Sunday, November 2, 2008

PGD (pre genetic diagnosis)

Pre Genetic Diagnose (PGD) is a little controversial and has not been shown to be accurate. Studies have shown that PGD is not very accurate and test results are not conclusive. Eggs that are normal, may show as abnormal in testing and be discarded, while abnormal eggs show as normal and be implanted back into the mother.

PDG is basically used to find out if a fertilized egg has an indication of having a genetic disorder.

"General guidelines for who should be offered PGD in most clinics are:
  • Couples with family histories of inherited genetic diseases
  • Couples where either partner is a carrier of chromosomal translocations (their chromosomes in their genes are “mixed up” – part of one chromosome has broken off and joined with another)
  • Women who have experienced recurrent miscarriages
  • Women over the age of 38 (which is considered an advanced female age for bearing children) attempting IVF
  • Any couple who has experienced repeated failed attempts at IVF (usually 3 or more)
  • Any couple where a man’s sperm count is low that it is necessary to perform ICSI
A single cell is extracted from an egg that has divided cells of 8 or more. The cell is then tested for genetic diseases. For women who are 38 or over this test can indicate which eggs are more likely to result in a successful pregnancy.

"This means that it is not necessarily better to use PGD just because you have had previous IVF cycles that did not work or because you are a woman over 38. PGD for this reason has not been proven to increase chances of pregnancy. However, if you know you have a chromosomal translocation or you are carrying a gene for a genetic disease or disorder, and your potential child is at a high risk of inheriting medical problems, PGD is useful for increasing the chances of a live birth and a healthy baby." Womens Health Information

Unfortunately the test is not always reliable.

"By relying on the result of one cell from the multi-cell embryo, it assumed 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." Wikipedia

"However, PGD (referred to as PGS in Europe) for routine aneuploidy screening during IVF for infertile couples has recently come under severe criticism in Europe owing to several prospective, randomized control studies in Holland and Belgium. PGS has failed to show any improvement in IVF clinical outcome per initiated cycle for advanced maternal age, nor for recurrent implantation failure." Infertility.com

"PGD is very controversial because of the many ethical issues involved with this procedure. Many feel that it is unethical to create an embryo outside of the body and then destroy it. This is especially so because PGD is not 100% accurate, which could lead to the destruction of a normal embryo. Also, PGD does not guarantee that a child will be born without a disease or disorder since genes are not the only things that cause medical problems – fetal environment has a large impact as well. " Women's Health UK

Hopefully this will give you some information to make a difficult decision. Good Luck!


Sources:
Wikipedia
Infertal.com
Womens Health UK

No comments: