Question

What is gene therapy? Illustrate using the example of adenosine deaminase deficiency.

Hint:

While periodic infusion of genetically engineered lymphocytes is a treatment, a permanent cure is possible only if the gene is introduced into marrow cells at early embryonic stages.

Answer 1

Step 1: Gene therapy involves the delivery of a normal gene into the individual or embryo to take over the function of and compensate for the non-functional gene.
Step 2: In the first clinical case (1990), a 4-year-old girl with ADA deficiency was treated. ADA is crucial for the immune system to function.
Step 3: Lymphocytes from the patient's blood were grown in culture, and a functional ADA cDNA was introduced into them using a retroviral vector. These cells were then returned to the patient.