Question 96 from UPSC CSE 2019 - Science & Technology

Question

âRNA interference (RNAi)â technology has gained popularity in the last few years. Why?
1. It is used in developing gene silencing therapies.
2. It can be used in developing therapies for the treatment of cancer.
3. It can be used to develop hormone replacement therapies.
4. It can be used to produce crop plants that are resistant to viral pathogens.
Select the correct answer using the code given below.

Accepted Answer

Correct Option: A. 1, 2, and 4

Strategy: Focus on the core function of RNA interference — gene silencing. This aligns statements 1 and 4 directly with established applications: silencing genes (therapies, statement 1) and making virus-resistant crops (statement 4). Statement 2 is about cancer therapy, which is also a significant area of RNAi research and application. Statement 3, hormone replacement, is not associated with RNAi, making it an outlier. Thus, select the options that match the main uses and eliminate the irrelevant one.

Key Info: RNA interference (RNAi) is a natural biological process where RNA molecules inhibit gene expression by neutralizing targeted messenger RNA (mRNA) molecules. This mechanism effectively 'silences' specific genes.

- RNAi Technology:
  - Discovered in 1998, it is widely used in research for gene function analysis and therapeutics.
  - Utilizes small RNA molecules such as small interfering RNA (siRNA) or microRNA (miRNA) to specifically target and degrade complementary mRNA, blocking the synthesis of specific proteins.

- Medical Applications:
  - Gene Silencing Therapies (Statement 1): RNAi is at the forefront of developing therapies to silence mutant or harmful genes, including those responsible for genetic disorders.
  - Cancer Treatment (Statement 2): Experimental and clinical trials employ RNAi to target and silence genes that drive cancer cell proliferation, metastasis, or resistance to therapy. Some RNAi-based drugs have reached clinical trial stages for cancers.
  - Hormone Replacement Therapy (Statement 3): Not connected to RNAi, as this therapy is based on supplying deficient hormones rather than altering gene expression pathways.

- Agricultural Applications:
  - Virus-resistant Crops (Statement 4): RNAi is used to engineer crops (such as papaya, cotton, and tomato) with resistance to viral pathogens. By introducing specific RNAi constructs, the plants can silence viral genes, conferring protection against diseases.

- Regulatory and Social Context:
  - Unlike some transgenic methods (e.g., Bt crops using foreign proteins), RNAi-based modifications often involve targeting endogenous plant genes or viral sequences, sometimes facing less regulatory resistance.

- Examples:
  - The development of the first RNAi-based therapeutic (Patisiran) approved for treating hereditary transthyretin-mediated amyloidosis.
  - Papaya ringspot virus-resistant papaya developed using RNAi technology.

Answer

Option B: 2 and 3

Answer

Option C: 1 and 3

Answer

Option D: 1 and 4 only