Gene Therapy

Question 1

What is gene therapy?

Answer 1

• Treating disease (genetic) by altering natural genotype.

Question 2

Potential problems of using viruses as gene vectors.

Answer 2

• They may stimulate an immune/inflammatory response in the patient.
• The patient might then become immune to virus, so it can’t be used again in the future to deliver that allele.
• The virus would mutate and become pathogenic.

Question 3

Semantic gene therapy.

Answer 3

• Involves altering the alleles in normal body cells, in specific cells affected by disorder e.g. with C, it is the cells lining the airways that are targeted and genetically modified.
• This type of gene therapy does not affect the sex cells nor the zygote/embryo, so cannot be passed onto offspring.

Question 4

Germ line therapy

Answer 4

• Involves altering the alleles in the sex cells/gametes/embryo, which means that all of the cells in the offspring would have the genetic modification - it is passed onto to offspring . This is possible, but illegal.

Question 5

Why is germ line banned in humans?

Answer 5

• The potential impact on the resulting offspring is unknown.
• Concerns regarding “human rights” of unborn offspring - no consent given.
• Irreversible.
• Could enable people to choose “desirable characteristics” for their unborn children.

Question 6

Why is somantic gene therapy only temporary cure for disease?

Answer 6

• The newly inserted “correct” allele will be passed on every time the cell divides by mitosis, but somantic cels have limited lifespan.
• They have to be replaced by stem cells, so after a while, this is expressed again.

Question 7

Positives and negative of gene therapy.

Answer 7

Positives:
- prolonged life expectancy.
- Better quality of life.
Negative:
- Very expensive.
- Effects only short.