Biomedical Engineering Reference
In-Depth Information
bicide, into soybean plants so farmers can spray to kill weeds without
harming the bean plants. in humans, it can mean inserting a normal gene
for an important enzyme into the DnA of white blood cells to restore
normal function to a patient's immune system. in the future, it might mean
inserting genes into eggs or early embryos to increase the cognitive abili-
ties of upcoming generations.
This chapter is about genetically engineering human cells. in it we con-
sider some examples of human cell genetic engineering already performed,
some successful and some tragically unsuccessful. Then we look at the
prospects for human genetic engineering in the future. finally, we explore
moral issues that come with various types of human genetic engineering.
What Are the Types of Genetic Engineering?
All human genetic engineering involves manipulating DnA in living, hu-
man cells. Depending upon the kind of cell being altered and the motive for
doing so, there are four types of human genetic engineering. since human
motives are often difficult to define, the boundaries between some types
of genetic engineering are also elusive. nevertheless, categorizing genetic
engineering into four types helps us to think about the various ethical is-
sues arising from the technology.
one way to classify genetic engineering is by the cell type being engi-
neered:
somatic
(body)
cells
versus
germ cells
(eggs and sperm). somatic cell
genetic alterations last only for the lifetime of the person receiving the ge-
netically engineered cells; the alterations are not passed on to future gen-
erations. By contrast, germ-line genetic alterations are potentially immor-
tal since they can be passed on to future generations.
A second classification of genetic engineering is based on motive: thera-
peutic versus enhancing. Gene therapy aims to cure a genetic disease or
treat some other genetically based health problem. Genetic enhancement,
not yet performed in humans, would aspire for cosmetic changes in non-
health-related traits. for example, increasing the stature of or diminish-
ing the fat deposits in a normal person would be enhancements.
in their 1997 topic,
Ethics of Human Gene Therapy,
bioethicist leroy Wal-
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