Pre-Implantation Genetic Diagnosis (PGD)

“We just want our baby to be healthy …” That wish is expressed by all prospective parents, yet is especially touching in couples who are at high risk for passing on a severe genetic disorder that they are known to carry. Traditionally, such couples were offered prenatal diagnosis by amniocentesis, but with a substantial likelihood of facing the dilemma of a mid-trimester pregnancy termination.

We are now able to offer pre-implantation diagnosis during an IVF cycle in order to select unaffected embryos for transfer in individuals who carry the genetic markers for certain inherited disorders. We’re delighted to report that our first two PGD pregnancies have now delivered healthy babies unaffected by the genetic disorder carried by one of their parents.

The first couple was featured in an article in The Province on June 5, 2006. Ironically, the 28 year old husband/father is a PhD student working at BC’s Centre for Molecular Medicine and Therapeutics where he’s focusing his research career on trying to find a cure for Huntington disease – the very disease that he himself carries and that has affected his mother and grandmother.

The goal of PGD: to establish a pregnancy that does not have the severe genetic disease which the couple is at high risk of transmitting.

Eligible individuals must carry an identifiable genetic marker for a serious inherited disorder, such as Huntington disease, Fragile X, thalassemia, cystic fibrosis, Marfan’s Syndrome, a balanced translocation, etc.

The process: Single cells are biopsied from three-day old embryos & transported overnight to a specialized molecular genetics lab in the USA. Screening occurs the following day for the specific genetic marker using polymerase chain reaction (PCR) or fluorescent in situ hybridization (FISH) or From the embryos that continue to develop, unaffected blastocysts are selected for transfer on day five.

The caveats: PGD is a complex and expensive process that requires couples to undergo an IVF/ICSI cycle which they may not otherwise need. The process is generally only suitable for couples who find standard prenatal testing and mid-trimester pregnancy termination unacceptable. There is also a small risk that there will be no surviving, unaffected embryos for transfer. Eligible couples must have a known genetic disorder for which they’ve had genetic counseling:

• We cannot screen embryos at random for unspecified abnormalities
• Canadian law prohibits PGD for gender selection for social reasons

For further information: Feel free to contact us for more information on PGD. Alternately, your physician may wish to contact the Provincial Medical Genetics Program at 604-875-2157 for assistance with investigation and counseling related to specific genetic conditions.

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