45 pages • 1-hour read
The Case Against Perfection: Ethics in the Age of Genetic Engineering
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Index of Terms
Cloning
Content Warning: This section of the guide includes discussion of eugenics and ableism.
Cloning is a process that produces two organisms with identical genes. Organism cloning is complex and typically uses a process called somatic cell nuclear transfer, or SCNT, in which the nucleus of an adult somatic cell is transferred into an egg cell whose nucleus has been removed. Provided the egg cell starts to divide normally and form a zygote, it is then implanted in a uterus and allowed to develop into a fetus. The resulting offspring is a clone of the original, though not an exact duplicate, as the nucleus of the adult somatic cell may have mutations in its DNA. The mitochondrial DNA from the donor egg cell is also unique. Cloning can also be achieved using embryo splitting, resulting in monozygotic (identical) twins. This process is not thought to produce true clones.
Dolly the sheep was the first mammal to be successfully cloned using SCNT in 1996. It took 435 attempts before scientists were able to produce a successful embryo. Since then, many different animals have been successfully cloned, including horses, dogs, cats, and monkeys. Concerns surrounding cloning typically include the fear that it will one day be practiced on humans. Countries like Canada, the US, the UK, and Australia have passed laws banning human cloning, and it is generally agreed in the scientific community that human cloning should not be pursued because it would be unethical.
Genetic Enhancement
Genetic enhancement, or genetic engineering, is the act of changing a living organism through genetic modification. This process can happen naturally, as in the selective breeding of plant crops, or via technological intervention like gene editing. Today, gene therapies that treat diseases like bone cancer have been developed thanks to genetic research. This kind of genetic enhancement cannot be passed down to offspring, because gene therapy only repairs or replaces genes found in non-reproductive cells. Sandel explores hypothetical genetic enhancements in The Case Against Perfection, including athletes altering their genes to be stronger, and people using genetic enhancement to improve their memories. These procedures do not currently exist in the real world, but they may soon be possible and therefore require ethical debate.
Preimplantation Genetic Diagnosis (PGD)
Preimplantation genetic diagnosis, or PGD, allows prospective parents to test embryos created via IVF for genetic anomalies like cystic fibrosis and sickle cell anemia. PGD involves taking one or two cells from the embryo and testing the cell’s DNA for genetic disorders or heritable diseases. This process does not otherwise harm the embryo, and after testing, if the embryo is approved by the parents, it is implanted into the uterine wall to continue developing.
PGD has generated a lot of controversy, primarily over concerns about eugenics. If people can select out embryos that will go on to develop conditions like cystic fibrosis, some argue, what is to stop parents and doctors from looking to further control what kinds of embryos are allowed to develop? Who gets to decide which embryos have “undesirable” traits, and what is to stop the process from straying outside the bounds of preventative medicine?
Stem Cell
A stem cell is an undifferentiated cell found in the blastocyst of a developing embryo. They go on to develop into the over 200 kinds of cells found in the human body. Stem cells are also present in the human body in the form of somatic stem cells. Somatic stem cells repair and maintain their surrounding tissue and can be found in bone marrow, fat cells, and blood. Somatic stem cells can be harvested and used in a number of medical therapies to treat diseases like leukemia, lymphoma, and some immune deficiencies. Current research is also looking into stem cell treatments for heart disease, diabetes, and certain neurodegenerative diseases.
Some people object to the use of stem cells extracted from blastocysts in medical research because they believe the blastocyst to be equivalent to a baby. Although stem cells have the potential to become any kind of cell, and a blastocyst has the potential to become an embryo and eventually a fetus, neither a stem cell nor a blastocyst is a form of viable life.
Zygote
A zygote is the earliest stage of embryonic development. The zygote contains two sets of DNA: 23 chromosomes from the egg cell, and 23 chromosomes from the sperm cell, for a total of 46 chromosomes. Following fertilization, the zygote will undergo a two-stage process of mitosis, where the cell divides and multiplies rapidly. After about five to six days, the zygote becomes a mass of about 200 to 300 cells, called a blastocyst. During IVF, the blastocyst is implanted into the uterine wall. Eventually, the blastocyst will become an embryo, after about 10 to 12 days. Finally, nine weeks after the blastocyst is implanted in the uterine wall, the embryo becomes a fetus.
It is important to note the difference between a zygote and a fetus. A zygote has no distinctly human characteristics or qualities. It is a single-celled organism that contains the DNA necessary to produce a new life, but it is not yet a new life. The zygote stage only lasts about four days after fertilization occurs, a point at which it is too early to even detect a pregnancy.
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