Gene therapy is a promising tool for addressing several diseases in humans. With respect to the above, which one of the following statements is FALSE?
The only successful gene therapies are those in which cells are removed from a patient, genetically modified, and then reintroduced into patients.
Gene Therapy Statement Analysis
Gene therapy is a revolutionary technique used to treat or prevent disease by changing the expression of a person's genes. It involves introducing, removing, or modifying genetic material (DNA or RNA) into cells.
Let's analyze each statement provided regarding gene therapy:
- Statement 1: Gene therapy involves the direct genetic modification of the cells/model to achieve a therapeutic goal.
This statement is TRUE. The core principle of gene therapy is the manipulation of genetic material within cells to correct a defect or add a beneficial function, thereby achieving a therapeutic effect.
- Statement 2: Current gene therapy is directed at modifying somatic cells.
This statement is generally TRUE. Most approved and current gene therapy approaches target somatic cells (non-reproductive cells) in the body. Modifying germline cells (sperm or egg cells) is technically possible but raises significant ethical and safety concerns as the changes would be heritable. Therefore, current clinical gene therapy primarily focuses on somatic cells.
- Statement 3: The only successful gene therapies are those in which cells are removed from a patient, genetically modified, and then reintroduced into patients.
This statement is FALSE. This describes an ex vivo gene therapy approach (where cells are modified outside the body and then transplanted back). While *ex vivo* therapy has been successful for certain conditions (like some immune deficiencies or blood disorders), it is not the *only* successful method. In vivo gene therapy, where the genetic material is delivered directly into the patient's body (e.g., via viral vectors injected into tissues or the bloodstream), has also shown success and is used for diseases like Leber congenital amaurosis (a form of inherited blindness) or Spinal Muscular Atrophy.
- Statement 4: Recessively inherited disorders are good targets for gene therapy.
This statement is TRUE. In recessively inherited disorders, a functional protein product is missing or deficient due to mutations in both copies of a gene. Gene therapy can often effectively treat these disorders by introducing a functional copy of the gene, allowing the cells to produce the necessary protein. This approach has shown promise for diseases like cystic fibrosis, hemophilia, and severe combined immunodeficiency (SCID).
Based on the analysis, the false statement is the one claiming that *only* *ex vivo* gene therapies have been successful, as *in vivo* methods are also used and have achieved success.
Important Questions from Transgenic animals and plants
An experiment was performed to introduce a transgenic trait in a crop plant by Agrobacterium-mediated transformation using a transgene construct in which the transgene was expressed using the CaMV 35S promoter. It was observed that expression levels of the transgenic protein were very low in all transgenic plants while transgene mRNA levels were high and variable among different plants. Further, different transgenic lines contained different numbers of the T-DNA insert. The following statements were made to explain the above observation:
A. Variations in the number of T-DNA inserts in different transgenic plants is due to more number of host cells getting infected with the T-DNA
B. Low expression levels of the transgenic protein in all transgenic plants could be due to codon usage variations between the host plant and the heterologous source of the transgene
C. The coding sequence of the transgene contained sequences that destabilized the transgene mRNA
D. Variation in copy number of T-DNA in different transgenic plants is due to variation in the promoter used to express the transgene.
Which one of the following options represents all correct
statements?Following statements were given regarding factors influencing variation in expression levels of transgene in transgenic plants:
A. Difference in restriction enzyme sites within the T-DNA.
B. Difference in copy number of the transgene.
C. Variations in site of integration of the T-DNA within the plant genome.
D. Presence of multiple promoters within the T-DNA region.
Which one of the following options represents a combination of statements that would NOT lead to variations in transgene expression levels in transgenic plants generated using the same T-DNA/binary vector?
Which one of the following statements related to genetic transformation of plants is correct?
The following statements are made regarding developing a transgenic mouse:
A. The transgenic mouse thus born will be a homozygous transgenic animal and can be maintained by crossing with another transgenic animal.
B. The fertilized transgenic eggs are allowed to develop in vitro.
C. The desired gene is preferably microinjected in male pronucleus after sperm entry in oocyte.
D. For best efficiency, the desired gene is always microinjected in the male gametes and then they are allowed to fertilize the female gametes.
E. Blastocyst stage embryos are transferred to the uterus of hormonally prepared mother.
F. The fertilized eggs are collected from specific strain of mouse.
G. The female mouse of specific strain is superovulated, oocytes are collected and allowed to fertilize in vitro.
Choose the combination of statements arranged in the correct sequence for developing transgenic mouse.
Which one of the following genomes is most appropriate to determine hybrids in plants and animals?
