Thalassaemia is an inherited blood disorder that disrupts the body’s ability to produce healthy red blood cells and hemoglobin, the protein responsible for carrying oxygen throughout your body. This condition affects millions of people worldwide, particularly those with ancestral roots in regions where malaria has historically been common, and while it ranges from mild forms that may cause no symptoms at all to severe types requiring lifelong medical care, advances in treatment have significantly improved the lives of those living with this genetic condition.

Understanding How Common Thalassaemia Is

Thalassaemia is one of the most widespread inherited blood conditions globally. According to recent data, approximately 280 million people around the world were affected by thalassaemia in 2015, making it a significant health concern in many communities^[7]. The condition is slightly more common in males than females, though the difference is minimal^[7]. Worldwide, there are approximately 350,000 births per year with serious hemoglobinopathies, which include thalassaemia and related blood disorders^[8].

The geographic distribution of thalassaemia is quite specific. The condition primarily affects people from certain parts of the world, particularly those with ancestral links to regions where malaria has been prevalent. Alpha thalassaemia, which affects the alpha globin chains of hemoglobin, is most commonly found in people from Southeast Asia, Malaysia, southern China, the Middle East, and in those of African descent^[5]. Beta thalassaemia, which affects the beta globin chains, is more concentrated in Mediterranean countries, though it can also affect people of Chinese, other Asian, and African American backgrounds^[5].

In the United States, the incidence of thalassaemia has increased in recent years, largely due to immigration patterns. As people from regions where thalassaemia is common have moved to North America, the number of cases has grown, particularly among immigrants from Southeast Asia^[8]. The World Health Organization estimates that between five and seven percent of the world’s population carries a thalassaemia trait, meaning they have a genetic change that could be passed on to their children but may not experience symptoms themselves^[9].

What Causes Thalassaemia

Thalassaemia is caused by changes, or mutations, in the genes that control the production of hemoglobin. Hemoglobin is a complex protein found in red blood cells that consists of four protein chains: two alpha globin chains and two beta globin chains^[1]. Each of these chains is built according to genetic instructions, or genes, that are passed down from your parents to you. Think of these genes as detailed blueprints that tell your body exactly how to construct each part of the hemoglobin protein.

The alpha globin protein chains are controlled by four genes in total, with two genes inherited from each parent. The beta globin protein chains, on the other hand, are controlled by just two genes, one from each parent^[1]. When any of these genes are defective or missing entirely, the body cannot produce hemoglobin properly, resulting in thalassaemia. The specific type of thalassaemia a person has depends on whether the defect affects the alpha or beta chain, and the severity of the condition depends on how many genes are affected.

This is a genetic disorder, meaning it is inherited from biological parents. It is not something you can catch from others or develop later in life due to lifestyle choices^[2]. The condition follows an autosomal recessive pattern of inheritance in most cases, which means that a child must receive a faulty gene from both parents to develop the more serious forms of thalassaemia^[4].

Who Is at Higher Risk

The gene mutations that cause thalassaemia originally arose in human populations as a form of partial protection against malaria. This explains why thalassaemia is most common in people whose ancestors came from parts of the world where malaria is or was prevalent^[1]. These regions include Africa, Southern Europe, and West, South, and East Asia. If your family heritage traces back to Mediterranean countries such as Greece, Italy, or Cyprus, or to Middle Eastern nations, Southeast Asian countries, or parts of Africa, you have a higher likelihood of carrying the thalassaemia trait or having the condition.

The distribution of thalassaemia types varies by region. Alpha thalassaemia is particularly concentrated in Southeast Asia, Malaysia, southern China, the Middle East, and among people of African descent^[5]. Beta thalassaemia is more commonly found in people of Mediterranean origin, though Chinese, other Asians, and African Americans can also be affected to a lesser extent^[5].

Beyond ancestry, family history plays a crucial role in determining risk. Because thalassaemia is inherited, having parents, siblings, or other close relatives with the condition or who are known carriers significantly increases your risk^[2]. If you have a family history of thalassaemia and are considering having children, genetic counseling can help you understand the likelihood of passing the condition to your offspring.

Recognizing the Symptoms

The symptoms of thalassaemia can vary dramatically depending on which type you have and how severe it is. Some people with mild forms, often called thalassaemia trait or minor, may have no symptoms at all and may not even know they have the condition unless they undergo specific blood testing^[3]. These individuals have small red blood cells but typically do not experience health problems.

People with more severe forms of thalassaemia, however, can experience significant symptoms related to anemia, which is a condition where the body doesn’t have enough healthy red blood cells to carry adequate oxygen to tissues. The most common symptoms of anemia in thalassaemia include feeling extremely tired or fatigued, which can interfere with daily activities and make even simple tasks feel exhausting^[1]. This fatigue occurs because the body’s cells are not receiving enough oxygen to produce the energy they need to function properly.

Additional symptoms include weakness, which may make it difficult to perform physical activities or maintain normal routines. Many people with thalassaemia experience shortness of breath, particularly during physical exertion, as the body struggles to deliver oxygen where it’s needed^[3]. Feeling cold is another common symptom, as is dizziness, which can affect balance and concentration^[1]. Pale skin is often noticeable in people with thalassaemia because there are fewer red blood cells circulating in the body.

