What is Thalassemia? Is it Anemia?
Thalassemia is a group of inherited anemia disorders caused by autosomal recessive genes. It results from genetic mutations in the globin gene that controls the production of globin chains, which are essential components of hemoglobin in red blood cells. This causes red blood cells to have a shorter lifespan than normal, leading to anemia, which reduces oxygen delivery to various organs in the body. These genes are inherited half from the father and half from the mother. The abnormalities can vary, including reduced globin production or abnormal globin chains. The severity depends on the type and number of defective genes.
Thalassemia Carriers in Thai People
In Thailand, a large portion of the population are thalassemia carriers, divided by type as follows:
- 20-30% are alpha thalassemia carriers
- 13% are hemoglobin E carriers
- 9% are beta thalassemia carriers
How Many Types of Thalassemia Are There?
Thalassemia is divided into two main types: alpha thalassemia and beta thalassemia.
1. What is Alpha Thalassemia?
Alpha thalassemia results from mutations in the genes controlling the production of alpha globin chains, located on chromosome 16. There are 4 alpha globin gene loci. The severity depends on the type and number of defective genes, classified as follows:
- Alpha thalassemia trait (carrier)
If 1-2 gene loci are defective, it is called thalassemia trait or carrier status. This is not considered a disease, so there are no symptoms and no treatment is needed. However, it can be passed on to offspring. Blood tests usually show smaller red blood cells.
- Hb H disease
If 3 gene loci are defective, it is called Hb H disease, a form of thalassemia. Patients have anemia, but it is usually not severe and does not require regular blood transfusions. However, acute hemolysis may occur during fever or infection, and iron overload can accumulate in the body. Regular medical follow-up is recommended.
- Hydrops fetalis
If all 4 gene loci are defective, it is called Hb Bart’s hydrops fetalis, a condition where the fetus has generalized edema. The fetus usually dies in utero or shortly after birth. This is the most severe form of thalassemia. Couples planning to have children should undergo screening to ensure the baby is not at risk for this condition.
2. What is Beta Thalassemia?
Beta thalassemia results from mutations in the genes controlling the production of beta globin chains, located on chromosome 11. There are 2 beta globin gene loci. The severity depends on the type and number of defective genes, classified as follows:
- Beta thalassemia minor (carrier)
If 1 gene locus is defective, it is called thalassemia trait or carrier status. This is not considered a disease, so there are no symptoms and no treatment is needed. However, it can be passed on to offspring. Blood tests usually show smaller red blood cells.
- Beta thalassemia intermedia (mild form)
If 2 gene loci are defective in a mild form, patients have anemia but it is usually not severe. Most do not require regular blood transfusions but may develop iron overload. Regular medical follow-up is recommended. (Homozygous hemoglobin E is not considered a disease and does not require treatment, similar to thalassemia carriers.)
- Beta thalassemia major (severe form)
If 2 gene loci are defective in a severe form, patients have severe anemia, enlarged liver and spleen, facial deformities, growth retardation, osteoporosis, bloodstream infections, gallstones, extramedullary hematopoiesis, pulmonary hypertension, chronic leg ulcers, and iron overload affecting the heart, liver, and endocrine system. Patients require regular monthly blood transfusions and close monitoring for iron overload. Couples planning to have children should undergo screening to ensure the baby is not at risk for this condition.
How to Diagnose Thalassemia
Thalassemia diagnosis can be done through blood tests, which include:
1. CBC (Complete Blood Count) to check for anemia with small red blood cells
2. Hb typing to detect beta thalassemia, beta thalassemia carriers, and alpha thalassemia
3. PCR for alpha thalassemia to detect alpha thalassemia carriers
How to Treat Thalassemia
1. Blood transfusions for severe thalassemia or when medically indicated
2. Taking folic acid supplements to help produce red blood cells
3. Monitoring blood levels and iron accumulation every 3-6 months to manage treatment appropriately
4. Taking or injecting iron chelation drugs when indicated (serum ferritin >800 ng/mL in patients not receiving regular transfusions or >1,000 ng/mL in patients receiving regular transfusions)
5. Screening for complications from the disease and iron overload to manage and treat complications
Planning for Children if You Are a Thalassemia Carrier
Carriers can pass defective genes to their children. Therefore, couples planning to have children should be tested to see if they are carriers. If both partners are carriers of the same type of thalassemia, there is a 25% chance their child will have thalassemia.
Therefore, once pregnant, it is important to register for prenatal care and consult a doctor promptly to diagnose the fetus at the appropriate gestational age to assess the risk of inheriting recessive genes and developing thalassemia. Couples may also choose assisted reproductive techniques to screen embryos before pregnancy, which increases safety for the fetus.
