1. Define gene therapy and explain its primary goal.
Answer: Gene therapy is a medical technique that involves modifying or manipulating genes within an individual’s cells to treat or prevent disease. Its primary goal is to replace defective or missing genes with functional ones, repair faulty genes, or alter gene expression to address the root causes of genetic disorders.
2. What are the main types of gene therapy, and how do they differ?
Answer: The main types of gene therapy are:
Somatic gene therapy: Targets non-reproductive cells, and the changes affect only the treated individual without being inherited by offspring.
Germline gene therapy: Involves modifying genes in reproductive cells (sperm or eggs) or embryos, resulting in heritable changes that can be passed to future generations.
3. Describe the role of vectors in gene therapy.
Answer: Vectors are carriers used to deliver therapeutic genes into target cells. Common vectors include viruses (e.g., retroviruses, adenoviruses, lentiviruses) and non-viral methods like liposomes and nanoparticles. Vectors ensure efficient delivery and integration of the gene into the host genome.
4. What is the difference between in vivo and ex vivo gene therapy?
Answer:
- In vivo gene therapy: Genes are delivered directly into the patient’s body, targeting the affected cells or tissues.
- Ex vivo gene therapy: Cells are removed from the patient, genetically modified in a laboratory, and then reintroduced into the body.
5. Explain how CRISPR-Cas9 technology is utilized in gene therapy.
Answer: CRISPR-Cas9 is a genome-editing tool that allows precise cutting and modification of DNA sequences. In gene therapy, it can be used to:
- Correct genetic mutations.
- Insert functional genes.
- Remove faulty or disease-causing genes. This technology has revolutionized gene therapy due to its accuracy and efficiency.
6. Discuss the ethical considerations associated with germline gene therapy.
Answer: Germline gene therapy raises ethical concerns because:
- It involves heritable genetic changes that may impact future generations.
- There is potential for unintended consequences or “off-target” effects.
- It could lead to “designer babies” or genetic enhancement. Ethical guidelines stress caution and emphasize the need for societal consensus and regulation.
7. What are the risks and limitations of viral vectors in gene therapy?
Answer: Risks and limitations include:
- Immune response to viral proteins.
- Potential insertional mutagenesis, which may lead to cancer.
- Limited capacity for carrying large genes.
- High production costs and technical challenges.
8. Provide an example of a disease successfully treated by gene therapy.
Answer: Severe Combined Immunodeficiency (SCID) has been successfully treated using gene therapy. By introducing a functional copy of the defective gene into bone marrow stem cells, patients have shown improved immune function and reduced dependence on regular treatments.
9. What are the major challenges in developing effective gene therapy treatments?
Answer: Challenges include:
- Efficient and safe delivery of genes to target cells.
- Avoiding immune reactions.
- Ensuring long-term gene expression.
- Addressing ethical and regulatory concerns.
- High costs and limited accessibility.
10. How does gene silencing differ from traditional gene therapy approaches?
Answer: Gene silencing involves suppressing the expression of a specific gene, often using RNA interference (RNAi) or antisense oligonucleotides. Traditional gene therapy, on the other hand, focuses on replacing or repairing defective genes to restore their function.
11. Explain the role of liposomes as non-viral vectors in gene therapy.
Answer: Liposomes are spherical vesicles made of lipid bilayers that can encapsulate therapeutic DNA or RNA. They serve as non-viral vectors, offering:
- Reduced risk of immune response.
- Protection of genetic material from degradation.
- Flexibility in delivering large or multiple genes.
12. Describe the “knock-in” approach in gene therapy.
Answer: The “knock-in” approach involves inserting a functional gene into a specific location within the genome to replace or supplement a defective gene. This technique ensures controlled expression and minimizes the risk of disrupting other genes.
13. What is the significance of clinical trials in gene therapy?
Answer: Clinical trials are essential for:
- Evaluating the safety and efficacy of gene therapy treatments.
- Identifying potential side effects and risks.
- Optimizing delivery methods and protocols.
- Gaining regulatory approval for widespread use.
14. How is gene therapy used in the treatment of cancer?
Answer: Gene therapy can treat cancer by:
- Introducing genes that induce cancer cell death (e.g., suicide genes).
- Enhancing immune system response (e.g., CAR-T cell therapy).
- Silencing oncogenes or repairing tumor suppressor genes.
15. Discuss the concept of “off-target effects” in gene therapy.
Answer: “Off-target effects” refer to unintended modifications in non-target DNA sequences during gene editing. These effects can:
- Cause genetic instability.
- Lead to unintended health issues, such as cancer.
- Reduce the specificity and safety of gene therapy. Minimizing off-target effects is a critical area of research.
16. What are the regulatory challenges in approving gene therapy treatments?
Answer: Regulatory challenges include:
- Establishing long-term safety and efficacy.
- Addressing ethical and societal concerns.
- Developing standardized guidelines for clinical trials.
- Balancing innovation with public health safety.
17. How does Severe Combined Immunodeficiency (SCID) exemplify gene therapy’s potential?
Answer: SCID is caused by genetic mutations leading to a dysfunctional immune system. Gene therapy involves:
- Extracting hematopoietic stem cells from the patient.
- Inserting a functional copy of the defective gene.
- Reintroducing the modified cells into the patient’s body. This approach has restored immune function in several patients.
18. What are the ethical arguments for and against somatic gene therapy?
Answer: For:
- Treats severe diseases, improving quality of life.
- Limited to the individual, avoiding heritable changes. Against:
- High costs may limit accessibility.
- Risk of unforeseen side effects and complications.
19. Explain the concept of “gene doping” and its ethical implications.
Answer: Gene doping refers to the use of gene therapy techniques to enhance athletic performance. Ethical implications include:
- Undermining fair competition.
- Health risks associated with unregulated use.
- Detracting from the original purpose of gene therapy.
20. How can bioethics guide the responsible use of gene therapy?
Answer: Bioethics provides a framework to:
- Balance innovation with safety and fairness.
- Address societal concerns about accessibility and equity.
- Develop guidelines for ethical research and clinical application.
- Promote transparency and public engagement.
