Question

The genetic defect, adenosine deaminase (ADA) deficiency, may be cured permanently by

• A. Introducing bone marrow cells producing ADA into cells at early embryonic stages.
• B. Enzyme replacement therapy.
• C. Periodic infusion of genetically engineered lymhocytes having functional ADA cDNA.
• D. Administering adenosine deaminase activators.

Answer 1

The correct option is A Introducing bone marrow cells producing ADA into cells at early embryonic stages.

Individuals with ADA (Adenosine Deaminase) deficiency inherit defective ADA genes and are unable to produce the enzyme adenosine deaminase in their cells. The enzyme adenosine deaminase is needed to break down metabolic byproducts that become toxic to T-cell lymphocytes, and is essential to the proper functioning of the immune system. Without ADA, the toxins derived from the metabolic byproducts kill the T cells shortly after they are produced in the bone marrow. Because T cells control B cell activity, the reduction of T cells results in an absence of both T cell and B cell function called as severe combined immunodeficiency (SCID). The treatment of choice for ADA deficiency is bone marrow transplantation from a matched sibling donor at early embryonic stages . Successful bone marrow transplants can relieve ADA deficiency. The latest treatment for ADA deficiency is gene therapy. Gene therapy provides patients with their own T cells into which a normal copy of the human ADA gene has been inserted. ADA deficiency is the first disease to be treated with human gene therapy.

So, the correct answer is 'Introducing bone marrow cells producing ADA into cells at early embryonic stages.'