MG (Gene Therapy)

Question 1

What’s germ line gene therapy

Answer 1

• definition: Gene therapy by inserting functional alleles into gametes or zygotes (illegal in humans)
• If successful, all cells of the embryo will contain the corrected gene when cell divides by mitosis (changes entire genetic make up)
• permanent and also ensures offspring inherit corrected gene
• descendants of patient haven’t given consent
• genes inserted may find their way into a location that could disrupt the expression or regulation of other genes or increase the risk of cancer.

Question 2

what’s somatic cell gene therapy

Answer 2

• definition : gene therapy by inserting functional alleles into body cells
• any offspring could still inherit the disease.
• has to be repeated many times as the effects do not last very long.
• Cystic fibrosis (CF) is a genetic disorder that’s very damaging to the respiratory system, so somatic therapy for CF targets the epithelial cells lining lungs.

Question 3

what’s the principle of gene therapy

Answer 3

• is to insert a functional allele of a particular gene into cells that contain only mutated and non-functioning alleles of that gene.
• If the inserted allele is expressed, then the individual will produce a functioning protein and no longer have symptoms associated with the genetic disorder.

Question 4

How are liposomes (small spheres of lipid bilayer) used as vectors

Answer 4

1. Functioning genes isolated from human cells & inserted into plasmids.
2. Plasmids extracted & wrapped in lipid molecules (forming a liposome).
3. Liposomes sprayed into patients airways via a nasal aerosol.
4. Liposomes pass easily through the plasma membrane of cells and nucleus.

Question 5

How are liposomes used to treat cystic fibrosis?

Answer 5

• alleles packaged in liposomes which are placed into inhaler and also sprayed into the nose of patient
• some pass through plasma membrane and into the nucleus through (nuclear envelope) of cells lining respiratory tract
• CFTR gene inserted into host genome and its expressed into CTRF protein (a Cl- channel)

Question 6

How are viruses used as vectors?

Answer 6

• GM virus to encase functioning allele inserted into patient
• made unable to cause disease
• can enter recipient cells

Question 7

what are potential problems of using viruses as vectors?

Answer 7

• may still cause an immune or inflammatory response in patient
• patient may become immune so subsequent deliveries are more difficult
• allele inserted into genome in a location that disrupts a gene involved in regulating cell division, increasing risk of cancer
• allele inserted in location that disrupts the the regulation of the expression of other genes

Question 8

what’s the potential of artificial chromosomes in gene therapy

Answer 8

• Research is being carried out into the possibility of inserting genes into an artificial chromosome that would co-exist with the other 46 chromosomes in the target cells.

Question 9

positives of gene therapy

Answer 9

• Could prolong the lives of people with life-threatening genetic disorders
• Could give people with genetic disorders a better quality of life if it helps to ease symptoms
• Germ line therapy would allow the carriers of genetic disorders to conceive a baby without that disorder
• Germ line therapy could decrease the number of people that suffer from genetic disorders and cancer, which is beneficial for individuals and society as a whole (fewer people will require treatment).

Question 10

Negatives of gene therapy

Answer 10

• Technology could potentially be used in ways other than for medical treatment, such as for treating the cosmetic effects of ageing.
• Concern that gene therapy is expensive - some people believe that health service resources could be better spent on other treatments that have passed clinical trials.
• Potential to do more harm than good by using the technology.