Question : How is gene therapy useful for diagnosis for various diseas

1.	Question : How is gene therapy useful for diagnosis for various diseases ?
Answer» Solution :Gene therapy is useful for treatment of a hereditary disease. In which that allows correction of a gene defect that has been diagnosed in a child/embryo. Genes are inserted into a person.s cells and tissues to treat a disease. The first clinical gene therapy was given in 1990 to a 4 year old girl with adenosine deaminase (ADA) deficiency. This enzyme is crucial for the immune system to function. The disorder is caused due to the deletion of the gene for adenosine deaminase. In some children ADA deficiency can be cured by bone MARROW transplantation, in others it can be TREATED by enzyme replacement therapy in which functional ADA is given to the patient by injection. But the problem with both of these approaches that they are not completely curative. As a first step towards gene therapy, lymphocytes from the blood of the patient are grown in a culture OUTSIDE the body. A functional ADA-cDNA (using a retroviral vector) is then introduced into these lymphocytes, which are subsequently returned to the patient. However as these cells are not immortal. So the patient requires periodic infusion of such GENETICALLY engineered lymphocytes. However if the gene isolate from marrow cells producing ADA is introduced into cells at early embryonic stages, it could be a permanent cure.

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