gene therapy

what is gene therapy?

insertion of genes into an individual’s cells to treat inherited disease

what are the two processes involved in gene therapy?

• replacement of faulty gene w/ normal gene

• addition of normal gene to supplement faulty gene

name and define the 3 types of gene therapy:

• somatic cell therapy - treating adult body cells

• germ cell therapy - treating egg/sperm cells

• stem cell therapy - treatment of stem cells

describe somatic cell therapy:

• insertion of copies of functional gene into somatic cells

• has been used to treat blood disorders and CF

describe germ cell therapy:

• insertion of copies of functional gene that has been fertilised using IVF

• embryo allowed to develop before re-implanted

• successful gene transfer will mean every cell contains corrected gene and will be passed onto offspring

• currently illegal in humans due to the risks of designer babies

describe stem cell therapy:

• insertion of copies of functional gene into stem cells e.g. into bone marrow

• all WBCs will contain inserted gene

• long term treatment for blood diseases

describe the process of gene therapy:

• extraction of cells

• use virus as vector as can insert DNA into cells

• modify virus so cannot reproduce/cause diseases

• insert functional gene into virus

• virus placed in culture w/ cells, delivering gene into cells (BUT has low success rate)

• GMed cells injected back into patient

name 3 types of vector that may be used in gene therapy:

• retroviral vector

• adenoviral vector

• nonviral vector

give 4 advantages of gene therapy:

• can prolong lives of those suffering from genetic disorders/cancer

• better QoL for those w/ disorders/cancers

• genetic disorder carriers can have children w/o risk of gene being inherited

• germ therapy decreases no. of people w/ genetic disorders

give 7 disadvantages of gene therapy:

• somatic cell therapy short lives

• stem cell therapy requires multiple treatments

• diff to insert allele into specific cell

• vectors used to carry disease may be rejected

• allele could be inserted into wrong place

• inserted alleles could be over-expressed so too much of protein produced

• diff to treat genetic disorders caused by multiple genes