thalassemia

Thalassemias are inherited blood disorders characterized by abnormal hemoglobin production.[7] Symptoms depend on the type and can vary from none to severe.[1] Often there is mild to severe anemia (low red blood cells).[1] Anemia can result in feeling tired and pale skin.[1] There may also be bone problems, an enlarged spleen, yellowish skin, dark urine, and among children slow growth.[1]
Thalassemias are genetic disorders inherited from a person's parents.[2] There are two main types, alpha thalassemia and beta thalassemia.[7] The severity of alpha and beta thalassemia depends on how many of the four genes for alpha globin or two genes for beta globin are missing.[2] Diagnosis is typically by blood tests including a complete blood count, special hemoglobin tests, and genetic tests.[3] Diagnosis may occur before birth through prenatal testing.[8]
Treatment depends on the type and severity.[4] Treatment for those with more severe disease often includes regular blood transfusions, iron chelation, and folic acid.[4] Iron chelation may be done with deferoxamine or deferasirox.[4] Occasionally, a bone marrow transplant may be an option.[4] Complications may include iron overload from the transfusions with resulting heartor liver disease, infections, and osteoporosis.[1] If the spleen becomes overly enlarged, surgical removal may be required.[1]
As of 2013, thalassemia occurs in about 280 million people, with about 439,000 having severe disease.[9] It is most common among people of Italian, Greek, Middle Eastern, South Asian, and African descent.[7] Males and females have similar rates of disease.[10] It resulted in 16,800 deaths in 2015, down from 36,000 deaths in 1990.[11][6] Those who have minor degrees of thalassemia, similar to those with sickle-cell trait, have some protection against malaria, explaining why they are more common in regions of the world where malaria exists.[12]



Thalassemia

Thalassemia is a blood disorder passed down through families (inherited) in which the body makes an abnormal form or inadequate amount of hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen. The disorder results in large numbers of red blood cells being destroyed, which leads to anemia.



Causes

Hemoglobin is made of two proteins:
  • Alpha globin
  • Beta globin
Thalassemia occurs when there is a defect in a gene that helps control production of one of these proteins.
There are two main types of thalassemia:
  • Alpha thalassemia occurs when a gene or genes related to the alpha globin protein are missing or changed (mutated).
  • Beta thalassemia occurs when similar gene defects affect production of the beta globin protein.
Alpha thalassemias occur most often in people from Southeast Asia, the Middle East, China, and in those of African descent.
Beta thalassemias occur most often in people of Mediterranean origin. To a lesser extent, Chinese, other Asians, and African Americans can be affected.
There are many forms of thalassemia. Each type has many different subtypes. Both alpha and beta thalassemia include the following two forms:
  • Thalassemia major
  • Thalassemia minor
You must inherit the gene defect from both parents to develop thalassemia major.
Thalassemia minor occurs if you receive the faulty gene from only one parent. People with this form of the disorder are carriers of the disease. Most of the time, they do not have symptoms.
Beta thalassemia major is also called Cooley anemia.
Risk factors for thalassemia include:
  • Asian, Chinese, Mediterranean, or African American ethnicityRE

Thalassemia is an inherited blood disorder in which the body makes an abnormal form of hemoglobin. Hemoglobin is the protein molecule in red blood cells that carries oxygen.
The disorder results in excessive destruction of red blood cells, which leads to anemia. Anemia is a condition in which your body doesn’t have enough normal, healthy red blood cells.
Thalassemia is inherited, meaning that at least one of your parents must be a carrier of the disease. It’s caused by either a genetic mutation or a deletion of certain key gene fragments.
Thalassemia minor is a less serious form of the disorder. There are two main forms of thalassemia that are more serious. In alpha thalassemia, at least one of the alpha globin genes has a mutation or abnormality. In beta thalassemia, the beta globin genes are affected.
Each of these forms of thalassemia has different subtypes. The exact form you have will affect the severity of your symptoms and your outlook.

The symptoms of thalassemia can vary. Some of the most common ones include:
Not everyone has visible symptoms of thalassemia. Signs of the disorder also tend to show up later in childhood or adolescence.

