Preimplantation Genetic Diagnosis

Rebecca E. Kopp

ã copyright 1996

In the United States, an estimated 2.3 million couples are considered infertile [Wekesser, 1996]. This creates a large need for infertility specialists and clinics specializing in fertility treatments. With the quickly advancing field of rep roductive services and the quest for creating better, healthier babies, a new service called Preimplantation Genetic Diagnosis (PGD) is being offered in conjunction with In vitro fertilization.

PGD is a procedure that combines In vitro fertilization and genetic screening. In vitro fertilization is a procedure that requires a large time commitment; the entire procedure lasts about four weeks. The woman receives daily injections f or seven to twelve days to stimulate the release of her eggs. After she begins to ovulate, the eggs are retrieved by inserting a needle through her vaginal wall. The eggs are then fertilized in a petri dish. After fertilization, the resulting embryos are allowed to mature to the six or eight cell stage. Then with the use of micromanipulation, a technician extracts one cell from each embryo. Polymerase Chain Reaction is then used to produce multiple copies of the cell’s DNA. [Wekesser,1996] Scientists are then able to test for specific disorders once they know the location of the gene that causes the disorder and have developed a test for its presence [Jaroff,1996]. The healthy embryos are implanted or frozen for future use, and the unhealthy embryos are d iscarded [Kenen,1994]. This procedure is still being perfected and clinics that perform this procedure are scarce. According to Denise Grady [1995], in the United States there are only seven clinics that perform PGD.


PGD was developed to increase the number of healthy children born to couples who carry genetic disorders. It is used to select female embryos for couples who carry genes for hemophilia and Duchenne Muscular Dystrophy which only affect males, and to select embryos which have blood types compatible to their mother’s. It can also be used to test for Tay-Sachs Disease, Fragile-X Mental Retardation, Cystic Fibrosis, Down Syndrome and Spinal Muscular Atrophy. In the past couples who wanted to have childr en, and were carriers of inherited diseases, worried about the possibility of their children inheriting the disease. Parents will no longer have this worry. In 1989, an English couple became the first to use PGD [Grady,1995]. It was used because they were at risk of passing along a form of severe mental retardation. Because it only affected sons, PGD was used to ensure that the couple had a daughter.

Public Policy Debates

Although PGD is a relatively new procedure, there are several ethical questions surrounding its use. One question is, "Should parents be allowed to choose characteristics for their children that are not related to disorders such as their baby’s eye color, personality, or even the sex of their baby?" [Wekesser,1996]. Until the genes responsible for inherited traits such as the previously mentioned are mapped, this is not an issue. If scientists do not know where the gene is located, they are unable to create a test determining the presence of the gene. However, because we do know how the sex of a child is determined, a specific gender can be screened for. Many believe that this should only be allowed in cases where a particular sex is at risk for a sex-linked genetic disorder. To allow parents to arbitrarily decide that one gender is superior to another is sexism and should not be allowed. Doing so would undermine the intent of PGD.

The quest for "perfect" babies is another concern [Maranto,1996]. Where should the line be drawn? Should PGD be solely used to prevent genetic disorders, or should it be used to screen for certain physical characteristics such as hair color? If people are allowed to select characteristics, then others may ostracize children, who do not have these ideal characteristics determined by society. It could create an intolerance of diversity, and feed prejudices.

Another concern relates to the cost of PGD [Grady,1995]. Who will be able to use PGD? It is a fairly expensive procedure that is not currently covered by health insurance. In vitro fertilization can cost up to $8,000 for each round of implantati ons. According to Gina Maranto [1996], in 1989, the average cost of each In vitro fertilization baby was an incredible $50,000. In addition, the cost of genetic screening must be included. If the use of PGD becomes common by those who can afford it (white, highly educated, affluent men and women according to Maranto, [1996]), a social underclass could develop. People who are unable to afford the procedure would be stigmatized if their children carried a disease that was preventable by the use of PG D. This could lead to a society that condemns parents of children with Down Syndrome who had decided not to use the procedure; rather than viewing birth defects as chance occurrences.

A consequence of PGD is embryo experimentation [Macer,1990]. With excess embryos being produced through In vitro fertilization and therefore PGD, the question of what to do with these embryos is presented. Should scientists be allowed to experim ent with the embryos that will not be implanted? If they can, what guidelines will be set?

