Whether you inherit alpha- or beta-thalassemia depends on which genes are affected. The number of affected genes can determine the subtype of alpha- or beta-thalassemia and the severity of your symptoms.
Thalassemias are a group of inherited blood conditions that result from problems within the genes that produce hemoglobin.
Hemoglobin is the main component of your red blood cells. It’s responsible for carrying oxygen. Deletions or mutations in the genes that make hemoglobin mean that your red blood cells might form improperly, burst easily, or be unable to carry an adequate amount of oxygen.
Different types of hemoglobin gene deletions and mutations result in different types of thalassemia, ranging from mild to very serious. But people with any form of thalassemia often have a low red blood cell count (anemia) and small red blood cells persistently throughout their lives.
Usually, you inherit a total of four α globin genes and two β globin genes from your parents. Together, they produce nearly all the hemoglobin in your red blood cells.
People with alpha-thalassemia have a deletion of one or more of their α globin-producing genes.
| Genes (two from each parent) | Condition | Description |
|---|---|---|
| α α / α – (1 missing) | alpha-thalassemia carrier | You’re a silent carrier with no significant symptoms. Your other α globin genes can still produce enough healthy hemoglobin. |
| α α / – – α – / α – (2 missing) | alpha-thalassemia trait | Mild symptoms can include anemia and slightly smaller red blood cells. |
| α – / – – (3 missing) | hemoglobin H (HbH) disease | You may have moderate anemia and be prone to hemolysis, especially when sick or exposed to certain medicines or chemicals. As you age, you might develop jaundice, liver and spleen enlargement, and gallbladder or bone problems. |
| – – / – – (4 missing) | alpha-thalassemia major | The body’s inability to make effective hemoglobin usually causes death before birth due to severe fetal anemia and hydrops fetalis. |
You have two β globin genes — one from each parent. Mutations in these genes cause beta-thalassemia.
Some people have a mutation that reduces the amount of β globin they produce (β+), while others have a mutation that prevents their body from making any β globin (β0).
| Genes (one from each parent) | Condition | Description |
|---|---|---|
| β / β+ β / β0 β+ / β+ | beta-thalassemia minor | You may have mild anemia and small red blood cells. |
| β+ / β+ β+ / β0 | beta-thalassemia intermedia | β globin production is reduced. Symptoms are less severe. |
| β0 / β0 β+ / β0 | beta-thalassemia major | Your body can’t produce enough β globin. Symptoms are usually more severe and tend to appear earlier, often by 2 years old. |
Symptoms of beta-thalassemia intermedia or major include:
- moderate to severe anemia
- pale skin
- jaundice
- restricted growth
- bone problems
- enlarged liver and spleen
- gallbladder problems
- pulmonary hypertension
- increased chance of infections
You may need frequent blood transfusions, especially in beta-thalassemia major. This can cause iron overload and heart, liver, and endocrine problems.
Thalassemia mutations are more common in certain populations, particularly those of African, Southeast Asian, Middle Eastern, or Mediterranean descent. These areas have historically had a high incidence of malaria, and thalassemia mutations may have been protective against this infection.
If thalassemia or thalassemia trait runs in your family, consult a doctor if you begin planning a family. Since thalassemia trait doesn’t typically cause serious symptoms, you may not realize you’re a carrier. When two carriers have a baby, there’s a chance that their child will have more severe symptoms.
Many symptoms of the more severe forms of alpha- and beta-thalassemia are quite similar. They stem from the complications of anemia, hemolysis, and excess iron.
Alpha-thalassemia major is usually fatal before birth. Children with beta-thalassemia major appear well at birth but develop symptoms by about 2 years old.
People with beta-thalassemia major generally require more frequent blood transfusions than those with HbH alpha-thalassemia, and their condition is usually more severe.
Treatment for either kind of thalassemia depends on the severity of your symptoms.
If you’re a silent carrier, you usually won’t need any treatment. You may have mild anemia with smaller red blood cells, but you typically won’t require iron supplementation.
With moderate forms of the condition, like beta-thalassemia intermedia, you may need to take medications to support red blood cell production and manage iron overload. You’ll require close monitoring by a hematologist and primary care physician. As you age, you may also need:
- blood transfusions
- iron chelation
- surgery to remove the spleen or gallbladder
People with severe thalassemia, like beta-thalassemia major, may require treatment earlier in life. In addition to the above treatments, other treatments may include:
- frequent blood tests
- close monitoring of heart and liver function
- stem cell transplant
Alpha-thalassemia major is usually life threatening before birth. If a doctor identifies it early, they might discuss experimental therapies like intrauterine blood transfusions followed by stem cell transplantation.
The following are some commonly asked questions about alpha- and beta-thalassemia.
Is alpha-thalassemia more severe?
Both alpha- and beta-thalassemia minor are generally mild.
Alpha-thalassemia major is more severe than the beta form, usually causing death before birth. But beta-thalassemia major can also be life threatening and is usually more severe than the HbH form of alpha-thalassemia.
Are alpha- and beta-thalassemia dominant or recessive?
Both alpha- and beta-thalassemia usually follow an
Which is more common, alpha- or beta-thalassemia?
The prevalence of thalassemia varies by region, but experts estimate that up to 5% of the world’s population carry a gene for alpha-thalassemia, while about 1.5% carry a gene for beta-thalassemia.
Can you have both alpha- and beta-thalassemia?
It’s possible to inherit both α and β globin gene mutations from your parents. You can also co-inherit thalassemia mutations with other hemoglobin gene problems, such as sickle cell trait.
Interestingly, people with beta-thalassemia major who also inherit an α globin gene deletion may have
How do I know if I have the gene for alpha- or beta-thalassemia?
To diagnose thalassemia, a doctor can review blood tests such as a complete blood count and smear, iron levels, and hemoglobin electrophoresis. In some cases, they may recommend genetic testing to determine your status.
Thalassemias result from mutations in the genes responsible for making hemoglobin, a protein that allows your blood to carry oxygen. As different genes are responsible for creating α globin and β globin chains, different mutations result in either alpha- or beta-thalassemia.
Several genetic combinations are possible, which determine the type of thalassemia and the severity of your symptoms. But all types typically cause some degree of anemia with other complications.
Babies who inherit alpha-thalassemia major often die before birth, though screening and experimental new therapies offer hope to affected families. For other forms of alpha- or beta-thalassemia, expert monitoring and treatment can help manage the symptoms and reduce complications.
