Who was the first patient who was given gene therapy ? Why was the given treatment recurrent in nature ?

Explanation

Ashanti desilva a 4 year girl was treated for the first time. She was suffering from 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, 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.
Through cloning, several ADA gene copies are produced
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The Viral genes are replaced by ADA genes in the modified retrovirus
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From the bone marrow of the patient, lympho cytes are obtained and are cultured invitro.
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These lymphocytes are infected by recombinant retroviruses
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ADA gene is expressed in this infected lymphocyte
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Infected lymphocytes are injected back into patient.s body
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ADA gene is expressed, and the deficiency is partially corrected.