MARCH 2024 — BIOLOGY STD 12 Science — Question

→ Gene therapy is a collection of methods that allows correction of a gene defect that has been diagnosed in a child/embryo.
→ Here by using DNA medicinal protein is produce which correct or treat the mutated Gene.
→ Here genes are inserted into a person's cells and tissues to treat a disease.
→ Correction of a genetic defect involves delivery of a normal gene in to the individual or embryo to take over the function of and compensate for the non-functional gene.
→Example - Adenosine deaminase deficiency
→ 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, 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.