Thalassaemia is an inherited disorder of the red blood cells. These cells contain the hemoglobin molecule, which is responsible for binding oxygen from the air we breathe and carrying it to the tissues where energy is released.
In Thalassaemia one of the components of the hemoglobin molecule is inadequately produced or not produced at all. If there is lack of α chain production then the result is known as α thalassemia. If the component that is lacking is the α chain, then the resulting condition is α thalassemia.
The reason for the inadequate or non- production of these components is a change in the genetic code (mutation), in that part of the DNA, which is the template for the production of the protein. The mutation or altered gene cannot initiate the process, which hamper the production of necessary amount of protein.
Genes, sections of DNA responsible for a protein, are carried on chromosomes and each individual has a pair: one chromosome from each parent.
A mutation may exist on one chromosome of a pair, but not on the other. The protein produced by the one, healthy, and chromosome is enough to keep the individual well, even though his/her red cells are smaller than normal. Such an individual is known as a carrier (or heterozygote) who can only be detected by special blood tests. A carrier may give his/her offspring either the healthy chromosome or the one bearing the mutation.
Severe thalassaemia (Thalassemia Major) will result if a child inherits the abnormal (mutation bearing) chromosome from both parents. In other words both parents must be carriers if a major Thalassaemia disorder is present in the child. This situation is known as homozygous thalassemia.