gene therapy

Question 1

Define Gene Therapy

Answer 1

Any procedure intended to treat or alleviate disease by genetically modifying the cells of the patient

Question 2

Name 4 types of disorders gene therapy can treat

Answer 2

Inherited diseases
Cancers
Infectious disease
Immune disorders

Question 3

Name the two broad categories of gene therapy

Answer 3

Germline cell modification

Somatic cell modification

Question 4

What is Germ-line cell genetic modification?

Answer 4

Permanent modifications transmitted to descendants. Achieved by modifying DNA of a gamete/zygote or early embryo

Question 5

Is Germ-line cell modifications allowed in humans?

Answer 5

NO

Question 6

Can somatic cell genetic modification be passed on?

Answer 6

no

Question 7

What are the two strategies to somatic cell gene therapy?

Answer 7

Modify the disease cell to alleviate the disease

Selectively kill the diseased cell

Question 8

Name how disease cells can be modified to alleviate the disease

Answer 8

gene augmentation
gene silencing
repair of the mutant gene

Question 9

What is gene augmentation?

Answer 9

Adding functional copies of the gene back into cells that lack them.

Question 10

What is gene silencing?

Answer 10

Expression of a gene is selectively inhibited by turning off transcription

Question 11

Describe how to selectively kill diseased cells

Answer 11

Directly kill with targeting cells eg suicide gene
Or indirectly ( assisted killing) by modifying the immune system to enhance response to disease cell and initiate cell death. Uses Prodrug

Question 12

What is the difference between In-vivo and ex-vivo gene transfer?

Answer 12

In-vivo= direct delivery
Ex-vivo= cell based delivery

Question 13

What are the issues with short lived cells

Answer 13

Cells need to divide to replenish lost cells so gene therapy genetic material might not be passed into newly divided cells

Question 14

What 4 things does gene transfer need to meet?

Answer 14

Non toxic
Target the DNA to a particular cell
Introduce DNA into a cell in a transcriptionally active form
Express the gene at a reasonable level for sufficient time

Question 15

Name a non viral delivery vehicle

Answer 15

Liposome

Question 16

Name 4 viral delivery vehicles

Answer 16

Retrovirus
Lentivirus
Adenovirus
Adeno-associated viruses

Question 17

Describe how liposomes are delivery vehicles

Answer 17

Liposome contains genetic information
Taken up via endocytosis or clathrin coated pits
Taken into nucleus for gene to be expressed

Question 18

What is the gene placed in to achieve high levels of expression?

Answer 18

Plasmid expression vector

Question 19

Name the common expression vector

Answer 19

pJ7 omega

Question 20

Name the parts of the expression vector

Answer 20

Polyadenylation site 
Splice donor site
Splice Acceptor site
CMV promoter
cloning sites

Question 21

What is the role of the polyadenylation site?

Answer 21

Efficient termination of transcription in the expression vector

Question 22

What is the role of the CMV promoter?

Answer 22

Drives transcription, strongest promoter, works in all eukaryotic cells

Question 23

What happens to the expression vector in nucleus of patient cell?

Answer 23

RNA polymerase binds CMV and transcribes RNA

RNA cleaved and polyadenylated then spliced

Question 24

Why is plasmid inefficiently transported into the nucleus?

Answer 24

Due to its large size it cannot always enter through the nuclear pores

Question 25

What are the two approaches that can get the plasmid DNA into the nucleus

Answer 25

COnjugating specific DNA or protein sequencing

Compact the DNA

Question 26

How many people does Cystic Fibrosis affect?

Answer 26

1/2500

Question 27

What causes Cystic Fibrosis?

Answer 27

Defective CFTR gene, which encodes for a Cl- ion trasnporter

Question 28

Name the main advantage of liposomes?

Answer 28

Non-toxic

Question 29

What are the disadvantages of lipsomes?

Answer 29

Inefficient transfer of DNA to target cells
Cannot target particular cell types
Poor expression