Science & Technology
Biotechnology
Genome Editing, Gene Therapy, Cloning and Genomics
CRISPR-Cas9, gene therapy, stem cells, Dolly and animal cloning, DNA fingerprinting, the Human Genome Project and Genome India for CGPSC.
Prerequisites
- Genetic Engineering: Tools and Recombinant DNA Technology — restriction enzymes, vectors and PCR are used throughout this page.
- Cell and Human Body Systems — nucleus, chromosomes, blood cells.
The Hook: A Disease Named in Bastar’s Clinics
Connect
In many tribal villages of Chhattisgarh, a child with repeated joint pain, anaemia and jaundice is screened with a simple test for sickle cell disease (सिकल सेल रोग). The cause is a single-letter change in one gene for haemoglobin. For decades the only “cure” was a bone-marrow transplant from a matched donor.
In November 2023 the UK, and in December 2023 the USA, approved the world’s first medicine made with CRISPR genome editing for sickle cell disease. In November 2025 India unveiled its own indigenous CRISPR therapy, named BIRSA 101 after Bhagwan Birsa Munda. How can scientists rewrite one letter in a person’s DNA? And how is that different from gene therapy, cloning or a DNA test in a court case? This page answers those questions.
Why it matters: CRISPR, gene therapy, cloning, DNA fingerprinting and genome projects are favourite “science in news” Prelims items. Mains P-IV asks you to explain a technology and weigh its ethical issues, often with an Indian example.
Genome Editing and CRISPR-Cas9
Genome editing (जीनोम संपादन) means making a precise change at a chosen location in an organism’s DNA: deleting, correcting or inserting a few bases. Older genetic engineering mostly added a whole foreign gene at a random place; genome editing works like “find and replace” in a word processor.
| Feature | Detail |
|---|---|
| Origin | CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a natural adaptive immune system of bacteria against viruses. Bacteria store fragments of viral DNA and use them to recognise and cut the virus next time |
| Components | Cas9 — an enzyme that cuts both DNA strands (the “scissors”); guide RNA (gRNA) — a short RNA matching the target sequence (the “GPS”) |
| How it works | gRNA leads Cas9 to the matching DNA site → Cas9 makes a double-strand cut → the cell’s own repair system fixes the break, either disrupting the gene or copying in a supplied template |
| Nobel Prize | Chemistry 2020: Emmanuelle Charpentier and Jennifer Doudna, “for the development of a method for genome editing” |
| Older editing tools | Zinc-finger nucleases (ZFNs) and TALENs — accurate but harder and costlier to design |
| Newer variants | Base editing and prime editing change single letters without a double-strand break |
Site-Directed Nucleases: the categories India regulates
| Category | What is done | Foreign DNA in final plant? | India’s treatment (since 2022) |
|---|---|---|---|
| SDN-1 | Cut without a template; the cell’s repair causes a small deletion or insertion | No | Exempt from GM rules (see Agricultural Biotechnology) |
| SDN-2 | Cut with a small template that makes a specific small change | No | Exempt from GM rules |
| SDN-3 | Cut with a template carrying a whole gene | Yes | Regulated like a GMO |
CRISPR in medicine: the sickle-cell milestones
| Milestone | Detail |
|---|---|
| Casgevy (exagamglogene autotemcel) | First CRISPR-based therapy approved anywhere: UK, November 2023; USA, December 2023, for sickle cell disease and transfusion-dependent beta-thalassaemia (US approval for thalassaemia followed in January 2024). Very high cost |
| BIRSA 101 (India) | Indigenous CRISPR therapy for sickle cell disease from CSIR-IGIB (Institute of Genomics and Integrative Biology), New Delhi, unveiled in November 2025. It uses an Indian-engineered Cas9 variant (enFnCas9); the patient’s own blood stem cells are edited outside the body and infused back. Reported as aimed at a far lower cost than imported therapies; as of 2026 it is still moving through trials |
Chhattisgarh angle
Sickle cell disease is concentrated in central India’s tribal belt. A large screening of Raipur district (2007–2010) found the sickle cell trait in about 9.3% of those tested. The state runs a Sickle Cell Institute Chhattisgarh in Raipur, and the national Sickle Cell Anaemia Elimination Mission (launched 1 July 2023 at Shahdol, Madhya Pradesh) targets elimination as a public-health problem by 2047. A Mains answer on gene editing gains a strong local example here.
