Thalassaemia is a group of inherited disorders that affect the amount of haemoglobin a person produces. Haemoglobin refers to a family of compounds all made up of haem (an iron-containing complex), and various globins (protein chains that surround the haem complex). Haemoglobin (Hb) molecules are found in all red blood cells, and are the reason for their red colour. They bind oxygen in the lungs, carry it through the bloodstream, and release it to the body’s tissues.
This test measures the type and relative amounts of haemoglobins present in the red blood cells. Haemoglobin A, composed of both alpha and beta globin, is the major normal type of haemoglobin found in adults. A greater percentage of HbA2 and/or HbF is usually seen in beta thalassaemia trait. HbH may be seen in alpha thalassaemia, but only when at two of the four alpha genes are deleted or mutated.