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What is this “Gene Therapy”?
How does it work?
What is its significance/benefits in society?
How is technology used in this?
What ethical issues might this involve?
What are the potential problems of this?
What is Gene Therapy?
-a simple definition by Karen Chen
Gene therapy is a relatively new technique used to treat
genetic disorders and diseases. The method is mainly used to
correct defective genes that are responsible for the
development of the disease. The most common practice of
gene therapy is to replace a mutant allele* with a functional
one.
*for definition, visit http://dictionary.reference.com/browse/allele
How Gene Therapy Works
In the majority of studies on gene therapy, an
‘abnormal’ (disease-causing) gene is replaced by a
‘normal’ one by having the therapeutic gene inserted
into the target cells of a patient. This is done by using
carrier molecules called vectors to deliver the ‘normal’
gene to where it’s needed. Believe it or not, the most
commonly used vector is a virus. Not any old virus
though, these viruses have been genetically altered to
carry normal human DNA. Nowadays, viruses have
evolved a way of taking their own genes and delivering
them to human cells to cause illness. Scientists have
been able to use this to their advantage however by
using this ability of theirs and manipulating the virus
genome to remove the disease causing genes and
insert remedial ones. If, for example, we wanted to
replace abnormal cells in the liver, we would infect the
patient’s liver cells with the viral vector. The vector will
then dump its genetic material containing the normal
human gene into the target cell. With the new
therapeutic gene, the cell will generate functional
protein which restores the cell to a normal, healthy
state. Now, would everyone please have a look at this
website:
http://www.fda.gov/fdac/features/2000/gene.html
TorontoIt seems that everyday now a
new biotechnology project
comes in and you wish you
had paid more attention in
b i o l o g y
c l a s s .
At a press conference
concerning recent
developments in gene therapy
research, a brave man dared to
ask, “How is gene therapy
significant to us?”
Dr. Peter Evans of the Gene
Therapy Research
Organization (GTRO) cleared
his voice before answering,
“Gene therapy is really an
exciting topic. It can be used
to do so much. Most
commonly, we use it to treat
genetic disorders like severe
immunodeficiencies and so on.
We’re expanding its uses all
the time though, we have
guinea pigs that were deaf
with it, and we recently had
scientists prove that gene
therapy can be used to
effectivel y treat cancer.”
“It can be used to do so much,” that quote sums it up pretty well. Upon
further research, I saw the names of disorders and diseases treatable by
gene therapy stacking up. Genetic disorders like X-SCID (severe
combined immunodeficiency) or the "bubble boy" disease, sickle cell,
myeloid blood diseases, even blindness were among a list of many others
with results in varying success. Even Alzheimer's and weight loss made
the list. For the future, gene therapy is looked at as a possible treatment
for Parkinson’s and is already on its road to becoming an effective cure
to some cancers. Ways of using gene therapy as a prevention technique
against cancer and diabetes is also being looked into. If I were to bet my
bottom dollar on how significant gene therapy is, I would; it’s just that
significant.
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however,
to be
far less
effective.
Somatic gene therapy is performed on adults who are known to have the
disease while germline therapy is done is egg and sperm cells to prevent a
Do they need to be cured or prevented?
trait from being passed down from generation to generation.
Some say: Yes, life is simply much easier without
I personally think that germline therapy is perfectly acceptable. Idealistically
Some
say:with
Everyone
and anyone
should
have access to these therapies. We are
having
to deal
a disability
and no one
should
speaking, if we prevented traits from being passed down, we could
to equal
rights
and should be able to have the therapy we need
haveall
to entitled
go through
life like
that.
eventually get rid of a disease altogether. It also feels more safe knowing
performed no matter who we are and how much money we have. The
that say:
you won’t
inherit adisability
disorder doesn’t
from your parents or that you won’t pass one
Others
No, having
government
shouldapay
for our fees, ormake
at least subsidize them. If a treatment is
on
to
your
children.
On
the
other
hand,
it
is also unfair to determine
you any
less human
and
you shouldn’t
available,
anyone
should
be able tobegoregarded
have it done, no matter their financial
something
forshould
others we
without
them
differently.
Why
try soletting
hard to
curehave the chance to make a
situation.
decisionmany
for themselves.
This would
make somatic
gene therapy more ‘fair’
disabilities
people are living
with today?
It is
since it demeaning
is your personal
but when we are born, we also have no
practically
their decision
existence.
hand in deciding what genes we want.
Others say: As much as we’d like to idealize and say that everyone should be
able to have gene therapy performed, our society simply doesn’t work that way.
It is extremely costly to have to procedure done and that kind of money is difficult
to come by. There is almost no way that a patient could have it done for free
without some serious changes like huge increases in funds or higher taxes in
countries. A potential patient would have to be very financially secure for this
treatment which unfortunately, at least for now, cannot be accessed by all.
Short-lived results of gene therapy
For gene therapy to be a permanent cure, many requirements must be met. First of
all, the therapeutic DNA introduced into target cells must remain functional and
secondly, the cells containing them must be stable and live for a long period.
Long-term benefits can be prevented from success with all the problems integrating
therapeutic
into the genome and the fact that some cells’ rapid dividing
Viral VectorDNA
Problems
nature keeps gene therapy from ‘sticking’. As a result, patients often have to
Viruses
usually
theofmost
common choice for vectors and viruses,
undergo are
several
rounds
the treatment.
although genetically altered, come with some risks. Such risks would
Multigene
Disorders
include: toxicity,
immune and inflammatory responses, and gene control
and
targeting
issues
for the patient.
there
always
the high
fear that
Many
of the most
commonly
occurringFinally,
diseases
like is
heart
disease,
blood
once
the Alzheimer's
virus has entered
patient,and
it may
recover
its ability
pressure,
disease,the
arthritis,
diabetes,
are caused
byto
thespread
effects of
disease.
variations in many different genes. The best candidates to receive gene therapy
are disorders that arise from mutations in a single gene so treating diseases like
those aforementioned would be difficult.
Immune Response
Our immune system is meant to attack foreign objects when they invade our
bodies so there is always a risk of stimulating the immune system in a manner
that would reduce the effectiveness of the treatment. And since gene therapy is
often used on a patient several times, it becomes more difficult to perform since the
immune system is especially good at responding to invaders it is familiar with.