Question
Which of the following statements with regard to genetic medicine is/are correct?
1Genetic medicines correct/compensate for the faulty genes responsible for disease.
2Engineered viruses and lipid nanoparticles are used as carriers of the genetic medicine.
3Genetic medicines alter the entire DNA sequence.
A1 only
B2 and 3 only
C1 and 2 only
D1, 2 and 3
🧬 Simple Analogy to Understand This Question
Think of your DNA as a book with 3 billion letters. A genetic disease is caused by one or a few wrong letters (faulty genes). Genetic medicine is like a highly precise “find and replace” function — it finds the specific wrong letter and corrects just that. It does NOT rewrite the entire book. Statement 3 says “alter the entire DNA sequence” — which would be rewriting all 3 billion letters. That is neither the goal nor scientifically possible.
Each Statement — Verified Against Scientific Facts
1
“Genetic medicines correct/compensate for the faulty genes responsible for disease” — TRUE
This is the fundamental principle of genetic medicine (gene therapy). It works through several mechanisms:
Correct/compensate for faulty genes
✓ Correct
• Gene replacement — delivering a functional copy of the faulty gene (e.g., for cystic fibrosis, hemophilia)
• Gene correction — directly editing the faulty sequence (CRISPR-Cas9)
• Gene silencing — switching off a harmful gene (RNA interference / siRNA)
• Gene compensation — providing compensating proteins via mRNA (e.g., mRNA vaccines, exon-skipping for Duchenne Muscular Dystrophy)
✓ Core principle of gene therapy
Fix, replace, silence, or compensate for specific faulty genes — not random or wholesale changes
2
“Engineered viruses and lipid nanoparticles are used as carriers of the genetic medicine” — TRUE
Genetic material (DNA, mRNA, siRNA) cannot enter cells on its own — it needs delivery vehicles called vectors.
Engineered viruses and lipid nanoparticles as carriers
✓ Correct
Viral vectors (engineered viruses):
🦠 Viral Vectors
AAV (Adeno-Associated Virus) · Lentivirus · Adenovirus · Retroviruses · Natural cell-infecting ability repurposed for therapeutic delivery
🔬 Lipid Nanoparticles (LNPs)
Non-viral delivery · Used in COVID-19 mRNA vaccines (Pfizer/Moderna) · Encapsulate mRNA/DNA · Fuse with cell membrane to deliver cargo
✓ Both are standard delivery vehicles
Viral vectors (AAV, lentivirus) = biological carriers · LNPs = non-viral carriers · Both deliver therapeutic genes into target cells
3
“Genetic medicines alter the entire DNA sequence” — FALSE
This statement is scientifically incorrect on two levels:
“Alter the entire DNA sequence”
✗ Factually Wrong
1. Not the objective: Genetic medicines target specific faulty genes or gene segments. Advanced techniques like CRISPR-Cas9, base editing, and prime editing are praised precisely for their specificity — they target a single nucleotide or short sequence without affecting the rest of the genome.
2. Not scientifically possible: The human genome has approximately 3 billion base pairs across 23 chromosome pairs. Altering the entire DNA sequence of every cell in a body is computationally, biologically, and physically impossible. Even if attempted, it would be immediately lethal — cells cannot function with their entire genetic code being rewritten simultaneously.
The goal is the opposite of Statement 3: Precision. The entire field of genetic medicine moved from whole-gene replacement toward increasingly precise editing — from gene therapy → gene editing → base editing → prime editing → epigenome editing. Each generation is MORE targeted, not less.
✗ Wrong — precise targeting, not wholesale alteration
3 billion base pairs in human genome. CRISPR targets 1 specific gene/sequence. Statement 3 describes the opposite of what genetic medicine does.
Genetic Medicine — Key Facts for UPSC
| Parameter | Detail |
| What it is | Genetic medicine / gene therapy = treating disease by modifying a patient’s genes · Targets root cause (faulty gene), not just symptoms |
| Mechanisms | Gene replacement · Gene correction (CRISPR) · Gene silencing (siRNA/RNAi) · Gene compensation (mRNA therapy) · Exon skipping |
| Viral carriers | AAV (Adeno-Associated Virus) — most common · Lentivirus · Adenovirus · Retrovirus · Natural pathogen-derived; engineered to remove harmful genes |
| Non-viral carriers | Lipid Nanoparticles (LNPs) — used in COVID mRNA vaccines · Polymer nanoparticles · Liposomes · Protein-based carriers |
| CRISPR-Cas9 | Precise gene editing · Targets specific DNA sequence using guide RNA · Does NOT alter entire genome · Nobel Prize 2020 (Doudna and Charpentier) |
| Statement 3 error | 3 billion base pairs in human genome. Genetic medicines target specific genes ONLY. Altering entire DNA = medically unnecessary + scientifically impossible. |
| Approved therapies | Luxturna (eye disease) · Zolgensma (SMA) · Hemgenix (hemophilia) · mRNA COVID-19 vaccines · CAR-T cell therapies |
| India relevance | GenomeIndia Project (DBT) · India’s gene therapy regulatory framework being developed · CDSCO guidelines on gene therapy under revision |
Memory Trick
🧠 Remember It This Way
Statement 3 is instantly wrong — “entire DNA sequence”: The word “entire” is the flag. Genetic medicine is about precision — targeting ONE faulty gene among ~20,000 genes. “Entire DNA sequence” = all 3 billion base pairs. Impossible and unnecessary.
LNPs = COVID vaccine technology: The Pfizer and Moderna mRNA COVID-19 vaccines used lipid nanoparticles to deliver mRNA into cells. This is the same technology used in genetic medicine. If you remember COVID vaccines = LNPs, you can confirm Statement 2.
Gene therapy = fix the typo, not rewrite the book: Your DNA is a 3-billion-letter book. A genetic disease is one wrong letter. CRISPR finds that one letter and corrects it. Statement 1 = correct the faulty gene. Statement 2 = the delivery envelope. Statement 3 = rewriting the whole book = WRONG.
