Thalassemia trait (Mediterranean anemia carrier)

Causes and who gets it

Hemoglobin is the protein in red blood cells that carries oxygen. It is made of chains called alpha and beta. In thalassemia, the body makes less of one of these chains. The condition is passed down through genes from your mother and father. It is not acquired later in life, and you cannot catch it from someone.

• Beta thalassemia: Everyone has two beta genes, one from their mother and one from their father. If only one is changed, the person is a carrier. If both are changed, thalassemia major or thalassemia intermedia develops.
• Alpha thalassemia: There are four alpha genes. Missing one gene usually causes no signs at all (silent carrier). Missing two genes may cause mild anemia. Missing three or four genes causes disease.

Thalassemia major (Mediterranean anemia) is a severe disease that starts in infancy and needs regular blood transfusions. Thalassemia intermedia is milder; transfusions are needed less often and later in life.

According to documents from the Turkish Ministry of Health (Sağlık Bakanlığı), about 2.1% of people in Türkiye carry beta thalassemia, ranging from 0.6% to 13% depending on the region. It is more common in the western and southern regions. The Ministry lists the high rate of marriages between relatives among the reasons the disease is common in the country. The more serious carrier type of alpha thalassemia (alpha zero) is more common in families of southern Mediterranean origin, which includes Türkiye.

Symptoms

Most carriers have no complaints at all. The condition is often noticed in a blood count done for another reason or during premarital screening. Some people may feel tired or look pale because of mild anemia. Carrier status does not progress over time into thalassemia disease.

The anemia in carriers is usually mild. If tiredness, shortness of breath, dizziness or headache is marked or getting worse, look into the cause with your doctor. Do not put these down to being a carrier alone.

Diagnosis and tests

Carrier status can be found with simple blood tests:

• Complete blood count (CBC): MCV (the average size of a red blood cell) and MCH (the amount of hemoglobin per red blood cell) are low. The red blood cell count (RBC) is normal or high. MCV is also low in iron deficiency, but the red blood cell count is usually lower.
• Iron tests: In iron deficiency, ferritin (the body’s iron store) is low. In carriers, ferritin is not low unless there is also iron deficiency.
• Hemoglobin electrophoresis or HPLC: These tests separate and measure the types of hemoglobin in the blood. In beta thalassemia trait, the share of a minor hemoglobin type called HbA2 is raised; in the most common type it is roughly between 3.5% and 8%.
• DNA test: In alpha thalassemia trait, HbA2 is normal, so a genetic test may be needed for diagnosis. It is also used to find the exact type of gene change when both partners are carriers.

Some calculations made from the blood count give clues, but they cannot make the diagnosis on their own. If there is iron deficiency at the same time, HbA2 may come out normal and carrier status may be missed.

Treatment approach

Carrier status needs no treatment; no medicine or blood transfusion is needed. The mild anemia in carriers is not caused by iron deficiency. So iron tablets should be used only if tests have separately shown iron deficiency. Taking iron when your body already has enough can be harmful. The Ministry of Health also points out that beta thalassemia carriers may be wrongly thought to have iron deficiency and treated for it for years.

In thalassemia major, treatment includes regular blood transfusions, medicines that remove the extra iron that builds up in the body from transfusions (chelation therapy), and, for suitable patients, a bone marrow (stem cell) transplant. These treatments are planned at specialist centers.

Everyday life and follow-up

Carriers can live a normal life without health problems caused by this condition. Carrier status is not contagious and is not a barrier to marriage.

• Keep your test result. Tell any new doctor that you are a carrier, especially when anemia is being assessed and during pregnancy.
• Your mother, father, brothers and sisters, aunts, uncles and cousins may also be carriers. They are advised to get tested before having children.
• If you are thinking of having children, your partner also needs to be tested.

Pregnancy, children and special situations

Pregnancy: If you are pregnant or planning a pregnancy, tell your doctor as early as possible that you are a carrier. If your partner has not been tested, they need to be. If you are both carriers, a sample taken during pregnancy from the placenta or from the fluid around the baby (amniotic fluid) can show whether the baby is affected. For this process to go smoothly, it is advised that the gene changes in both parents are identified before pregnancy. If both partners are alpha zero carriers, the baby may develop alpha thalassemia major; this can cause severe anemia in the baby and pregnancy loss, and it also carries risks for the mother. If you are offered iron during pregnancy, mention that you are a carrier; your iron levels should be checked.

Children: If only one partner is a carrier, the child will not have the disease, but each child has a 50% chance of being a carrier. In children, too, a low MCV can be caused either by iron deficiency or by carrier status; the doctor tells them apart with tests. Babies with thalassemia major look healthy at birth; signs usually appear after the first few months. If you and your partner are carriers, talk to your doctor about testing your other children.

In Türkiye

Türkiye runs a Hemoglobinopathy Control Program based on Law No. 3960 on Fighting Hereditary Blood Diseases of 1993 and a regulation published in 2002. According to Ministry documents, premarital screening was first carried out in 41 provinces considered at risk and has covered all 81 provinces since 2018. In the provinces where the program started first, the number of babies born with a hemoglobinopathy (an inherited hemoglobin disorder) is reported to have fallen from 300 to below 100.

• When you go to your family doctor for the premarital health report, you are given information and sign a consent form.
• Blood is taken from the male partner first. If he is found to be a carrier or the result is uncertain, the female partner is also tested. In special cases both partners may be tested together.
• A blood count and HPLC or capillary electrophoresis methods are used.
• If both partners turn out to be carriers, the marriage is not blocked. The couple is referred to a hematologist (or to an internal medicine specialist if there is none in the province) and is given genetic counseling before having children.

The aim of screening is not to prevent marriage but to identify carrier couples in advance and help them have healthy babies. Genetic testing of embryos together with IVF is also among the options.

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