Gene Therapy
Gene therapy (जीन थेरेपी) treats a disease by delivering a correct gene (or editing a faulty one) into a patient’s cells.
| Point | Detail |
|---|---|
| First clinical gene therapy (NCERT example) | 1990, USA — a 4-year-old girl with ADA (adenosine deaminase) deficiency, an immune disorder. Her lymphocytes were given a functional ADA gene using a retroviral vector and returned to her body |
| Somatic vs germline | Somatic gene therapy changes body cells — not inherited. Germline therapy changes eggs, sperm or embryos — passed to children; it is ethically far more contentious and not permitted for clinical use in India |
| Ex vivo vs in vivo | Ex vivo: cells taken out, corrected, returned (ADA therapy, CAR-T, BIRSA 101). In vivo: the vector is injected straight into the body |
| Delivery vehicles | Disarmed viruses (retroviruses, lentiviruses, adeno-associated virus), lipid nanoparticles |
| Indian landmarks | NexCAR19 — India’s first indigenous CAR-T cell therapy (a gene-modified immune-cell therapy for certain blood cancers), developed by IIT Bombay and Tata Memorial Centre and commercialised by ImmunoACT; approved by CDSCO in October 2023. India’s first human gene-therapy trial for haemophilia A was run at CMC Vellore with DBT support, using a lentiviral vector |
The He Jiankui case
In 2018 Chinese scientist He Jiankui announced the birth of twin girls whose embryos he had edited with CRISPR. The work was condemned worldwide as unethical germline editing, and he was later jailed in China. It is the standard example of why germline editing is restricted.
Stem Cells
Stem cells (स्तंभ कोशिकाएँ) are unspecialised cells that can self-renew and differentiate into specialised cells.
| Type | Source | Potency |
|---|---|---|
| Embryonic stem cells | Inner cell mass of an early embryo (blastocyst) | Pluripotent — can form almost any cell type; ethically debated because the embryo is destroyed |
| Adult stem cells | Bone marrow, blood, fat tissue | Multipotent — limited to related cell types (bone-marrow cells → blood cells) |
| Umbilical cord blood | Cord blood after birth | Rich in blood-forming stem cells; stored in cord-blood banks |
| Induced pluripotent stem cells (iPSCs) | Ordinary adult cells reprogrammed | Pluripotent without using embryos; Shinya Yamanaka shared the 2012 Nobel Prize in Medicine with John Gurdon |
In India, the ICMR–DBT National Guidelines for Stem Cell Research (2017) treat the use of stem cells beyond established treatments (such as bone-marrow / blood stem-cell transplantation) as experimental — to be done only in approved clinical trials, not sold as routine therapy.
Cloning Whole Organisms
| Fact | Detail |
|---|---|
| Technique | Somatic cell nuclear transfer (SCNT): the nucleus of a body cell is put into an egg whose own nucleus has been removed; the egg is stimulated to develop and implanted in a surrogate mother |
| Dolly the sheep | First mammal cloned from an adult somatic cell; born 5 July 1996 at the Roslin Institute, Scotland (team led by Ian Wilmut); announced in 1997. The donor nucleus came from a mammary gland cell |
| India | ICAR-National Dairy Research Institute (NDRI), Karnal has produced cloned buffaloes using a simplified “hand-guided cloning” technique |
| Uses | Multiplying elite livestock, conserving endangered species, producing transgenic animals |
| Concerns | Low success rate, health problems in clones, loss of genetic diversity, and the ethical line on human reproductive cloning (widely banned) |
Transgenic animals (NCERT examples)
- Rosie (1997): the first transgenic cow, whose milk contained the human protein alpha-lactalbumin, making it more nutritionally balanced for babies.
- Transgenic sheep and mice are used to produce proteins such as alpha-1-antitrypsin (for emphysema) and to test vaccine safety and model diseases.
