Case studies will also appear throughout the on-line course. They are designed to challenge the reader to consider the implications of stem cell science, medicine and bioethical conundrums from diverse perspectives.

Case Study #1 Background: Pre-implantation genetic diagnosis (PGD)

Soon after fertilization, the haploid nuclei of egg and sperm merge to form a single nucleus with the diploid number of chromosomes. This one-cell zygote divides as it moves along in the fallopian tube; divisions keep occurring. Up until the 8-cell stage, each cell is totipotent, having the ability to form the placenta as a defining feature.

The 8-cell stage of the embryo is a landmark as this is when pre-implantation genetic diagnosis (PGD) can take place. This PGD procedure is a remarkable melding of genetics with embryology where bioethical oversight has a role.

Those who have provided their ova and sperm to create an embryo may have specific concerns related to heritable diseases due to their family’s medical history. PGD has become an increasingly used technology to prevent embryos carrying specific genetic mutations from being implanted into the woman’s uterus.

Taking advantage of the IVF process, many eggs are harvested, fertilized, and allowed to develop to the 8-cell stage. At this point, using a technique developed by Dr. Mark Hughes, one cell of the 8-cell embryo is gently suctioned out of the bolus of cells.


Pre-implanted embryos found to have genes for genetic disorders such as Huntington’s disease, cystic fibrosis, Down's syndrome, muscular dystrophy, Tay Sachs disease, and many others are likely to be discarded. One or two of the embryos that are free of screened genetic mutations will be implanted into the uterus to gestate. The remaining pre-implanted embryos that are free of the mutation may be stored for future use in the fertility clinic (Damewood 2001; Verlinsky, Rechitsky et al. 2001).

Ethical Issues
Needless to say, while PGD is a much welcomed advance, significant issues are generated. Many in the disability community are concerned that embryos are screened out that could develop into productive and much loved individuals.

Individuals could argue that parents and doctors choosing to not implant embryos with certain grave genetic conditions may in fact ultimately be preventing the creation of a hypothetical individual who might have a very difficult if not prematurely terminated life. Furthermore, there are financial and emotional costs to society that should be considered. These are very sensitive and emotional issues, yet implicit in many parents' thinking about embryo termination is preventing suffering, lifelong struggle, and cost. Society is increasingly concerned about how to pay for all manner of costly interventions and schooling.

Additionally, PGD paves the way to create “designer” babies, promotes gender selection, and creates opportunities to produce a child with particular genetic features that will be used to cure or treat relative.
The discarded embryos found to contain particular mutations, for example, can serve as valuable in vitro models by researchers who are studying the source of genetic disorders and how the genes affect development.

Thought Question

Is it ethical to use the pre-implanted embryo containing the genetic mutation for cystic fibrosis to generate stem cell lines able to be used to study the disease in vitro?

Case Study #2: Embryo selection to provide stem cells for an ill sibling

Mr. and Mrs. Doe are both carriers for the recessive disorder Fanconi Anemia. Mrs. Doe gave birth to their first child, Molly, who has this serious disorder that includes fused joints, missing thumbs, and an incomplete gut. The long-term prognosis is grim as those with this disorder develop leukemias and cancers and have a shortened life expectancy. Given this, the Does were desperate to identify a donor who could provide a matching hematopoietic stem cell (HSC) transplant that would be an HLA match to Molly’s tissue. Not able to locate such a match, they ultimately resorted to utilizing pre-implantation genetic diagnosis (PGD) technology. Here, an embryo, among several that were created using IVF technology, that was a genetic match to Molly and was free of the gene causing Fanconi Anemia, was implanted into Mrs. Doe’s uterus. Mrs. Doe subsequently gave birth to Adam, whose umbilical cord blood stem-cells were removed and used for a stem cell transplant to cure Molly of the disorder.

(Case adapted from: What are the medical and ethical considerations of this actual case*? (Sankoorikal 2001; Verlinsky, Rechitsky et al. 2001)

Thought Questions

What are the ethical implications of conceiving a child for the sole purpose of treating another sibling?
Is Adam being exploited?
Is Adam just a means to an end?
If more stem cells are needed for Molly when Adam is 14 years old, can he refuse to undergo a bone marrow procedure to that would provide stem cells for his sister?

Previous || Next