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A SUMMARY OF “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.
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