Gene Therapy
Many diseases seen today are the result of a defective gene in the DNA of
the
patient and can not be cured using the traditional methods such as
antibiotics
and antiviral medication. The victims are now looking to gene
therapy as a
potential cure for their problems. Bob Williamson introduces us
the concept,
procedures, and problems associated with gene therapy in his
article, "Gene
Therapy". Along with the appearance of the recombinant DNA
technology, it
becomes possible for human beings to isolate, study, and
change gene in the
laboratory. Gene Therapy is the process of replacing a
defective gene inside a
patient’s DNA with a working gene that will produce
the correct gene products.
The genetic diseases "in which a single known
gene does not function
properly", such as sickle cell anaemia, thalassaemia
and Lesch-Nyhan syndrome,
are most suitable to be treated with the gene
therapy. There are two types of
gene therapy in curing these diseases,
patient therapy and embryo therapy. In
the process of the patient therapy,
the first step is identifying the defective
gene and isolating a normal
counterpart. " To obtain correct gene action, it
may be necessary to put it
into the correct site on the host cell chromosome, or
even to delete the
defective gene", and the DNA can then be replicated each
time the host cell
divided. But if the new cell is injected directly into the
patient’s body, it
will be subject to the body’s immune system that will
recognize it as foreign
and target it to be destroyed along with the healthy DNA
that it is carrying.
So the cells extracted from the patient are to be treated
and adding the new
gene in a test tube in the laboratory to make sure that the
DNA is
inserted in an appropriate place in the genome, and the cells can then
be
returned to the patient’s body. Now it is possible to offer the parents
an
antenatal diagnosis to look over if the fetus is affected by some single
gene
defects. If it does, the parents can choose embryo therapy to cure it
rather
then abortion. While the basic process is similar with the one of
patient
therapy, to do an embryo therapy is a little bit easier than a
patient therapy,
because the immune rejection system of the embryo is not
fully developed. The
new DNA will not be ejected, while the former DNA will
be altered. Gene therapy
seems to be a promising and positive step for the
medical community, but ethical
questions arise every day as we discover more
and more about the contents of the
human genome. Does any person, whether
well or ill, deserve respect as an
individual? If the answer is affirmative,
then carrying out experiments on
patients, as Dr. Martin Cline of the
University of California attempted to do in
1980, is fundamentally
unethical. "The clinicians must examine their own
consciences and decide
whether they behaved correctly and with full knowledge of
the proposed
treatment." "Society has decided that part of it is that a
termination of
pregnancy before approximately 3 months is allowable if the child
would
suffer a serious handicap", but how to define ‘a serious handicap’.
Is it
ethical to terminate the pregnancy, if there is still a chance for the
embryo
to be normal? As the treatment of an early embryo will alter its
inheritance,
"whether gene therapy poses long-term genetic problems to human
inheritance"?
These are questions that will have to be answered by both the
medical
community and the patients, and there are no clear precedents at this
time.
Gene therapy has a promising potential to improve the lives of those who
have
diseases that have until now been death sentenced, but to take it into
real
practice human beings still have a long way to go.