Question

The disease Leber congenital amaurosis (LCA) caused by loss-of-function mutation of a gene called RPE65, has been treated with gene therapy by injecting recombinant AAV vectors containing a normal copy of the RPE65 gene into their retinal epithelial cells. Patients receiving this therapy:

May need to repeat the treatment as the viral DNA is degraded

May acquire detrimental mutations due to integration of the virus

Will pass the mutation to their offspring

Now have the normal RPE65 gene

Pharming refers to the use of transgenic animals and plants to produce a protein drug, such as…

GM plants that have enhanced nutritional value

The production of the blood factor antithrombin III in goat milk

The production of factor VIII protein, the blood-clotting factor, by bacteria.

A transgenic monkey model for Huntington disease

Answer 1

In the process of gene therapy the viral genome is incorporated with a gene that is used to generate a protein in patirnts who are deficit of ot due to some gentic factors.

Now considering the statements:

First statement is not right because the AAV vectors to deliver the gene have proved to be quiet stable and the effect has been observed for many years following administration .Therefore , frequent treatment is not required.

Second statement is incorrect because the AAV vectors directly introduce the gene into the nucleus and there is no integration in the chromossome.So possible muations acquired that way will be minimal.

Third staement is correct because the therapy does not compltely alter the genome of the patient so the chances of affecting the offspring is likely .The treatment only supplements for a deficit protein in the patient.

Fourth statement is not correct because the patient will not have the normal gene.The gene is mutated.Gene therapy only aims at production of the protein through genetic mechanisms , it does not make the gene normal.

Therefore, statement 3 is the right answer.

Pharming:

GM crops with increased nutritional value cannot be considered a method of pharming because it is not involved in production of drug.Can be considered as nutraceutical.

Production of blood factor from goat milk can be considered as this technique as it is of therapeutic application.

Production of clotting factors by bacteria cannot be considered because bacteria are not gnetically modified.

The monkey model does not provide with any products for therapeutic application.Therefore , it is not pharming

Therefore the answer is statement 2