Genetic Medicine: How Gene Therapy Works

In November 2025, doctors in India took blood stem cells from a sickle-cell patient, edited one faulty gene, and put the cells back. No donor, no lifelong medicine — just a corrected gene. That therapy, BIRSA-101, is genetic medicine: treatment that fixes the DNA behind a disease, not just its symptoms.

CRISPR-Cas9: the Cas9 protein and a guide RNA locate and edit a specific gene. Credit: Ernesto del Aguila III, NHGRI, CC BY 2.0, via Wikimedia Commons.

MCQ Questions

SCITECH0134

2 Carrier Types

Viral vectors and lipid nanoparticles deliver genetic medicine

Genetic medicine: correcting faulty genes, not rewriting the genome.

Viral Vectors

AAV, Lentivirus

Engineered, disease-causing genes removed.

Non-Viral

Lipid Nanoparticles

Used in COVID mRNA vaccines too.

First CRISPR Drug

Casgevy, 2023

FDA-approved, for sickle cell disease.

India’s First

BIRSA-101, 2025

Indigenous CRISPR therapy, CSIR-IGIB.

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📑 Contents

1What Is Genetic Medicine?
2How It’s Delivered: Viral and Non-Viral Carriers
3Test Yourself
4Types and Approaches
5Current Affairs

🧬 What Is Genetic Medicine?

1. Fixing the Gene, Not the Whole Genome

Core Idea Genetic medicine corrects or compensates for the specific faulty gene causing a disease. It does not rewrite a patient’s entire DNA sequence — a common exam trap.
How Treatments either replace a broken gene, silence a harmful one, or edit a precise DNA sequence, depending on the disease and the tool used.
Milestone Luxturna, approved by the US FDA in 2017, was the first gene therapy using a viral vector (AAV) approved in the United States. It treats an inherited retinal disease.
Milestone Casgevy, approved in the UK and US in 2023, became the first CRISPR gene-editing therapy ever approved. It treats sickle cell disease.

💉 How It’s Delivered: Viral and Non-Viral Carriers

1. Engineered Viruses

Viral Vectors Scientists disable a virus’s disease-causing ability, then use its natural skill at entering cells to carry a therapeutic gene inside.
AAV Adeno-associated virus (AAV) vectors give durable gene expression in non-dividing tissue, such as the eye. Luxturna uses AAV.
Lentivirus Lentiviral vectors integrate their cargo into the host genome. This suits therapies engineered outside the body, on cells that will keep dividing.

2. Lipid Nanoparticles

Non-Viral Lipid nanoparticles (LNPs) are tiny, fat-based spheres. They encapsulate fragile genetic material like mRNA or DNA and protect it until it reaches the target cell.
Proven at Scale The same LNP technology behind COVID-19 mRNA vaccines is now used to deliver other genetic medicines, including some CRISPR-based ones.
Why It Matters LNPs are easier to manufacture than viral vectors and trigger a smaller immune response, though they don’t always integrate as permanently.

Test Yourself

🔬 Types and Approaches

1. Somatic vs Germline

Somatic Somatic gene therapy edits a patient’s own body cells. The change is not passed on to their children. Nearly all approved therapies today are somatic.
Germline Germline therapy would edit cells that pass genes to future generations. It remains banned or tightly restricted worldwide, for ethical and safety reasons.

2. Ex Vivo vs In Vivo

Ex Vivo Cells are removed from the patient, edited in a lab, then infused back in. BIRSA-101 uses this approach on blood stem cells.
In Vivo The carrier is given directly to the patient, and editing happens inside the body. Casgevy and most LNP-based therapies work this way.
CAR-T CAR-T cell therapy engineers a patient’s immune cells to hunt cancer. It began as an ex vivo technique, and in vivo CAR-T versions are now in development.

For India’s broader Science and Technology achievements, including its genomics push, see SciTech0127 — Genome India Project. For the specific gene-editing tool behind several of these therapies, see SciTech0123 — CRISPR: Gene-Editing Technology.

Previous Year Question

Asked as: “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.” (UPSC CSP 2026, GS Paper I). Answer: 1 and 2 only — statement 3 is wrong, since genetic medicine targets specific faulty genes rather than rewriting the entire DNA sequence.

🧬 Current Affairs (2025-26)

1. Recent Developments

India’s First 19-20 Nov 2025: BIRSA-101 Launched: Union Minister Dr Jitendra Singh launched India’s first indigenous CRISPR-based gene therapy, developed by CSIR-IGIB with the Serum Institute of India, for sickle cell disease. (Source: PIB)
How It Works 2025: BIRSA-101 uses CRISPR-Cas9 to edit the faulty HBB gene in a patient’s own blood stem cells, restoring normal haemoglobin production. It is named after tribal freedom fighter Birsa Munda.
Cost 2025: Globally, CRISPR-based gene-editing therapy for sickle cell disease costs roughly ₹20-25 crore per patient. India’s indigenous platform is expected to cost around ₹50 lakh.
Trials 2026: Clinical trials, run jointly by CSIR-IGIB, the Serum Institute, and AIIMS Delhi, are set to begin with participants from Madhya Pradesh, Chhattisgarh, and Jharkhand — states with a high tribal population burden of sickle cell disease.