1. An Overview of the curriculum module available on
Gene Therapy:
Molecular Bandage?
An Overview of the curriculum module available on
Learn.Genetics

2. What is gene therapy? A way to treat diseases caused by mutated genes
Adding a normally functioning copy of the gene(s) to enough affected cells to restore normal function.

3. Which disorders are candidates for gene therapy treatment?
Disorders due to mutations in one or more genes
Single-gene disorders are more easily treated
The responsible gene is known
Copies have been made in the laboratory
The role of the protein encoded by the gene is known
Adding a normal gene will fix the problem
The affected tissues are known and accessible

4. Hallmarks of Successful Gene Therapy
Targeting the right cells
Ensuring that the gene gets to the affected cells
Activating the gene
The gene must get into the cells’ nuclei
The gene must be “turned on”; i.e., transcription and translation must take place at the correct time
Integrating the gene into the cells
DNA is integrated into the cells’ chromosomes or otherwise survives in the nucleus
Avoiding harmful side effects
The gene delivery vehicle must not trigger an immune response

5. How do you do gene therapy?
Identify the gene responsible for the disorder
Make copies of the normal gene
Insert the copies into vectors (such as viruses)
Remove the viral DNA
Insert the gene of interest
“Infect” the affected cells with the vector
The normal gene is carried into the nucleus
The DNA may integrate into the genome
Activate the gene
Transcription and translation takes place

6. Critical factors in choosing a vector
Gene size
Most vectors have an upper limit on the number of base pairs they can hold
Target tissue
Some vectors only infect a particular type of cell
Other vectors can be engineered to infect a particular type of cell
Integration into the genome
Vectors that do not lead to genome integration have a short-lived effect
Vectors that integrate into the genome or are copied along with the genome have a long-lasting effect
Vectors that lead to random integration may disrupt other genes leading to negative side-effects

7. Ways to Deliver Genes In Vivo Ex Vivo
Inject the vector directly into the desired cells in the body
Ex Vivo
Isolate the desired cells from the body
Culture the cells in a Petri dish in the laboratory
Deliver the genes to the cells using a vector
Activate the genes and make sure they have integrated properly
Return the modified cells to the body

8. Challenges in Gene Therapy
Gene delivery and activation
Genes must be delivered to a large number of cells (several million) of the affected tissue
The genes must be activated for transcription and translation to take place
Introducing changes into the germline
Not causing changes in sperm or eggs, if this is not desired
Triggering an immune response
Can be fatal
Disrupting genes in the target cells
Can cause other diseases or problems

9. Gene Therapy Successes & Failures

10. Ethical and Social Issues
Patient safety while participating in clinical trials
Which applications are therapies and which are enhancements?
“Designer” babies
Effects on future generations if germline cells are allowed to be altered
Access to gene therapies

11. Gene Therapy Module on Learn.Genetics:
Tools of the Trade
Space Doctor
Cystic Fibrosis Case Study

12. Vector Selector You are a researcher at Advanced Bio Delivery Systems
Supplies gene therapy vectors
Marketing department requests your assistance
Want to sell ABDS vectors to biotech companies pursuing specific gene therapies
Your job:
Research disorders these companies are targeting
Decide on the vector that you think will work the best

13. Vector Selector Key issues in deciding which vector to select:
Size of the gene
Will the replacement gene fit into the vector?
Tissue type
Does the vector naturally target, or can it be engineered to target, the appropriate type of cells?
Cell cycle stage (dividing vs. non-dividing)
Are the cells at the right stage of the cell cycle for the vector to “infect” them?

14. Vector Selector Read the situation assigned to your group
Decide on the best vector to use for that disease
Use the Vector Types Table as a reference to assist in making your decision
Select a reporter who will report:
The disease
The vector you selected
The reasons why you thought this was the best vector for the job