Thalassemia occurs when there’s an abnormality or mutation in one of the genes involved in hemoglobin production. You inherit this genetic defect from your parents.
If only one of your parents is a carrier for thalassemia, you may develop a form of the disease known as thalassemia minor. If this occurs, you probably won’t have symptoms, but you’ll be a carrier of the disease. Some people with thalassemia minor do develop minor symptoms.
If both of your parents are carriers of thalassemia, you have a greater chance of inheriting a more serious form of the disease.
According to the Centers for Disease Control and Prevention (CDC), thalassemia is most common in people from Asia, the Middle East, Africa, and Mediterranean countries such as Greece and Turkey.


Keyword Search

Thalassemia Minor

In Thalassemia minor, the hemoglobin genes are inherited during conception, one from the mother (egg) and one from the father (sperm). People with a Thalassemia trait in one gene are known as carriers or are said to have thalassemia minor. The only way to know if you carry the Thalassemia trait is to have a special blood test called hemoglobin electrophoresis which can identify the gene. The carriers of thalassemia minor become anemic or slightly anemic.
If you, your parents, or ancestors are from ‘thalassemia regions’, request a test from your doctor. It is vitally important to identify yourself as a possible carrier of thalassemia minor. Possessing the thalassemia minor trait gives you a 25%, (1 in 4) chance of having a baby with thalassemia major, providing that both parents of the child are both carriers of the disorder. Increased awareness is the key to prevention.

Everything you need to know about thalassemia

Last updated
By Christian Nordqvist
Reviewed by 
Thalassemia is an inherited blood disorder that affects the body's ability to produce hemoglobin and red blood cells.
A person with thalassemia will have too few red blood cells and too little hemoglobin, and the red blood cells may be too small.
The impact can range from mild to severe and life-threatening.
Around 100,000 newborns are delivered each year with severe forms of thalassemia. It is most common with Mediterranean, South Asian, and African ancestry.

Symptoms

[jaundice is symptom of thalassemia]
Jaundice can be a symptom of thalassemia.
The symptoms of thalassemia vary depending on the type of thalassemia.
Symptoms will not show until the age of 6 months in most infants with beta thalassemia and some types of alpha thalassemia. This is because neonates have a different type of hemoglobin, called fetal hemoglobin.
After 6 months "normal" hemoglobin starts replacing the fetal type, and symptoms may begin to appear.
These include:
  • jaundice and pale skin
  • drowsiness and fatigue
  • chest pain
  • cold hands and feet
  • shortness of breath
  • leg cramps
  • rapid heart beat
  • poor feeding
  • delayed growth
  • headaches
  • dizziness and faintness
  • greater susceptibility to infections
Skeletal deformities may result as the body tries to produce more bone marrow.
If there is too much iron, the body will try to absorb more iron to compensate. Iron may also accumulate from blood transfusions. Excessive iron can harm the spleen, heart, and liver.
Patients with hemoglobin H are more likely to develop gallstones and an enlarged spleen.
Untreated, the complications of thalassemia can lead to organ failure.

Treatment

Treatment depends on the type and severity of thalassemia.
[regular blood transfusions may be necessary for people with some types of thalassemia]
Regular blood transfusions may be necessary for people with some types of thalassemia.
Blood transfusions: These can replenish hemoglobin and red blood cell levels. Patients with thalassemia major will need between eight and twelve transfusions a year. Those with less severe thalassemia will need up to eight transfusions each year, or more in times of stress, illness, or infection.
Iron chelation: This involves removing excess iron from the bloodstream. Sometimes blood transfusions can cause iron overload. This can damage the heart and other organs. Patients may be prescribed deferoxamine, a medication that is injected under the skin, or deferasirox, taken by mouth.
Patients who receive blood transfusions and chelation may also need folic acid supplements. These help the red blood cells develop.
Bone marrow, or stem cell, transplant: Bone marrow cells produce red and white blood cells, hemoglobin, and platelets. A transplant from a compatible donor may be an effective treatment, in severe cases.
Surgery: This may be necessary to correct bone abnormalities.
Gene therapy: Scientists are investigating genetic techniques to treat thalassemia. Possibilities include inserting a normal beta-globin gene into the patient's bone marrow, or using drugs to reactivate the genes that produce fetal hemoglobin.

