UPSC Prelims 2026 Q41: Genetic Medicine, Vectors & Gene Therapy

Which of the following statements with regard to genetic medicine is/are correct?

1. Genetic medicines correct/compensate for the faulty genes responsible for disease.

2. Engineered viruses and lipid nanoparticles are used as carriers of the genetic medicine.

3. Genetic medicines alter the entire DNA sequence.

  1. 1 only
  2. 2 and 3 only
  3. 1 and 2 only
  4. 1, 2 and 3

Answer: (c) 1 and 2 only

Statement-wise explanation

  • 1: correct — This is the textbook definition of gene therapy. A genetic medicine either adds a working copy of a faulty gene, edits the gene, or silences the harmful gene product. India's gene therapy trial for haemophilia A at CMC Vellore is an example: it gave patients a working Factor VIII gene, and all five participants then had an annualised bleeding rate of zero. BIRSA 101 is another: it uses an indigenous CRISPR tool (enFnCas9) to correct the defect behind sickle cell disease.
  • 2: correct — Bare DNA or RNA breaks down quickly and cannot easily enter cells, so it needs a carrier, called a vector. Engineered viruses are the classic carriers: adeno-associated virus (AAV) and lentivirus, which have been stripped of their ability to cause disease. The Vellore haemophilia trial used a lentiviral vector. Lipid nanoparticles (LNPs) are the main non-viral carrier. They delivered the mRNA COVID-19 vaccines and they carry in-body CRISPR and siRNA medicines.
  • 3: incorrect — Genetic medicines target one specific gene or one mutation, not the whole genome. A human genome has about 3 billion base pairs, and changing all of it is neither the aim nor possible. Some genetic medicines, such as mRNA, siRNA and antisense drugs, do not change DNA at all. They act on RNA or on how much protein the cell makes. The word 'entire' makes the statement false.

How to eliminate

Statement 3 is the easiest to judge. 'Alter the entire DNA sequence' is an absolute claim, and basic biology rules it out: therapies target a single gene, and rewriting a whole genome would make the cell a different organism. Once you drop statement 3, only one option is left with 1 and 2 together. You can also get there another way. Statement 1 is just the definition of the topic and is almost certainly true. That rules out the option that has 2 and 3 without 1. The remaining choice is between '1 only' and '1 and 2 only', and it depends on statement 2. To settle that, remember one fact: viral vectors (AAV, lentivirus) and lipid nanoparticles are the standard carriers. Most aspirants know about LNPs from the mRNA COVID vaccines.

Know more

Genetic medicine treats disease at the level of genes or their RNA messages, not by managing symptoms.

Main approaches

Approach What it does Example
Gene addition Adds a working copy of the gene; the faulty one stays Haemophilia A trial, CMC Vellore (lentiviral vector)
Gene editing Cuts or rewrites a specific stretch of DNA CRISPR-Cas9: Casgevy (2023), BIRSA 101 (enFnCas9)
Gene silencing Blocks a harmful gene's RNA siRNA, antisense oligonucleotides
mRNA therapy Supplies a temporary RNA instruction; DNA is not changed mRNA COVID-19 vaccines

Delivery vectors

Vector Type Key point
Adeno-associated virus (AAV) Viral Mostly stays outside the host chromosomes; used for liver and eye therapies
Lentivirus Viral Inserts into host DNA; used for blood stem cells (ex vivo)
Lipid nanoparticle (LNP) Non-viral Fat bubble that carries RNA; tends to collect in the liver

Ex vivo vs in vivo: In ex vivo therapy, a patient's cells are taken out, corrected in the lab and put back. Sickle cell CRISPR therapies work this way. In in vivo therapy, the vector is injected into the body.

Somatic vs germline: Every approved therapy is somatic. It changes body cells, and the change is not passed to children. Germline editing (of eggs, sperm or embryos) is not allowed for clinical use in India.

Indian context: The first gene therapy, in 1990, treated ADA deficiency (NCERT Class 12). India's National Sickle Cell Anaemia Elimination Mission aims to eliminate the disease by 2047. In 2026, the Drugs Rules, 1945 were amended so that the central licensing authority now covers advanced cell and gene therapies.

In the news

Gene therapy was in the Indian news repeatedly before Prelims 2026. India's first in-human gene therapy for haemophilia A, at CMC Vellore with a lentiviral vector, reported its results in December 2024. In November 2025, the Union Minister launched BIRSA 101, India's first indigenous CRISPR-based gene therapy for sickle cell disease. The question tests the basics behind these stories: what the therapy does and how it is delivered.

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