Gene Therapy
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
How do genes get delivered into a cell? Vectors: viruses -in vivo and ex vivo Types of viruses retroviruses Adenoviruses Adeno-associated viruses
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
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
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”
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
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
Somatic Gene Therapy Directed at the body’s non-reproductive cells and only affects the genetic makeup of one person Few ethical considerations
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
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
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