[W8] Gene Therapy Flashcards
(30 cards)
What is gene therapy?
Replacement or repair of defective genes to treat or prevent disease.
What is the broader definition of gene therapy?
Treatment of genetic disorders by modifying human body cells.
What is gene editing?
Precise alteration (insertion, deletion, or replacement) of DNA using engineered nucleases.
What is the difference between gene therapy and gene editing?
Gene therapy replaces an entire gene; gene editing targets specific regions within genes.
What factors influence gene therapy success?
- Disease’s genetic basis
- Target tissue/cell type
- Delivery route
- Expression duration
- Gene regulation
- Cell/tissue specificity
What must a therapeutic gene achieve in cells?
Correct timing and level of expression in the right target cells.
Which disease type is most commonly targeted by gene therapy?
Cancer.
Are many diseases linked to single genes?
No, most have complex or multiple genetic components.
What are the two main categories of gene delivery methods?
- Viral-mediated delivery (~75%)
- Non-viral-mediated delivery (~25%)
What factors influence the choice of delivery method?
- Delivery efficiency
- Gene size
- Duration of expression
- Safety profile
What is a replication-deficient virus?
A virus modified to remove genes for replication/pathogenicity.
Why is viral tropism useful in gene therapy?
It allows targeting of specific tissues/organs.
What is a risk of using viral vectors?
Reversion to wild-type virus or off-target effects.
What is naked DNA delivery?
Direct injection of DNA (e.g., into muscle); low efficiency, rapidly degraded systemically.
What are liposomes?
Lipid-based carriers for DNA/mRNA delivery; safe but inefficient and rapidly cleared.
What are the challenges of non-viral delivery?
- Cell entry
- Nuclear transport
- Efficient transcription
How do adenovirus-based vaccines work?
Deliver the gene for an antigen (e.g., SARS-CoV-2 spike protein) into host cells for expression.
How do liposome-based mRNA vaccines work?
Deliver mRNA encoding spike protein into the cytoplasm; no need for nuclear entry.
What is CAR-T cell therapy?
A gene therapy where a patient’s T-cells are modified to express chimeric antigen receptors (CARs) that target cancer cells.
Name three genome editing systems.
- Zinc Finger Nucleases (ZFNs)
- TALENs
- CRISPR-Cas9
What are the two approaches to genome editing?
- Protein-based
- RNA-based
What is CRISPR?
A prokaryotic immune mechanism using guide RNA and Cas9 nuclease to target and cut specific DNA sequences.
What does Cas9 do?
It is an endonuclease that creates double-stranded breaks at target DNA sites guided by RNA.
What is a PAM sequence?
A short DNA motif required for Cas9 to bind and cleave target DNA.
