Preimplantation Genetic Diagnosis - Ethical Issues

Ethical Issues

PGD has raised ethical issues, although this approach could reduce reliance on fetal deselection during pregnancy. The technique can be used to determine the sex of the embryo, and thus can be used to select embryos of one sex in preference of the other in the context of "family balancing". It may be possible to make other "social selection" choices in the future that introduce socio-economic concerns. PGD allows discrimination against those with disabilities. Only unaffected embryos are implanted in a woman’s uterus; those that are affected are either discarded or donated to science.

PGD has the potential to screen for genetic issues unrelated to medical necessity, such as intelligence and beauty, and against negative traits such as disabilities. The medical community has regarded this as a counterintuitive and controversial suggestion. The prospect of a "designer baby" is closely related to the PGD technique, creating a fear that increasing frequency of genetic screening will move toward a modern eugenics movement.

Three percent of PGD cases in the US in 2006 were used to select an embryo for the presence of a disability. Couples involved were accused of purposely harming a child. This practice is notable in dwarfism, where parents intentionally create a child who is a dwarf. Another ethical concern is selecting a child to provide a cure for an already existing affected child by using PGD and HLA typing so that the umbilical cord blood or bone marrow from their second child can be used as a curative treatment.

By relying on the result of one cell from the multi-cell embryo, PGD operates under the assumption that this cell is representative of the remainder of the embryo. This may not be the case as the incidence of mosaicism is often relatively high. On occasion, PGD may result in a false negative result leading to the acceptance of an abnormal embryo, or in a false positive result leading to the deselection of a normal embryo.

Another problematic case is the cases of desired non-disclosure of PGD results for some genetic disorders that may not yet be apparent in a parent, such as Huntington disease. It is applied when patients do not wish to know their carrier status but want to ensure that they have offspring free of the disease. This procedure can place practitioners in questionable ethical situations, e.g. when no healthy, unaffected embryos are available for transfer and a mock transfer has to be carried out so that the patient does not suspect that he/she is a carrier. The ESHRE ethics task force currently recommends using exclusion testing instead. Exclusion testing is based on a linkage analysis with polymorphic markers, in which the parental and grandparental origin of the chromosomes can be established. This way, only embryos are replaced that do not contain the chromosome derived from the affected grandparent, avoiding the need to detect the mutation itself.