Genetic therapies

Question 1

What are the two main approaches to genetic therapy (for a loss of function mutation) and what is the main one that is used?

Answer 1

Gene augmentation (mainly used)
- involves leaving the mutated gene and instead just adding an additional functional gene

Gene replacement
- involves removal of the non functioning gene and replacing with a functional gene. This is often needed if the mutated gene has a dominant effect.

Question 2

What does gene therapy involve and what cells are targeted?

Answer 2

It involves the insertion of DNA or RNA into the cells.

It is only done in somatic cells (not germline cells).

Question 3

What are some gene delivery strategies?

Answer 3

Ex vivo
- the cells are removed from the body and manipulated in the laboratory and returned to the patient

or

In vivo
- the cells remain inside the patient and the therapy then needs to be able to target specific cells

In both cases the methods are:
- Physical (electorporation - drilling holes in the cell wall so DNA can enter, microinjection - inject DNA directly into the cell, or lipofection - genes in lipid bound vesicles fuse with the cell)

• Viral (retovirus = insert DNA into a viral vector which will then bind to cell walls and once inside the cell the vescile ruptures and releases the DNA so it can be taken uo).