The most important regulation is determining a time limit for in vitro growth of human embryos. This is the basis of the debate over embryo experimentation. People disagree about when human life begins. When embryos are viewed as "complete" huma n beings, people feel it is morally wrong to perform experiments on embryos. In Norway and West Germany, all human embryo experimentation is banned. Denmark prohibits the preservation of excess embryos. However, most countries such as the United Kingdom, Spain, and Australia have placed a 14-day limit on experimentation. The 14-day limit has been upheld because the neural tissues begin to differentiate after 12 days. After 14 days, nervous coordination is possible. It is unethical to experiment on embryos if it is likely that they can feel pain. In the United States, limits vary from state to state. It is legally possible for clinics in most states to perform early embryo experimentation as long as the clinic is not federally funded. [Macer,1990]

The benefits of PGD are self-evident. It eases the minds of couples who are carriers of genetic diseases. When they use PGD, they are able to have children who are unaffected by the genetic disease that they carry. Another possible benefit is the reduc tion of late abortions. With the use of PGD, women would be less likely to carry babies who have genetic disorders. Because most genetic disorders are unable to be detected until later in the woman’s pregnancy, this would lead to a reduction of the number of abortions due to genetic defects.

Personal Opinion

At the heart of my belief about the use of PGD is my belief that In vitro fertilization should not be an option. I believe that it is an unnecessary procedure that causes more anxiety than good. In vitro fertilization is a procedure t hat is only successful for 21.2% of the couples who use it [Maranto,1996]. Its low success rate, but high acceptance causes unnecessary stresses for the couples who choose to use it.

The expense of In vitro fertilization outweighs its possible good. Not only is it an unreliable procedure, it is expensive. It ranges from $8,000 to $12,000 [Wekesser,1996]. Because of the tendency to implant more than one embryo at a time, peop le who have children using In vitro fertilization, are more likely to have multiple births. According to Wekesser [1996], in 1992 more than half of the children born as a result of In vitro fertilization was from multiple births. The hospital cost for each child in a pair of twins is approximately $39,000 [Wekesser,1996]. This is ten times the average cost of the medical care for a singleton child.

I also believe that In vitro fertilization is often used for selfish reasons. Many couples choose In vitro fertilization because they desire to have a child who is ‘of their blood’. Maranto [1996] says of couples who choose In vitro fe rtilization, "Unlike people who choose to adopt, they often seem to be fixated on having, in the sense of possessing, a child, rather than on being a parent." I believe that if a couple truly wants to have a child, adoption is a better choice. There a re thousands of children in the world who die every year because of improper nutrition and neglect. If we are so concerned about the health of unborn children, maybe we should also consider the health of the children who are already living in our world. I understand that it can be difficult to give up the dream to have children, but I think it is far better to take care of the children that need parents. I know a family who adopted two little girls from China, it was one of the greatest experiences of the ir life. They love their girls and even though they did not give birth to them, they are their parents.

I believe that In vitro fertilization and PGD could easily be abused and used outside of pure medical purposes. Fertile couples may use the combination to create a child with the traits that they desire. This procedure could lead to a re-definit ion of parenthood. No longer would parents be expected to just love their child, they would also be expected to play an active role in deciding what their child would be like. A societal ideal would develop and anyone who fell outside that ideal would be shunned by mainstream society. Take for example Down Syndrome children. This is one of the genetic disorders that PGD screens for. Children with this disorder are often seen as defective, but I think that we often forget the great joy that they bring to o ther’s lives. Having worked with Down Syndrome individuals, I have seen the enthusiasm that they have for live. Their innocent adulation with everyday experiences is refreshing and a blessing to many people. I do not think that we should use In vitro f ertilization and PGD to eliminate people such as these. Everyone deserves the chance to live and experience all that our world has to offer—good and bad. Life is a beautiful experience


Grady, Denise. Unnatural Selection. Vogue. October 1995.

Holme, Howard. Choose Better Human Genes. Obtained from the WWW: HOLME

Jaroff, Leon. Keys to the Kingdom. Time. Fall 1996. V148. N14.

Kenen, Regina H. Pregnancy in the Genetic Age. The Network News. July-August 1994. V19. N4.

Macer Darryl R.J. Shaping Genes: Ethics, Law and Science of Using New Genetic Technology in Medicine and Agriculture. Obtained from the WWW: MACER

Maranto, Gina. Quest for Perfection: The Drive to Breed Better Human Beings. Simon and Schuster: New York, NY. 1996.

Wekesser, Carol ed. Reproductive Technologies. Greenhaven Press, Inc: San Diego, CA. 1996.

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