Thalassemia is an inherited blood disorder caused by defects in the synthesis of one or more of the hemoglobin chains. There are two main types – alpha and beta thalassemia. Signs and symptoms vary but may include mild to severe anemia, paleness, fatigue, yellow discoloration of skin (jaundice), and bone problems.
Both thalassemias are inherited in an autosomal recessive manner. Silent carriers of alpha thalassemia and persons with alpha or beta thalassemia trait are asymptomatic and require no treatment.
Alpha (α) thalassemia is caused by mutations in the HBA1 and/or HBA2 genes, which leads to reduction or absent synthesis of alpha globin chains. Alpha thalassemia major with hemoglobin Bart’s usually results in fatal hydrops fetalis. Alpha thalassemia intermedia, or hemoglobin H disease, causes hemolytic anemia.
Beta (β) thalassemia is caused by mutations in the HBB gene, which leads to reduction or absent synthesis of beta globin chains. Beta thalassemia major causes hemolytic anemia, poor growth, and skeletal abnormalities during infancy. Affected children will require regular lifelong blood transfusions. Beta thalassemia intermedia is less severe than beta thalassemia major and may require episodic blood transfusions.
If both parents are same type of thalassemia carrier, there is a 25% risk that the offspring have the recessive trait in phenotype.
Indications for testing:
✓ Differential diagnosis of microcytic anemia
✓ Detection of prospective parents at risk for a pregnancy with thalassemia
- Whole blood 3ml EDTA x2, >1ml SSTx1 (for Ferritin test)
Testing Scope :
– α-thalassemia (αα/–) of SEA, Philippine and Thailand type
– α-thalassemia (αα/-α) ) α3.7,α4.2 deletion and HbCS (c.427T>C) ,HbQS(c.377T>C)
– 20 most common β-thalassemia mutations