DNA Fingerprinting (DNA Profiling)
| Point | Detail |
|---|---|
| Inventor | Alec Jeffreys, University of Leicester, UK (1984) |
| Basis | Every person (except identical twins) has a unique pattern of repetitive DNA, especially VNTRs (variable number of tandem repeats) in satellite DNA. The number of repeats varies between people |
| Method (classical) | Isolate DNA → cut with restriction enzymes → gel electrophoresis → Southern blotting → hybridise with a labelled VNTR probe → read the band pattern. Modern profiling uses PCR of short tandem repeats (STRs) |
| Uses | Criminal forensics, disputed parentage, identifying disaster victims, wildlife forensics, population genetics |
| India | Lalji Singh of CCMB Hyderabad is called the father of DNA fingerprinting in India. The Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad is the national centre |
| Law | The DNA Technology (Use and Application) Regulation Bill, 2019 (proposing national and regional DNA data banks) was withdrawn from the Lok Sabha on 24 July 2023. As of 2026 there is no dedicated DNA-profiling statute |
Genomics: Reading Whole Genomes
| Project | Key facts |
|---|---|
| Human Genome Project (HGP) | International project, 1990–2003. Mapped the roughly 3 billion base pairs of human DNA. Humans have about 20,000 protein-coding genes (NCERT gives an older estimate of about 30,000). Less than 2% of the genome codes for proteins. A fully gap-free (“telomere-to-telomere”) sequence was published in 2022 |
| Genome India Project | Launched by the Department of Biotechnology (DBT) in 2020 to map the genetic diversity of Indians. Phase 1 sequenced about 10,000 whole genomes (10,074) from about 83 population groups. The dataset was released on 9 January 2025 and is held at the Indian Biological Data Centre (IBDC), Faridabad, through managed access |
| Uses of genomics | Precision (personalised) medicine, finding disease-causing variants (for example in sickle cell or thalassaemia), pharmacogenomics (how genes affect drug response), ancestry and population history |
| Related ideas | Proteomics (all proteins of a cell), metagenomics (DNA of whole microbial communities), bioinformatics (computers to store and analyse biological data) |
Nobel connections worth one line in an answer
- 2024 Medicine: Victor Ambros and Gary Ruvkun — discovery of microRNA and its role in gene regulation.
- 2024 Chemistry: David Baker (computational protein design) and Demis Hassabis and John Jumper (AlphaFold, protein-structure prediction).
- 2025 Medicine: Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi — peripheral immune tolerance (regulatory T cells).
Analysis for Mains: Promise and Ethical Issues
| Promise | Concerns |
|---|---|
| One-time cures for single-gene disorders (sickle cell, thalassaemia, haemophilia) | Cost and access — imported therapies cost crores of rupees; equity for tribal patients |
| Faster crop improvement without foreign DNA | Off-target edits and long-term safety are not fully known |
| Precision medicine from Indian genomic data | Genetic privacy — genomic data is the most personal data; consent and misuse (insurance, discrimination). Privacy is a Fundamental Right after Puttaswamy (2017) — see Fundamental Rights |
| Forensic justice through DNA profiling | Germline editing and “designer babies” — consent of future generations, eugenics |
| Biotech jobs and start-ups | Regulatory gaps (no DNA-profiling law; evolving rules for gene therapy) |
Memory Tricks
CRISPR = 'GPS + Scissors'
Guide RNA is the GPS, Cas9 is the scissors. “Charpentier and Doudna Cut DNA” — Chemistry Nobel 2020 (the COVID year: “20-20 vision for DNA”).
Dolly: '96, Roslin, Mammary'
Dolly was born in ‘96 at Roslin from a mammary cell — “Dolly Rolled out of a Mammary cell in ‘96”.
Don’t Confuse
| This | vs | That |
|---|---|---|
| Gene therapy — add or fix a gene in a patient to treat disease | vs | Genome editing — the tool for precise changes; used in therapy, crops and research |
| Somatic editing — not inherited | vs | Germline editing — inherited; restricted |
| SDN-1/SDN-2 — no foreign DNA; exempt in India | vs | SDN-3 — foreign gene inserted; treated as GM |
| Gene cloning — copies of a gene | vs | Reproductive cloning — copy of an organism (Dolly) |
| Embryonic stem cells — pluripotent, embryo destroyed | vs | iPSCs — pluripotent, made from adult cells |
| CDFD Hyderabad — DNA fingerprinting and diagnostics | vs | CCMB Hyderabad — Centre for Cellular and Molecular Biology (Lalji Singh’s original institute) |
| Casgevy — first CRISPR therapy (UK/US, 2023) | vs | BIRSA 101 — India’s indigenous CRISPR therapy (unveiled 2025) |
Common Mistakes
MCQ traps
- “CRISPR was invented by scientists as an artificial system.” False. It is adapted from a natural bacterial immune system.
