Preimplantation genetic diagnosis (PGD)

NOTE: In vitro fertilization (IVF) - creating human embryos outside the womb, for evaluation and transfer, or storage - opened a Pandora's box of ethical problems stemming from this process of constructing children. This commentary addresses the subject of PGD, one of the serious ethical problems resulting from the IVF industry.

Preimplantation genetic diagnosis (PGD) was developed in Britain in the mid-eighties as a way to test human embryos (created through IVF) for genetic abnormalities prior to transferring them to the mother. PGD was viewed as an alternative to prenatal testing (where the fetus is tested in-utero). In 1990, the first child was born after PGD testing.

PGD involves the removal of one or two cells from an early-stage in vitro embryo, usually at the eight-cell stage. The extracted cells are then analyzed to determine if the embryo possesses certain genetic traits. PGD was initially used to identify monogenic and sex-linked disorders (i.e., diseases or conditions that could be linked to a single gene, such as Cystic Fibrosis, Tay Sachs disease and sickle cell anemia; or disorders linked to the x-chromosome).

Developments in the technology now allow PGD (also sometimes called PGS, for preimplantation genetic screening) to test or screen for a broad range of genetic abnormalities, including aneuploidy (where there is the wrong number of chromosomes, possibly leading to conditions such as Down Syndrome, Trisomy, or Turner Syndrome), as well as genetic mutations that may signal adult-onset diseases such as Huntington Disease or Alzheimer disease. PGD can also be used to analyze human leukocyte antigen (HLA) tissue, in order to discover if an embryo's HLA matches that of an existing, sick sibling. If the HLA matches, the transferred embryo could provide lifesaving tissue for his or her older sibling after birth.

Finally, PGD can now be used, and has, as a way to screen for certain conditions, such as deafness or dwarfism, by parents who desire children with the same conditions that they themselves have.

PGD lucidly manifests the instrumentalization and commodification of life inherent in IVF. Over and above the concerns that PGD poses a potentially significant harm to an embryo which has already been brought into being outside of a loving conjugal union (a recent study found that PGD reduced the birth rate for embryos that were tested), it further intensifies our culture's eugenic willingness to screen out certain "unfit" humans. We are now making new human beings "ready to order," as people use PGD to choose embryos purely on the basis of sex, to create and select embryos to serve as "spare parts" tissue donors for an older sibling, or to create children intentionally with a certain "disability" such as deafness or dwarfism.

In the United States , there is no federal regulation directly addressing PGD. A 2005 study conducted by the Center for Genetics and Public Policy at Johns Hopkins University found that 74% of the IVF centers surveyed offer PGD, providing approximately 3000 cycles with PGD in 2005. Out of the respondent clinics, almost 9% (320 cycles) of all PGD was done for non-medical sex selection, and 43 cycles were reported for HLA tissue matching.

Chris Oleson Ph.D . is associate professor of philosophy for the Legion of Christ at their Center for Higher Studies in Thornwood, New York. He teaches the history of modern philosophy, the philosophy of culture, as well as various courses in moral and political philosophy. He received his Ph.D. in philosophy from the Catholic University of America and a Master of Arts in Religion from Yale Divinity School.

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