Genetic Medicine: How Gene Therapy Works

1.1 What is genetic medicine?

Gene therapy is a medical approach that treats or prevents disease by correcting the underlying genetic problem. MedlinePlus, a US National Library of Medicine (NLM) service, defines it this way. The UPSC question uses the words genetic medicine. Treating the two terms as one idea is our own reading.

The NLM site says the instructions for making proteins are carried in a person’s genetic code. A variant, or mutation, in this code can change how a protein is made or how it works. Fixing or compensating for the change may let the protein do its job again.

1.2 What are the main ways to fix a gene?

Bulcha and colleagues, in a 2021 review, list four basic approaches.

• Gene replacement: delivering a functional gene to replace a non-working gene.
• Gene silencing: inactivating a mutated gene that has become toxic to cells.
• Gene addition: over-expressing a “foreign” gene to affect how cells work.
• Gene editing: a permanent manipulation of a gene in a patient’s genome.

The NLM site calls genome editing a newer technique. CRISPR-Cas9 is a well-known type. The NLM site says genome editing is being studied for four jobs.

• Fix a genetic alteration, so the gene can function properly.
• Turn on a gene to help fight a disease.
• Turn off a gene that is functioning improperly.
• Remove a piece of DNA that is impairing gene function and causing disease.

1.3 Does genetic medicine rewrite the whole genome?

No. This is the trap in the UPSC statement. The NLM site says genome editing allows genetic material to be added, removed or altered. This happens at precise locations in the genome. The target is a specific place. It is not the entire DNA sequence.

Here is our own analogy. A faulty gene is like a typing error on one page of a long book. Genetic medicine corrects that page. It does not reprint the whole book.

2.1 Why does a gene need a carrier?

The NLM site says genetic material or gene-editing tools usually do not work if placed straight into a cell. So a carrier called a vector is built to carry and deliver the material.

2.2 Why use a virus as the carrier?

Certain viruses are used as vectors. They can deliver material by infecting the cell. The NLM site says these viruses are modified. They can’t cause disease when used in people. That matches the words engineered viruses in the UPSC statement.

In their 2021 review, Bulcha and colleagues call adenoviruses, adeno-associated viruses (AAV) and lentiviruses the three key vector strategies.

The table covers only three vectors. Bulcha and colleagues name them as key. It leaves out other viral vectors and the non-viral carriers in card 3. Episomal means a form that stays apart from the chromosomes; that plain gloss is our own.

2.3 What are the risks of viral carriers?

The NLM site says gene therapy with viral vectors has been successful. It does carry some risk.

• Sometimes the virus triggers a dangerous immune response.
• Vectors that integrate genetic material into a chromosome can cause errors that lead to cancer.

The NLM site adds that some viruses, such as retroviruses, integrate their genetic material into a chromosome. Others, such as adenoviruses, do not.

3.1 What is a nanoparticle carrier?

The NLM site says researchers are developing newer technologies. They deliver genetic material or gene-editing tools without using viruses. One technique uses special structures called nanoparticles as vectors. The NLM site describes nanoparticles as incredibly small structures.

Duan and colleagues list lipid nanoparticles (LNPs) among the nano-delivery systems for CRISPR/Cas9. A lipid is a fatty molecule. That plain gloss is our own.

3.2 Why do researchers like them?

The NLM site says nanoparticles are less likely than viral vectors to cause immune reactions. It also says they are easier to design and modify for specific purposes.

Those are the NLM site’s comparisons. It also says gene therapy with viral vectors has been successful.

3.3 Are COVID-19 mRNA vaccines the same as genetic medicine?

Verbeke and colleagues write that the COVID-19 mRNA vaccines are made of synthetic mRNA strands. Lipid nanoparticles pack them and deliver them to cells. So LNPs are a carrier used in those vaccines.

But the NLM site says mRNA from vaccines does not enter the nucleus and does not alter DNA. Sharing a carrier is not the same as editing DNA. That link between the two sources is our own reading.

4.1 What does ex vivo mean?

Ex vivo therapy works outside the body. Bulcha and colleagues describe the steps. A patient’s cells are taken out. A vector carrying a therapeutic gene changes them. They are grown in culture. Then they are infused back into the patient.

The NLM site describes the same idea. A sample of the patient’s cells is removed. In a laboratory, it is exposed to the vector. The cells containing the vector are then returned to the patient.

4.2 What does in vivo mean?

In vivo therapy works inside the body. Bulcha and colleagues say it means giving the vector, which carries a healing gene, straight to the patient.

The NLM site says the vector can be injected, or given by IV, straight into one tissue. There it is taken up by individual cells.

The ex vivo and in vivo labels for named products in this lesson are our own reading of these definitions.

4.3 Where does cancer CAR-T therapy fit?

Bulcha and colleagues describe a trial. A patient’s own T cells were transduced with lentiviral vectors. The vectors carried a transgene. It makes a chimeric antigen receptor (CAR) that binds CD19. They say this treatment, sold as Kymriah, later became the first FDA-approved drug for a childhood leukaemia.

The table covers only the two routes in the sources above. The last row is our own reading of the definitions. The sources do not use those labels for these products.

5.1 Which cells do doctors change?

The NLM site says current gene therapy research has focused on body (somatic) cells. Examples are bone marrow or blood cells. It says this type of change cannot be passed to a person’s children.

