Typically:
- One or both partners have been genetically screened previously, and found to be a carrier, or
- One or both partners are from a human population known to have a high incidence of a genetically-based disease or disorder.
If an embryo is found to be genetically defective, it is normally destroyed. This produces a very serious concern for many pro-life supporters who believe that every pre-embryo, embryo and fetus is a human person. Destruction of a pre-embryo is considered a form of murder.
Pre-implantation genetic diagnosis (PGD) is recommended when couples are at risk of transmitting a known genetic abnormality to their children. Only healthy and normal embryos are transferred into the mother's uterus, thus diminishing the risk of inheriting a genetic abnormality and decreasing the risk for adverse outcomes such as early and late miscarriage and late pregnancy termination (after positive prenatal diagnosis).
The Technique that can be used to determine a baby's sex is pre-implantation genetic diagnosis (PGD). This procedure is regulated by the HFEA and carried out by licensed clinics, but is used for medical purposes only. First, embryos are created using in vitro fertilisation (IVF). The genes of these embryos are then analysed and only those of the desired sex are re-implanted in the woman's uterus. PGD is usually only used when parents are at risk of having a baby with a serious genetic condition that only affects one sex.
Primary candidates for PGD include the following:
- Couples with a family history of X-linked disorders (Couples with a family history of X-linked disease have a 25% risk of having an affected embryo [half of male embryos].)
- Couples with chromosome translocations, which can cause implantation failure, recurrent pregnancy loss, or mental or physical problems in offspring
- Carriers of autosomal recessive diseases (For carriers of autosomal recessive diseases, the risk an embryo may be affected is 25%.)
- Carriers of autosomal dominant diseases (For carriers of autosomal dominant disease, the risk an embryo may be affected is 50%.)
It's not science fiction. Nowadays prospective parents can not only know the sex of their unborn child but also learn whether it can supply tissue-matched bone marrow to a dying sibling and whether it is predisposed to develop breast cancer or Huntington's disease -- all before the embryo gets implanted into the mother's womb.
"What I think the public doesn't understand is that this technology is not in the distant future," said Stanford law Professor Hank Greely, kicking off a Feb. 27 conference that explored the controversial topic at the crossroads of human genetics and reproduction: pre-implantation genetic diagnosis (PGD). Presented by the Stanford Center for Law and the Biosciences, a new program directed by Greely, the conference drew more than 100 people to hear a panel of eight nationally known law professors, bioethicists and biomedical research scientists discuss whether California should regulate PGD.
