Question

How does the gene therapy help in the people suffering from ADA?

Answer 1

Three types of therapy are available for the treatment of ADA deficiency -

• Bone marrow transplant (BMT): replaces defective immune cells with healthy immune cells from a donor
  
• Enzyme replacement therapy (ERT): replaces the missing ADA enzyme and allows the immune system to function properly.
  
• Gene therapy: experimental therapy that replaces defective genes with genetically modified ones, restoring or increasing levels of ADA. 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 a 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.