- “Dolly was cloned from an embryonic cell.” False. She was the first mammal cloned from an adult somatic (mammary gland) cell.
- “Genome-edited plants are always GMOs under Indian rules.” False. Since 2022, SDN-1 and SDN-2 plants without foreign DNA are exempt from the GM rules.
- “Somatic gene therapy changes are passed to children.” False. Only germline changes are inherited.
- “DNA fingerprinting reads the whole genome.” False. It compares a small set of repetitive regions (VNTRs/STRs).
Practice
All questions below are original practice questions written in CGPSC style. They are not previous-year questions.
Level 1: Foundation
- In CRISPR-Cas9, the molecule that takes Cas9 to the correct DNA site is the ______.
- Dolly the sheep was cloned at the ______ Institute in Scotland.
- DNA fingerprinting is based on variable number of ______ repeats.
Answers
- Guide RNA (gRNA).
- Roslin Institute.
- Tandem repeats (VNTRs).
Level 2: Prelims MCQs
Q1. Consider the following statements:
- CRISPR-Cas9 is derived from a natural defence system found in bacteria.
- The Nobel Prize in Physiology or Medicine 2020 was awarded for developing CRISPR-Cas9.
- In India, genome-edited plants of the SDN-1 and SDN-2 categories that carry no foreign DNA are exempt from the rules governing genetically engineered organisms.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 1 and 3 only
- (c) 2 and 3 only
- (d) 1, 2 and 3
Answer and explanation
(b) 1 and 3 only. CRISPR is adapted from bacterial adaptive immunity. The 2020 award to Charpentier and Doudna was the Chemistry prize, not Medicine. The MoEFCC office memorandum of 30 March 2022 exempted SDN-1 and SDN-2 plants without foreign DNA from Rules 7–11 of the Rules of 1989.
Q2. Match List I (Item) with List II (Associated fact):
| List I | List II |
|---|---|
| A. Dolly | 1. Alec Jeffreys |
| B. DNA fingerprinting | 2. Somatic cell nuclear transfer |
| C. iPSCs | 3. Indian Biological Data Centre |
| D. Genome India data | 4. Shinya Yamanaka |
- (a) A-2, B-1, C-4, D-3
- (b) A-2, B-4, C-1, D-3
- (c) A-1, B-2, C-4, D-3
- (d) A-2, B-1, C-3, D-4
Answer and explanation
(a) A-2, B-1, C-4, D-3. Dolly came from SCNT; Alec Jeffreys developed DNA fingerprinting (1984); Yamanaka created induced pluripotent stem cells (Nobel 2012); Genome India data is stored at IBDC, Faridabad.
Q3. BIRSA 101, unveiled in India in 2025, is:
- (a) A genetically modified rice variety tolerant to salinity
- (b) An indigenous CRISPR-based gene therapy for sickle cell disease
- (c) A recombinant vaccine against tuberculosis
- (d) A satellite for monitoring tribal forest lands
Answer and explanation
(b). BIRSA 101 is an indigenous CRISPR gene therapy for sickle cell disease from CSIR-IGIB, named after Bhagwan Birsa Munda because the disease particularly affects tribal communities.
Q4. Which of the following best describes somatic gene therapy?
- (a) Changing genes in sperm or eggs so the change is inherited
- (b) Changing genes in body cells to treat the patient, without passing the change to offspring
- (c) Cloning a patient’s body cells to make a new organism
- (d) Replacing a patient’s entire genome with a donor genome
Answer and explanation
(b). Somatic therapy affects only the treated person. Germline therapy (a) alters inherited cells and is restricted for ethical reasons.
