What is gene therapy and give a basic example of its concept?

• A. Removing a gene to prevent disease.
• B. Using vaccines to train the immune system.
• C. Changing an organism's phenotype by environmental factors.
• D. Introducing a healthy gene to treat a disease; e.g., delivering functional genes to correct a genetic deficiency.

Answer: (D)

Gene therapy is about delivering a healthy gene into a person’s cells to fix a disease caused by a faulty gene. By providing a functional copy, the hope is that the cells can produce the missing or defective protein and restore normal function. This delivery can be done directly into the body or by modifying cells outside the body and then placing them back. Examples include supplying a functioning gene to treat certain inherited disorders, such as ADA-SCID, or delivering genes to retinal cells in hereditary blindness. The key idea is adding or correcting a gene to address the genetic defect, rather than removing a gene, using vaccines, or changing traits through the environment.