Causes

The protein hemoglobin transports oxygen around the body in blood cells. Bone marrow uses the iron we get from food to make hemoglobin.
In people with thalassemia, the bone marrow does not produce enough healthy hemoglobin or red blood cells. In some types this leads to a lack of oxygen, resulting in anemia and fatigue.
People with mild thalassemia may not require any treatment, but more severe forms will necessitate regular blood transfusions.

Diagnosis

[thalassemia blood test]
Thalassemia is an inherited blood disorder.
Most children with moderate to severe thalassemia receive a diagnosis by the time they are 2 years old.
People with no symptoms may not realize that they are carriers until they have a child with thalassemia.
Blood tests can detect if a person is a carrier or if they have thalassemia.
A complete blood count (CBC): This can check levels of hemoglobin and the level and size of red blood cells.
A reticulocyte count: This measures how fast red blood cells, or reticulocytes, are produced and released by the bone marrow. Reticulocytes usually spend around 2 days in the bloodstream before developing into mature red blood cells. Between 1 and 2 percent of a healthy person's red blood cells are reticulocytes.
Iron: This will help the doctor determine the cause of anemia, whether thalassemia or iron deficiency. In thalassemia, iron deficiency is not the cause.
Genetic testing: DNA analysis will show whether a person has thalassemia or faulty genes.
Prenatal testing: This can show whether a fetus has thalassemia, and how severe it might be.
  • Chorionic villus sampling (CVS): a piece of placenta is removed for testing, usually around the 11th week of pregnancy.
  • Amniocentesis: a small sample of amniotic fluid is taken for testing, usually during the 16th week of pregnancy. Amniotic fluid is the fluid that surrounds the fetus.

Types

Four alpha-globin and two beta-globin protein chains make up hemoglobin. The two main types of thalassemia are alpha and beta.

Alpha thalassemia

In alpha thalassemia, the hemoglobin does not produce enough alpha protein.
To make alpha-globin protein chains we need four genes, two on each chromosome 16. We get two from each parent. If one or more of these genes is missing, alpha thalassemia will result.
The severity of thalassemia depends on how many genes are faulty, or mutated.
One faulty gene: The patient has no symptoms. A healthy person who has a child with symptoms of thalassemia is a carrier. This type is known as alpha thalassemia minima.
Two faulty genes: The patient has mild anemia. It is known as alpha thalassemia minor.
Three faulty genes: The patient has hemoglobin H disease, a type of chronic anemia. They will need regular blood transfusions throughout their life.
Four faulty genes: Alpha thalassemia major is the most severe form of alpha thalassemia. It is known to cause hydrops fetalis, a serious condition in which fluid accumulates in parts of the fetus' body.
A fetus with four mutated genes cannot produce normal hemoglobin and is unlikely to survive, even with blood transfusions.
Alpha thalassemia is common in southern China, Southeast Asia, India, the Middle East, and Africa.

Beta Thalassemia

We need two globin genes to make beta-globin chains, one from each parent. If one or both genes are faulty, beta thalassemia will occur.
Severity depends on how many genes are mutated.
One faulty gene: This is called beta thalassemia minor.
Two faulty genes: There may be moderate or severe symptoms. This is known as thalassemia major. It used to be called Colley's anemia.
Beta thalassemia is more common among people of Mediterranean ancestry. Prevalence is higher in North Africa, West Asia, and the Maldive Islands.

Complications

Various complications can arise.

Iron overload

This may be due to the frequent blood transfusions or the disease itself.
Iron overload raises the risk of hepatitis, (swollen liver), fibrosis (scarring in the liver), and cirrhosis, or progressive liver damage due to scarring.
The endocrine glands produce hormones. The pituitary gland is particularly sensitive to iron overload. Damage may lead to delayed puberty and restricted growth. Later, there may be a higher risk of developing diabetes and either an underactive or overactive thyroid gland.
Iron overload also increases the risk of arrhythmias, or abnormal heart rhythms, and congestive heart failure.

Alloimmunization

Sometimes, a blood transfusion will trigger a reaction where the person's immune system reacts to the new blood and tries to destroy it. It is important to have the exact blood type match to prevent this kind of problem.