Q5. The Human Genome Project:
- (a) Was completed in 1997, the year Dolly was announced
- (b) Showed that more than half of human DNA codes for proteins
- (c) Ran from 1990 to 2003 and sequenced about 3 billion base pairs
- (d) Was an Indian project led by the Department of Biotechnology
Answer and explanation
(c). The HGP was an international project (1990–2003). Less than 2% of the genome codes for proteins. India’s own population-scale effort is the separate Genome India Project (2020).
Level 3: Mains Answer Writing
Q1. (60 words) What is gene therapy? Distinguish between somatic and germline gene therapy.
Model answer outline
- Definition: treating disease by inserting a correct gene or editing a faulty one in a patient’s cells; first used in 1990 for ADA deficiency.
- Somatic: body cells; affects only the patient; accepted under regulation (CAR-T NexCAR19, BIRSA 101).
- Germline: eggs, sperm or embryos; inherited; banned for clinical use in most countries, including India.
Q2. (150–200 words) “Genome editing can transform health care for Chhattisgarh’s tribal population, but it raises serious ethical questions.” Discuss.
Model answer outline
- Intro: CRISPR-Cas9 (Nobel Chemistry 2020) allows precise DNA changes; the first CRISPR therapy (Casgevy) was approved in 2023 for sickle cell disease.
- Promise:
- Sickle cell disease is widespread in central India’s tribal belt; Raipur district screening found the trait in about 9% of people.
- India’s indigenous BIRSA 101 (CSIR-IGIB, 2025) aims at a far cheaper one-time cure than imported options.
- Genome India data (10,074 genomes, released 2025) helps identify Indian disease variants.
- Ethical issues: cost and equitable access; informed consent in low-literacy settings; off-target effects; genomic privacy (Puttaswamy, 2017); slippery slope to germline editing (He Jiankui, 2018).
- Way forward: public funding, trials with community consent, strong data-protection safeguards, screening and counselling under the Sickle Cell Anaemia Elimination Mission.
- Conclusion: gene editing should complement — not replace — screening, prevention and primary health care in tribal districts.
Quick Revision Table
| Fact | Detail |
|---|---|
| CRISPR origin | Bacterial adaptive immunity against viruses |
| CRISPR parts | Cas9 (cuts) + guide RNA (targets) |
| Nobel Chemistry 2020 | Emmanuelle Charpentier, Jennifer Doudna |
| SDN-1 / SDN-2 | No foreign DNA; exempt from GM rules (MoEFCC, 30 March 2022) |
| Casgevy | First CRISPR therapy; UK Nov 2023, USA Dec 2023 |
| BIRSA 101 | India’s indigenous CRISPR therapy for sickle cell (CSIR-IGIB, Nov 2025) |
| First gene therapy | 1990, ADA deficiency |
| NexCAR19 | India’s first CAR-T therapy; CDSCO approval Oct 2023 |
| iPSCs | Shinya Yamanaka; Nobel 2012 |
| Dolly | Born 5 July 1996; Roslin Institute; SCNT; mammary cell |
| DNA fingerprinting | Alec Jeffreys, 1984; VNTRs; Lalji Singh; CDFD Hyderabad |
| DNA Bill 2019 | Withdrawn 24 July 2023 |
| Human Genome Project | 1990–2003; about 3 billion bp; about 20,000 genes |
| Genome India | DBT, 2020; 10,074 genomes; data released 9 Jan 2025; IBDC Faridabad |
Key Takeaways
Key Takeaways
- CRISPR-Cas9 is a guided pair of scissors borrowed from bacteria; it made genome editing cheap and precise.
- India regulates genome-edited plants by category: SDN-1 and SDN-2 (no foreign DNA) are exempt; SDN-3 is treated as GM.
- Gene therapy is somatic (allowed under regulation) or germline (restricted); India has NexCAR19 and BIRSA 101 as landmarks.
- Dolly (1996) proved an adult cell can be reprogrammed into a whole organism; DNA fingerprinting relies on repetitive DNA.
- Genome India (data released 2025) gives Indian precision medicine its own reference — and raises genetic-privacy questions.
What’s Next
- Agricultural Biotechnology — how genome editing produced India’s first edited rice varieties
- Medical Biotechnology — vaccines, monoclonal antibodies and diagnostics
- Regulation, Policy and Ethics — who approves what, and the ethical debate
- Tribes of Chhattisgarh — the communities most affected by sickle cell disease
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