In more severe cases, particularly in children with beta thalassaemia major, additional symptoms can develop. These may include yellowing of the skin and eyes, a condition called jaundice, which occurs when red blood cells break down too quickly^[2]. Dark-colored urine is another sign of this breakdown process. Some children may experience changes or problems with their facial bones, giving the face a distinctive appearance, and may have slow growth or delayed development compared to their peers^[2]. Swelling of the stomach area, known as the abdomen, can occur due to an enlarged spleen or liver, and poor appetite is common^[2].

People with severe thalassaemia may also experience headaches, leg cramps, difficulty concentrating, and a fast heartbeat as the heart works harder to compensate for the reduced oxygen-carrying capacity of the blood^[3]. Children born with beta thalassaemia major, also known as Cooley anemia, are typically normal at birth but begin to show symptoms during the first year of life as fetal hemoglobin is replaced by adult hemoglobin^[5].

Preventing Thalassaemia

Because thalassaemia is an inherited genetic condition, it cannot be prevented in the traditional sense through lifestyle changes or vaccinations. However, there are important steps that individuals and couples can take to understand their risks and make informed decisions about family planning.

The most important preventive measure is genetic testing and counseling before starting a family. It is suggested that all couples be tested for their thalassaemia carrier status before becoming pregnant^[9]. This is particularly crucial for individuals with ancestral links to regions where thalassaemia is common. Testing can reveal whether one or both partners carry the genetic changes that cause thalassaemia, which helps couples understand the likelihood of having a child with the condition.

If both partners are found to be carriers, genetic counselors can explain the risks in detail and discuss the available options. These may include prenatal testing during pregnancy to determine whether the fetus has inherited thalassaemia. Prenatal testing options include chorionic villus sampling, which involves removing a small piece of the placenta, typically around the 11th week of pregnancy, and amniocentesis, which involves testing a sample of the fluid surrounding the baby in the womb, usually done around the 16th week of pregnancy^[10]. These tests can help expectant parents prepare for the care their child may need if born with thalassaemia.

For communities where thalassaemia is particularly common, screening programs have been established to identify carriers and provide education about the condition. These programs aim to reduce the number of children born with severe forms of thalassaemia by ensuring that couples are aware of their carrier status before conceiving. In England, screening for thalassaemia is offered to all pregnant women to check if there’s a risk of a child being born with the condition^[6]. Some types of thalassaemia may also be detected during the newborn blood spot test, commonly known as the heel prick test^[6].

How Thalassaemia Affects the Body

To understand how thalassaemia affects the body, it’s helpful to first understand what happens in healthy red blood cells. Red blood cells are responsible for transporting oxygen from the lungs to every cell in the body. This vital function depends on hemoglobin, a protein that acts like a delivery truck for oxygen. Hemoglobin is made of two different parts: alpha globin and beta globin chains^[3]. In a healthy person, these chains are produced in balanced amounts and combine to form normal hemoglobin.

In thalassaemia, genetic defects mean that either the alpha or beta globin chains are not produced in sufficient quantities or are absent altogether^[3]. When this happens, the body cannot make enough normal hemoglobin. Without adequate hemoglobin, red blood cells cannot form properly and cannot carry enough oxygen to meet the body’s needs. This leads to anemia, where there are fewer healthy red blood cells in circulation than normal.

The severity of thalassaemia depends on how many genes are affected. In alpha thalassaemia, there are four genes controlling alpha globin production. If only one gene is defective or missing, a person typically has no symptoms, a condition called alpha thalassaemia minima^[1]. If two genes are affected, symptoms are usually mild, known as alpha thalassaemia minor. When three genes are defective or missing, the person develops Hemoglobin H disease with moderate to severe symptoms. If all four genes are affected, this usually results in death, often before birth, as the condition is incompatible with life^[1].

In beta thalassaemia, there are only two genes controlling beta globin production, one from each parent. A person who inherits one defective gene from one parent has beta thalassaemia minor or trait, which causes mild or no symptoms^[4]. If both genes are defective, the person develops beta thalassaemia major, the most severe form, which requires lifelong treatment including regular blood transfusions to maintain adequate hemoglobin levels.

When the body doesn’t produce enough of one type of globin chain, the other type may accumulate. These excess chains can damage red blood cells, causing them to be destroyed prematurely. This process is called ineffective erythropoiesis, meaning the bone marrow produces red blood cells, but they are destroyed before they can fulfill their function^[4]. The rapid breakdown of red blood cells releases iron, which can accumulate in organs like the heart, liver, and endocrine glands, potentially causing serious damage over time.

The bone marrow, which is the spongy tissue inside bones where blood cells are made, responds to the shortage of healthy red blood cells by working harder to produce more. This can cause the bones to expand and may lead to bone deformities, particularly in the face and skull^[2]. The spleen, an organ that normally filters old blood cells, may become enlarged as it works overtime to remove the abnormal red blood cells from circulation. An enlarged spleen can trap not only red blood cells but also platelets and white blood cells, potentially leading to other complications.