IVF and the biopsy of polar bodies from oocytes, blastomeres from cleavage-stage embryos, or trophectoderm cells from blastocysts followed by single cell diagnosis has enabled us to help couples who are at risk of transmitting inherited diseases to their children and to improve pregnancy rates for certain groups of IVF patients. These procedures are used in a technique called preimplantation genetic diagnosis (PGD) (1). PGD was developed in 1990 to offer an alternative treatment for couples at risk of transmitting an inherited disease to their offspring. The main option for such couples is to become pregnant naturally and undergo prenatal diagnosis between 12 and 16 weeks of pregnancy (either by chorionic villus sampling or amniocentesis). The main drawback of prenatal diagnosis is that if the fetus is affected by the disease, the couple have to decide whether to continue the pregnancy or terminate the pregnancy. This is obviously not an ideal option for any couple trying to have a healthy family. With PGD, the couples go through IVF so that embryos are generated in vitro, and one or two cells are removed and used for the genetic diagnosis. Only unaffected embryos are transferred, so that the pregnancy is started with an unaffected fetus. The embryo biopsy is relatively easy to perform for an experienced embryologist. However, the single cell diagnosis is a highly specialized technique and is technically challenging, even for experienced molecular or cytogenetic biologists.
The patients that opt for PGD may be fertile. They are known to be at risk of a particular genetic disorder, either due to already having an affected child or because other family members are affected. In the case of patients carrying chromosome abnormalities, these couples often experience repeated miscarriages due to unbalanced chromosomes in the embryo and fetus, which most often are lethal. Couples may have already undergone prenatal diagnosis and repeated termination of pregnancies. They may have moral or religious objections to termination, or they may be infertile and also be carrying a genetic disease (which may or may not cause their infertility), so PGD is a sensible step to add to their fertility treatment (2, 3).
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Although nobody gets a parenting manual or bible in the delivery room, it is our duty as parents to try to make our kids as well rounded, happy and confident as possible. It is a lot easier to bring up great kids than it is to try and fix problems caused by bad parenting, when our kids have become adults. Our children are all individuals - they are not our property but people in their own right.