Question

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

Answer 1

Hint: Gene therapy is useful for correcting a defective gene by manipulating the gene. For example, defective ADA genes can be replaced with good ones using gene therapy methods.

Complete answer: Gene therapy: It is the method of inserting DNA into an individual for the treatment of a disease. It is used to substitute a missing gene or to fix the mutant alleles.
Example: ADA is an inherited autosomal-recessive condition that occurs as a result of producing defective or deficit adenosine-deaminase (ADA) enzyme. People who have the enzyme deficiency are affected with severe combined immunodeficiency (SCID) disorder.
In the patients suffering from SCID, functional ADA genes can be introduced ex vivo as a trial of human gene therapy.
In this method, a functional gene is first inserted into a retrovirus; then it is introduced into isolated stem cells of the SCID patients.
This way ADA genes also get transferred and modified cells could be introduced again into the patient’s bone marrow.

Additional information: Gene therapy eliminates a faulty gene or adds a new gene in an attempt to cure disease or improve your body's ability to fight infections or disease.
Gene therapy holds promise for treating a wide range of diseases, like cancer, cystic fibrosis, heart disease, diabetes, hemophilia, and AIDS.

Note: In the above-mentioned process, lymphocytes are the cells that should be extracted from the patients. After re-introduction of the modified lymphocytes (as mentioned above), the gene becomes active and produces functional T-lymphocytes, and the patient’s immune system also gets activated.