C
CraftExam
high importancemedium8 min

Gene Therapy

Gene therapy is a biotechnological approach in which a functional gene is introduced into a person's cells to compensate for a defective or missing gene responsible for a disorder.

Concept Practice Coming Soon

Learn the concept

Student-friendly explanation

Gene therapy aims to correct a disorder at the genetic expression level by supplying a functional copy of a gene. The Class 12 focus is ADA deficiency, a disorder affecting immune function due to lack of adenosine deaminase enzyme. In ex-vivo gene therapy, cells are removed from the patient, genetically modified outside the body, and returned. In in-vivo gene therapy, the therapeutic gene is delivered directly into the body. The first clinical gene therapy example commonly tested is ADA deficiency. Students should also mention limitations: treatment may need repeated cell infusion unless stem cells are corrected, and gene delivery must be carefully controlled.

How to write this in exams

  1. 1

    Start with the exact idea

    Gene therapy is a biotechnological approach in which a functional gene is introduced into a person's cells to compensate for a defective or missing gene responsible for a disorder.

  2. 2

    Then show how to use it

    Name the disorder, identify the defective gene or missing enzyme, state whether the method is ex-vivo or in-vivo, describe gene delivery using a vector, explain return or expression in cells, and mention limitation if asked.

  3. 3

    Add one concrete example

    In ADA deficiency, lymphocytes can be taken from the patient, cultured, supplied with a functional ADA gene using a vector, and returned to the patient's body to provide temporary immune support.

  4. 4

    Avoid this incomplete answer

    Gene therapy means replacing every defective gene in every body cell at once.

Definition

Gene therapy is a biotechnological approach in which a functional gene is introduced into a person's cells to compensate for a defective or missing gene responsible for a disorder.

Example

In ADA deficiency, lymphocytes can be taken from the patient, cultured, supplied with a functional ADA gene using a vector, and returned to the patient's body to provide temporary immune support.

Rule to remember

Key biological rule: gene therapy works by adding a functional gene copy to restore or improve production of a missing protein, but success depends on delivery, expression, and cell survival.

Memory hook

Gene therapy: give the cell a working instruction copy.

Examples and method

Worked example

Question: Explain ex-vivo gene therapy for ADA deficiency. Answer: Lymphocytes are taken from the patient and grown in culture. A functional ADA gene is introduced using a vector. The genetically corrected lymphocytes are returned to the patient, where they produce ADA for a limited period.

Method to apply

Name the disorder, identify the defective gene or missing enzyme, state whether the method is ex-vivo or in-vivo, describe gene delivery using a vector, explain return or expression in cells, and mention limitation if asked.

Diagram support

A useful diagram can show ex-vivo therapy: patient cells removed, functional gene inserted with vector, corrected cells cultured, and cells returned. Labels: patient lymphocyte, ADA gene, vector, corrected cell, reinfusion.

How CBSE asks it

Asked as a short answer on ADA deficiency, an assertion-reason question on temporary treatment, or a comparison between ex-vivo and in-vivo gene therapy.

Avoid common mistakes

Common confusion

Students often write that gene therapy always gives a permanent cure. Some approaches are temporary unless long-lived stem cells are corrected successfully.

Common wrong answer

Gene therapy means replacing every defective gene in every body cell at once.

Exam tip

For ADA deficiency, include defective gene, missing enzyme, patient lymphocytes, vector-mediated gene insertion, and return of corrected cells.

Quick check

Why may gene therapy for ADA deficiency need repeated treatment when lymphocytes are used?

Lymphocytes have a limited life span, so corrected lymphocytes may not remain in the body permanently. Repeated infusion may be needed unless the functional gene is introduced into long-lived stem cells.

Answer writing and exam use

1-mark answer

Define gene therapy, name ADA deficiency, describe the ex-vivo sequence, mention functional ADA gene and vector, then add why repeated treatment may be required.

2-mark answer

Define gene therapy, name ADA deficiency, describe the ex-vivo sequence, mention functional ADA gene and vector, then add why repeated treatment may be required.

3-mark answer

Define gene therapy, name ADA deficiency, describe the ex-vivo sequence, mention functional ADA gene and vector, then add why repeated treatment may be required.
Practice

Concept practice is coming soon

Join the waitlist for concept-level MCQs and weak-concept practice.

10 MCQs5 MinutesInstant Results
Join Waitlist for Practice

Help improve this page

Found something confusing, incorrect, or missing?

Open Learning Map