Gene therapy MCQs With Answer

Gene therapy MCQs With Answer

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Introduction: Gene therapy MCQs With Answer is a focused question bank tailored for M.Pharm students studying Advanced Pharmaceutical Biotechnology. This resource covers core concepts such as viral and non‑viral vectors, gene editing tools (CRISPR/Cas, TALENs, ZFNs), ex vivo and in vivo delivery strategies, pharmacokinetics of gene products, immunogenicity, safety concerns like insertional mutagenesis, and regulatory/manufacturing considerations for clinical translation. Each question emphasizes mechanistic understanding, vector biology, delivery challenges, and real‑world therapeutic design to prepare students for exams and research. Answers are provided to reinforce learning and enable targeted review of complex gene therapy topics.

Q1. What characteristic of adeno-associated virus (AAV) vectors most contributes to their favorable safety profile in clinical gene therapy?

  • High cargo capacity (>10 kb)
  • Strong innate immune activation
  • Predominantly episomal persistence with low integration frequency
  • Broad ability to integrate into the host genome at random sites

Correct Answer: Predominantly episomal persistence with low integration frequency

Q2. Which DNA repair pathway is primarily exploited to achieve precise gene correction using homology-directed repair (HDR) after a CRISPR/Cas9-induced double-strand break?

  • Non-homologous end joining (NHEJ)
  • Base excision repair (BER)
  • Homology-directed repair (HDR)
  • Nucleotide excision repair (NER)

Correct Answer: Homology-directed repair (HDR)

Q3. For ex vivo gene therapy of hematopoietic stem cells (HSCs), which vector property is most critical to achieve long-term therapeutic expression?

  • Transient episomal expression
  • Integrating capability into long-lived stem cell genomes
  • High innate immune stimulation to select modified cells
  • Large particle size to increase tissue retention

Correct Answer: Integrating capability into long-lived stem cell genomes

Q4. Which of the following is the primary safety concern associated with the use of integrating gamma-retroviral vectors in early gene therapy trials?

  • Excessively low expression of therapeutic gene
  • Insertional activation of proto-oncogenes leading to leukemia
  • Rapid episomal loss in dividing cells
  • Severe neutralizing antibody formation preventing re-dosing

Correct Answer: Insertional activation of proto-oncogenes leading to leukemia

Q5. Which non-viral delivery system is most commonly used for mRNA-based gene therapies and vaccines due to efficient cellular uptake and endosomal escape?

  • Cationic lipids forming lipid nanoparticles (LNPs)
  • Plasmid DNA precipitates
  • Polyethylene glycol (PEG) alone
  • Gold nanoparticle aggregates without surface modification

Correct Answer: Cationic lipids forming lipid nanoparticles (LNPs)

Q6. In AAV vector design, which sequence element is essential for efficient transcriptional control of the transgene in a tissue-specific manner?

  • Inverted terminal repeats (ITRs) only
  • Tissue-specific promoter upstream of the transgene
  • Random bacterial promoter sequences
  • Polyadenylation signal located thousands of bases downstream

Correct Answer: Tissue-specific promoter upstream of the transgene

Q7. Which statement best contrasts lentiviral vectors with adenoviral vectors in gene therapy?

  • Lentiviral vectors are non-integrating and elicit strong innate immunity
  • Adenoviral vectors integrate into host DNA preferentially and give stable expression
  • Lentiviral vectors integrate into dividing and non-dividing cells providing stable expression
  • Adenoviral vectors have unlimited cargo capacity for very large genes

Correct Answer: Lentiviral vectors integrate into dividing and non-dividing cells providing stable expression

Q8. Which mechanism primarily underlies off-target effects in CRISPR/Cas9 genome editing?

  • Homology-directed repair accuracy
  • Imprecise guide RNA binding to near-match genomic sites leading to unintended cuts
  • Excessive promoter activity of the delivery vector
  • Rapid degradation of Cas9 protein preventing on-target activity

Correct Answer: Imprecise guide RNA binding to near-match genomic sites leading to unintended cuts

Q9. Which pharmacokinetic parameter is most relevant when assessing biodistribution of a systemically delivered viral vector?

  • Half-life of the free drug in plasma only
  • Vector tropism and organ-specific transduction efficiency
  • MIC (minimum inhibitory concentration)
  • Renal clearance of small-molecule metabolites

Correct Answer: Vector tropism and organ-specific transduction efficiency

Q10. What advantage does self-inactivating (SIN) design confer to integrating lentiviral vectors?

