1. Gene Therapy

2. What is gene therapy?
It’s an experimental science used to help treat and prevent diseases by introducing DNA/RNA into a person’s cells.
Approaches
-Turning off mutated genes
-Make diseased cells more evident so that immune sys’t will recognize them as intruders and attack
-Replacing missing or mutated genes

3. How do genes get delivered into a cell?
Vectors: viruses
-in vivo and ex vivo
Types of viruses
retroviruses
Adenoviruses
Adeno-associated viruses

4. Non-viral gene delivery
Direct intro of therapeutic DNA into target cell, however it’s limited to certain tissues
Chemically linking DNA to a molecule that will bind to special cell receptors
Experimenting with intro of 47th chromosome into target cell. It would be a large vector carrying large amount of genetic code

5. Current Status of Gene Therapy
Available in clinical trials
1999-suffered major setback with the death of 18 yr.old Jesse Gelsinger
He was participating in a trial for ornithine transcarboxylase deficiency (OTCD).
Died from multiple organ failures believed to be triggered by immune response to adenovirus carrier

6. Cont’d
In 2003 the FDA placed a temporary halt on gene therapy trials using retroviral vectors in blood stem cells
The 2nd child treated in a French gene therapy trial had developed leukemia like symptoms
Treated for X-linked combined immunodeficiency disease (X-SCID) known as “bubble baby syndrome”

7. Risks Immune response to newly introduced viruses
Possibility that once inside the body viruses may recover ability to cause disease
Gene therapy considered short-lived
target cells must remain functional
Cells containing therapeutic DNA must be stable
Difficulty treating diseases caused by the combined effects of variations in genes

8. Ethical Considerations
Who decides which traits are normal and which constitute as a disability or disorder
Is somatic gene therapy is more or less ethical than germ-line therapy?
Religious view:
Is it right to manipulate genes as if playing God?
Science is a response to proper human activity reflecting in some part God’s wisdom and creativity

9. Somatic Gene Therapy
Directed at the body’s non-reproductive cells and only affects the genetic makeup of one person
Few ethical considerations

10. Germ-line Gene Therapy
Targets egg and sperm cells, therefore the insertion of the gene passes on to next generation
Genetic modification of early embryos-
Those who think early embryos are like a human person say NO to germ-line
Those who think that in later development human acquire trait that make them human subjects say YES to germ-line

11. Other Considerations Possibility for genetic enhancement
Gene therapy is expensive and its use with IVF makes it unlikely that the costs will be covered by insurance companies, thus making people of means have better access

12. My Opinion !
May be the only way to treat certain problems Ex: treat genetically determined tumors like retinoblastoma
“Far more efficient to cure a genetic disease with a single treatment that will prevent its appearance in future generations, than to treat the disease each time it appears, generation after generation”
Conserves future health care resources