Gene Therapy

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Transcript Gene Therapy

Gene Therapy
What is Gene Therapy?
Gene Therapy is the insertion of genes into an
individual’s cells and tissues to treat a disease.
This technology is still being experimented with
today, but it has been used with some success.
How Does Gene Therapy Work?
There are many different ways of correcting faulty genes:
A normal gene is inserted into a nonspecific location in the
genome to replace a nonfunctional gene, this is the most
common method.
An abnormal gene could be swapped for a normal gene
through homologous recombination
The abnormal gene could be repaired through selective
reverse mutation, which returns the gene to its normal
The regulation of a particular gene( whether a gene is
turned on or off) could be altered
How Does Gene Therapy Work?
The Basic Process:
A gene that is inserted directly into the cell usually will not function.
Carrier molecules called vectors are genetically engineered to deliver
the genes. Viruses are often used as vectors because they can deliver
the new gene by infecting the cell. The viruses are modified so they do
not cause disease when used in humans.
A vector can be injected or given intravenously, directly into a specific
tissue in the body, where it is taken up by individual cells. Also, a
sample of the patient’s cells can be removed and exposed to the vector
in a laboratory. The cells containing the vector are then returned to the
patient. If the treatment is successful the new gene delivered by the
vector will make a functioning protein.
Diagram of Gene Therapy
The Applications of Gene Therapy
When genes have been safely transferred and are being expressed
their activity typically falls off after a short time. Because of this,
trials now under way in humans are not aimed at correcting
genetic defects; instead researchers are looking for ways to use
gene therapy to counter major killers such as heart disease and
cancer. In these cases a short period of activity by the
transferred gene is not only sufficient but desirable. One
application is to help treat coronary heart disease by introducing
a gene encoding a growth factor that stimulates new blood
vessels to grow around blocked arteries into the heart muscle.
The goal is to get the heart cells to produce enough growth
factor to trigger a brief period of blood vessel growth.
The Heart
The Benefits of Gene Therapy
Gene therapy may someday be used to treat a variety of diseases
Gene therapy can provide ‘patient-friendly’ treatment regimens
for a variety of diseases. Today many patients with hemophilia
and diabetes must have repeated injections in order to manage
their disease because proteins exist in the blood stream for a
limited amount of time before they are degraded. Since DNA is
more stable and functions inside the cell, the delivery of genes
may result in longer-term expression of the proteins.
Because gene therapy is accurate it has the potential to eliminate
cancer cells without damaging normal, healthy tissue.
Gene therapies may provide alternatives when a disease does not
respond to other treatments.
Ethical Issues
What is considered normal and what is considered a disability or
disorder, and who decides?
Are disabilities diseases? Do they need to be cured or prevented?
Does searching for a cure demean the lives of individuals
currently affected by disabilities?
Preliminary attempts at gene therapy are extremely expensive.
Who will have access to these therapies? Who will pay for their
Gene therapy may someday have the potential of allowing
parents to choose the genes their children receive, is this ethical?
Biology Concepts and Connections, Fourth Edition, AP Biology Textbook