Q32

Criteria	Marks
Briefly outlines a named disease potentially treatable by gene therapy; details the technology; considers advantages and disadvantages; and judges its potential. The source assigns 4 if process detail is lacking.	4–5
Provides three of the above, or four with less detail.	3
Provides two of the above, or three with less detail.	2
Provides some information about the process.	1

Sample answer:

One example of gene therapy is as a treatment for cystic fibrosis. Sufferers lack a gene which makes an enzyme which plays a role in the transfer of materials across membranes. As a result they get a build up of mucus in the lungs. This technology uses an adenovirus vector to carry the gene to the cells lining the lungs. They are then able to make the necessary enzyme and the main symptom is relieved. Problems with the immune response against the vector, and little success with other vectors mean that this particular application has currently had limited impact. In the future, however, as techniques improve there is great potential in techniques of this sort to treat a range of genetic caused diseases.