This is the NLM site’s wording as of its page update on 28 February 2022.

5.2 What is germline therapy?

Gene therapy could be aimed at egg and sperm cells. The NLM site calls these germ cells. This would let the changes pass to future generations. It calls this germline gene therapy and says the idea is controversial.

The National Human Genome Research Institute says germline editing changes would pass to future generations.

5.3 Why is it controversial?

The NLM site lists these concerns.

• Germline changes might affect the development of a fetus in unexpected ways.
• Long-term side effects are not yet known.
• People who would be affected are not yet born, so they cannot choose the treatment.

The NLM site also says the US Government does not allow federal funds for germline gene therapy research in people. The National Human Genome Research Institute says about 40 countries discouraged or banned germline editing research as of 2014. Neither source says germline therapy is banned everywhere today.

6.1 What is Luxturna?

The prescribing information calls Luxturna an adeno-associated virus vector-based gene therapy. It is indicated for patients with a confirmed biallelic RPE65 mutation. The mutation causes retinal dystrophy. The label says it is for subretinal injection only. The label gives its initial US approval as 2017.

Bulcha and colleagues call Luxturna the second AAV drug to gain commercial approval. They say Glybera was the first AAV-based gene therapy approved for sale. The European Medicines Agency approved it in 2012.

They also say Luxturna delivers RPE65, the gene affected in Leber’s congenital amaurosis. It launched at $425,000 per eye.

6.2 What is Casgevy?

The UK regulator, the MHRA, authorised Casgevy on 16 November 2023. It said Casgevy was the first medicine licensed that uses CRISPR. The MHRA licence covers sickle-cell disease and transfusion-dependent beta-thalassaemia. It is for patients aged 12 and over.

The US FDA approved it on 8 December 2023. The FDA calls Casgevy the first FDA-approved therapy using CRISPR/Cas9. This is a type of genome editing technology. It says Casgevy and Lyfgenia are the first cell-based gene therapies for sickle cell disease.

The MHRA says stem cells are taken out of bone marrow and edited in a laboratory. They are then put back into the patient.

The FDA says both products are made from the patient’s own blood stem cells. They are given back as a one-time, single-dose infusion.

For Lyfgenia, the FDA says the blood stem cells are genetically modified to produce HbAT87Q.

6.3 What is sickle cell disease?

The MHRA says sickle-cell disease and beta-thalassaemia are genetic conditions. They are caused by errors in the genes for haemoglobin. Red blood cells use haemoglobin to carry oxygen around the body.

The MHRA says sickle-cell disease can lead to attacks of very severe pain. It can also cause serious infections and anaemia.

The table covers only these two products. It leaves out Lyfgenia and other approved therapies.

7.1 What happened on 14 May 2026?

The Ministry of Tribal Affairs, CSIR and CSIR-IGIB held a workshop on BIRSA 101 at CSIR-IGIB, New Delhi, on 14 May 2026. PIB says the Ministry of Tribal Affairs has supported the project with financial assistance of approximately Rs. 3.75 crores.

PIB says participants were briefed on the phased progress of trial facilities. They also heard about rules and partnerships. It says the workshop highlighted the transfer of the technology framework to Serum Institute of India Pvt. Ltd. for collaborative clinical and manufacturing development. The release does not report trial results.

7.2 What was announced on 19 November 2025?

PIB reported that Union Minister Dr Jitendra Singh launched India’s first home-made CRISPR gene therapy for sickle cell disease. The therapy is named BIRSA 101. It says it is dedicated to Bhagwan Birsa Munda, remembered as a great tribal freedom fighter.

PIB says the work was developed at CSIR-Institute of Genomics and Integrative Biology (IGIB). CSIR-IGIB and the Serum Institute of India exchanged a technology transfer and collaboration agreement. It covers IGIB’s engineered enFnCas9 CRISPR platform.

The Minister described the approach as a “precise genetic surgery”. He tied it to the Prime Minister’s vision of a Sickle Cell-Free India by 2047.

7.3 What did the releases say about cost?

PIB says the Minister spoke of the potential to replace treatments priced at Rs. 20-25 crore overseas. Dr Umesh Shaligram of the Serum Institute is quoted as saying that gene therapies cost over three million dollars worldwide.

Neither release gives a price for BIRSA 101 itself. PIB’s account of the 14 May 2026 workshop gives no trial results. Treat both as launch-stage news as of those dates.

Why it matters for the exam: BIRSA 101 is described by PIB as India’s first indigenous CRISPR-based therapy. It shows how genome editing links to public health and tribal welfare. This is our own note on why the item may be asked.

8.1 What exactly did UPSC ask?

This appeared in the Civil Services (Preliminary) Examination 2026. It was Question 41 in the Series A booklet of General Studies Paper I. The official words are below.

UPSC’s provisional answer key for Series A gives option (c), 1 and 2 only, for Question 41. The key is marked provisional. No final key had been published.

See UPSC CSP 2026 GS Paper I, full question paper.

8.2 Which statements were right and why?

Statement wording is shortened here. The full official wording is above.

8.3 How can you eliminate options step by step?

• Statement 3 is wrong, so any option that includes statement 3 is out.
• That removes the options “2 and 3 only” and “1, 2 and 3”.
• Statement 2 is correct, so “1 only” is incomplete.
• The option “1 and 2 only” is left, and it matches the provisional key.

8.4 Quick Q&A