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Can there be more treatment options for thalassaemia?

Q: Thalassaemia is a killing blood disorder, which kills the entire family of the patient. Presently the treatment is only through blood transfusion, chelation through out life till the patient lives. The most prevalent is beta thalassaemia. I like to propose a method of treatment of thalassaemia. We know that beta thalassaemia is due to non-existence of beta chain in blood. As such the alpha chain damages red blood corpuscles. There are so many varieties of beneficial microbes present in our body/ blood vessel / stomach, which support our body metabolism as well as health. I request that research may be conducted to find those microbes which can cause secretion of human beta chain in blood vessel or the existing microbes are modified to generate human beta chain in blood vessel. I know that this will require some structured genetic engineering in which India can really show the path to obviate requirement of blood transfusion. Blood transfusion is not only a very costly proposition for the poor people of India but is associated with large number of complications, still is not a preferred solution. Please advise.

A:As you have mentioned, thalassaemias are a group of genetic diseases caused by the production of abnormal haemoglobin (Hb). A molecule of Hb is made up of a haeme part that contains iron and 4 globin chains. The globin chains are – 2 alpha chains (a) and 2 non-alpha chains (b, d or g). The adult haemoglobin (Hb A) has 2a & 2b-chains, fetal Hb (Hb F) has 2a & 2g-chains and Hb A2 has 2a & 2d-chains. The a-chain is made up of 141 amino acids and b-chain of 146 amino acids. The production of these globin chains is controlled by genes (called globin genes) present on 2 different chromosomes (chromosome 16 for a-globin genes and chromosome 11 for non-a globin genes). There are 4 a-globin genes controlling the production of 2 a-chains while 2 b-globin genes produce 2 b-chains. In b-thalassaemia, the production of b-chain is abnormal while in a-thalassaemia it is the a-chain production that is affected. If both b-globin genes are affected (mutation), it results in b-thalassaemia major. Genes control the production of these chains by adding the amino acids one at a time and then stopping when the chain is ready. Then these chains are joined together and later linked to the haeme molecule. This is a very complex process in which different parts of the genes regulate different stages. The expression of the alpha and non-alpha genes is closely balanced by an unknown mechanism. Balanced gene expression is required for normal red cell function. No microbe can replicate this and we cannot use them to synthesise the missing chain. What is being tried instead is inserting a normal gene (to replace the ‘bad’ gene) taking help of viruses, which have the capacity to bind to human DNA and inserting a part of their own DNA. So first we introduce a normal globin gene into a virus and then try and use that virus to insert that normal gene into the DNA of a thalassaemia patient. This, however, poses many challenges. We want the gene to be precisely inserted on chromosome 16 (or 11 as the case may be). Then we want that this gene should produce normal globin chains only in those bone marrow cells that produce haemoglobin (not cells of the liver or heart or the skin). Such precise insertion of genes and control of their expression still eludes us. The only definitive therapy currently available is stem cell transplant using allogeneic haematopoietic cells. But this has it's own problems.


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