Q. Consider the following statements:

  1. Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent.
  2. A person’s genome can be edited before birth at the early embryonic stage.
  3. Human induced pluripotent stem cells can be injected into the embryo of a pig.

Which of the statements given above is/are correct?

  • 1 only
  • 2 and 3 only
  • 2 only
  • 1, 2 and 3

Answer: (d) 1, 2 and 3

Gene Therapy
  • Gene therapy refers to the method wherein a genetic defect is treated by inserting a functional gene or section of DNA in cells. The functional gene inserted into an individual or an embryo compensates for the non-functional gene present. The newly inserted DNA corrects the effect of the mutated gene.
  • On the basis of types of cells involved in the gene transfer, gene therapy is of two types:
    • Somatic gene therapy: Here the desired gene is transferred to a somatic cell. The gene is not transferred to the offspring.
    • Germline gene therapy: Here the desired gene is introduced in the germ cell. The gene gets transferred from one generation to another generation.
Germline gene therapy
  • Under this therapy, required DNA is transferred into the cells that produce reproductive cells, eggs or sperm, in the body. 
  • It allows for the correction of disease-causing gene variants that are certain to be passed down from generation to generation. This therapy removes a hereditary disorder from a family line forever.
Somatic cell gene therapy
  • Somatic cell gene therapy is when therapeutic genes are transferred to a patient’s somatic cells.
  • The somatic gene therapy targets body tissues. These cells do not produce sperm or eggs, therefore the gene is not transferred to the next generation.
  • Somatic cell gene therapy would aim to cure a disease only in the patient, not in the patient’s descendants.
​Human-induced pluripotent stem cells
  • They have been hailed as an effective replacement for human embryonic stem cells and a prime candidate cell source for regenerative medicine aims.
  • The researchers tried combining human induced pluripotent stem cells with pig embryos.
  • Many of the embryos were much smaller than normal and seemed to grow more slowly. 
  • Hence, so far there has not been a success in growing human organs in pigs.
  • But this experiment shows that human-induced pluripotent cells can be injected into pigs embryo.