  • Enhances replication competence of the vector
  • Reduces promoter/enhancer-mediated activation of adjacent host genes
  • Increases vector genome size capacity to >20 kb
  • Eliminates requirement for packaging signals

Correct Answer: Reduces promoter/enhancer-mediated activation of adjacent host genes

Q11. In gene therapy manufacturing, why is adherence to Good Manufacturing Practice (GMP) critical for clinical-grade viral vector production?

  • It is optional for academic studies only
  • GMP ensures product consistency, purity, safety and traceability for patient use
  • GMP focuses solely on lowering production costs
  • GMP mandates the use of only bacterial hosts for vector production

Correct Answer: GMP ensures product consistency, purity, safety and traceability for patient use

Q12. Which approach is most appropriate to reduce immune neutralization of viral vectors upon systemic re-administration?

  • Use of the identical serotype repeatedly
  • Transient immunosuppression or switching to an alternative serotype/capsid
  • Increasing vector dose linearly without modification
  • Avoiding capsid engineering to preserve wild-type antigenicity

Correct Answer: Transient immunosuppression or switching to an alternative serotype/capsid

Q13. Which clinical application exemplifies in vivo gene therapy?

  • Ex vivo modification of T cells to express CAR and reinfusion
  • Intramuscular injection of AAV encoding a missing enzyme to correct a metabolic disorder
  • Bone marrow transplantation without genetic modification
  • Topical application of small-molecule antibiotics

Correct Answer: Intramuscular injection of AAV encoding a missing enzyme to correct a metabolic disorder

Q14. Which regulatory element in a gene therapy cassette improves mRNA stability and translation efficiency in mammalian cells?

  • Prokaryotic origin of replication
  • Optimized 5′ untranslated region (UTR) and Kozak sequence plus poly(A) signal
  • Lack of polyadenylation signal
  • Random bacterial promoter sequences

Correct Answer: Optimized 5′ untranslated region (UTR) and Kozak sequence plus poly(A) signal

Q15. Which of the following best describes the therapeutic modality of RNA interference (RNAi) compared with classical gene replacement therapy?

  • RNAi provides permanent genomic insertion of a corrective gene
  • RNAi transiently reduces expression of a target mRNA but does not replace a missing protein
  • RNAi increases protein expression by integrating promoter constructs
  • RNAi repairs DNA sequences via HDR

Correct Answer: RNAi transiently reduces expression of a target mRNA but does not replace a missing protein

Q16. In CAR-T cell therapy production, what is the primary purpose of including a safety (suicide) switch in the engineered cells?

  • To permanently enhance CAR-T persistence regardless of toxicity
  • To enable controlled elimination of CAR-T cells in case of severe adverse events
  • To increase the proliferation rate of CAR-T cells in vivo
  • To prevent any expression of the CAR at baseline

Correct Answer: To enable controlled elimination of CAR-T cells in case of severe adverse events

Q17. Which analytical assay is most appropriate to quantify vector copy number (VCN) in transduced cell products?

  • Western blot for capsid proteins
  • Quantitative PCR (qPCR) targeting vector-specific sequences normalized to a housekeeping gene
  • Standard bacterial colony counts
  • ELISA for immune cytokines

Correct Answer: Quantitative PCR (qPCR) targeting vector-specific sequences normalized to a housekeeping gene

Q18. For a dominant negative genetic disorder, which gene therapy strategy is generally most appropriate?

  • Simple gene addition of the wild-type gene without silencing the mutant allele
  • Allele-specific silencing (e.g., RNAi) or gene editing to disrupt the mutant allele combined with replacement
  • Administration of nonspecific immune stimulants
  • Use of episomal vectors that dilute rapidly in dividing tissues

Correct Answer: Allele-specific silencing (e.g., RNAi) or gene editing to disrupt the mutant allele combined with replacement

Q19. Which manufacturing challenge is unique to viral vector production compared with small-molecule pharmaceutical production?

  • Requirement for sterile filtration for all final products
  • Complex upstream cell culture systems, scalability limits, and need to ensure absence of replication-competent virus
  • Quantifying simple chemical impurities by HPLC only
  • Standard freeze-drying procedures always apply without optimization

Correct Answer: Complex upstream cell culture systems, scalability limits, and need to ensure absence of replication-competent virus

Q20. Which ethical/regulatory concern is especially prominent for germline gene editing compared with somatic cell gene therapy?

  • Short-term off-target effects in a single treated tissue
  • Heritable changes transmitted to future generations and associated societal implications
  • Need for GMP manufacturing standards
  • Transient expression of therapeutic protein

Correct Answer: Heritable changes transmitted to future generations and associated societal implications

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