire lives to keep them healthy. During blood transfusions,
they're given blood from donors with matching blood types. Over time, this can cause
a build-up of iron in the body, so kids who receive frequent blood transfusions may
have to take medications to remove excess iron from their bodies.
Currently, the only cure for thalassemia is a procedure called a bone
marrow transplant (also called a stem cell transplant). Bone marrow, which is
found inside bones, produces blood cells. In a bone marrow transplant, a person is
first given high doses of radiation or drugs to destroy the defective bone marrow.
The bone marrow is then replaced with cells from a compatible donor, usually a healthy
sibling or other relative. Bone marrow transplants carry many risks, so they usually
are done only in the most severe cases of thalassemia.
Because living with alpha thalassemia can be challenging, people who are carriers
of alpha thalassemia trait may want to seek genetic
counseling if they're considering having children.
If your child has alpha thalassemia, support groups are available to help your
family cope with the obstacles presented by the disease.