Enlarged spleen

The spleen recycles red blood cells. In thalassemia, the red blood cells may have an abnormal shape, making it harder for the spleen to recycle them. The cells accumulate in the spleen, making it grow.
An enlarged spleen can become overactive. It can start to destroy the healthy blood cells the patient receives during transfusions. Sometimes, a patient may need a splenectomy, or surgical removal of the spleen. This is now less common, because removing the spleen can lead to other complications.

Infection

Removing the spleen leads to a higher chance of infection, and regular transfusions increase the risk of contracting a blood-borne disease.

Bone deformities

In some cases, the bone marrow expands, deforming the bone around it, especially the bones of the skull and face. The bone can become brittle, increasing the risk of fracture.

Living with thalassemia

Depending on the type of thalassemia, constant medical care may be necessary to manage the condition effectively. Those receiving transfusions must be sure to follow their transfusion and chelation schedule.
[healthful food]
A healthful diet and exercise are important, but patients should check with their doctors about how much iron-rich food, such as spinach, to consume.
People with thalassemia are advised to:
  • attend all their regular appointments
  • maintain contact with friends and support networks, to help keep a positive attitude
  • follow a healthy diet to maintain good health
  • get a suitable amount of exercise
Some foods, such as spinach or iron-enriched cereals, may have to be avoided, to prevent excessive iron buildup. Patients should discuss dietary and exercise options with their doctor.
The Centers for Disease Control and Prevention (CDC) urge people with thalassemia to keep their vaccinations up to date, to prevent illness.
This is especially important for those who receive transfusions, as they have a higher risk of contracting hepatitis A or B.

Thalassemia and pregnancy

Anyone considering pregnancy should first seek genetic counseling, especially if both partners have or may have thalassemia.
During pregnancy, a woman with thalassemia may have a higher risk of cardiomyopathy and diabetes. There may be fetal growth restriction, too.
The mother should be assessed by a cardiologist or hematologist before and during pregnancy, to minimize problems, especially if she has thalassemia beta minor.
During delivery, continuous fetal monitoring may be recommended.

Outlook

The outlook depends on the type of thalassemia.
A person with the thalassemia trait has a normal life expectancy. However, heart complications arising from beta thalassemia major can make this condition fatal before the age of 30 years.

RELATED COVERAGE

Everything you need to know about anemiaAnemia affects more than 3 million Americans and is the most common blood disorder in the world. It occurs when the body does not have enough red blood cells and is unable to deliver enough oxygen to the cells in the body. This article looks at the three leading causes of anemia and what treatments are available.READ NOW
Everything you need to know about thalassemiaThalassemia is an inherited blood disorder. It inhibits the production of hemoglobin and red blood cells. A person may have alpha or beta thalassemia, and symptoms depend on these types and how many mutated genes a person has inherited. In this article, gain a detailed understanding of the disorder and its treatments.READ NOW
What's to know about neutropenia?Neutropenia describes a significant reduction in a type of white blood cell called neutrophils. Produced in bone marrow, these are an essential first line of defense against infections. Here, learn more about types, causes, symptoms, and treatments of neutropenia, which is common in people receiving chemotherapy.READ NOW
What's to know about low platelet count?A low platelet count is a blood disorder, but it is not always serious. We take a look at what platelets are and their role within the body. We also discuss the many possible causes of a low count, including underlying conditions and common medications. Read on for information about symptoms, treatment, and diagnosis.READ NOW
All you need to know about thick bloodA look thick blood (hypercoagulability) a condition that interferes with the normal clotting process, causing excessive blood clotting. Learn more here.READ NOW
Leukemia: What you need to knowLeukemia is a cancer caused by an overproduction of damaged white blood cells. It is common in children, but leukemia most often occurs in adults older than 55. The outlook depends on the type of the disease. Find out more about these types, as well as early symptoms, risk factors, and ways to manage this illness.READ NOW
BLOOD / HEMATOLOGY 
GENETICS

Additional information

    Article last updated by Adam Felman on Wed 10 January 2018.

    Visit our Blood / Hematology category page for the latest news on this subject, or sign up to our newsletter to receive the latest updates on Blood / Hematology.

    All references are available in the References tab.

References

Citations

Recommended Related News











Comments

Post a Comment