Development of assisted reproduction technology (ART) and therefore availability of embryos in in vitro conditions has made genetic diagnosis of the embryos prior to implantation possible, enabling couples to avoid termination of pregnancy after routine prenatal diagnosis. Now, preimplantation genetic diagnosis (PGD) can improve IVF efficiency by preselection of euploid embryos for transfer, and has become an integral part of assisted reproduction.
The idea of preimplantation genetic diagnosis goes back to 1967 when Edwards and Gardner succeeded in sexing rabbit embryos at the blastocyst stage. The medical society waited until 1989 to use similar technology in humans for the avoidance of genetic diseases. In 1989, Hanyside and his colleagues implemented PGD for sex determination of embryos because of an X-linked disease. The indications for performing this technique soon widened and gradually more ART centers offered this service to their patients. to date, over 10000 PGD cycles have been performed worldwide with more than 1500 healthy births. The PGD technique has a great value for those countries, which according to their religious and ideological laws have banned abortion.
Another issue with PGD is cost. Over the years the cost has been dropping, but it is still expensive technology.
Your doctor may discuss PGD with you if:
It is difficult to assess success rates for PGD because there is currently little data available. Most women use this treatment not because they have fertility problems but because they want to avoid having a child with a genetic disease.
As with most fertility treatments, success depends on many factors, including the woman’s age and whether a cause of infertility has been identified.
Sometimes no embryos are suitable for transfer to the womb, for reasons including:
PGD can be used to test for almost any genetic condition where a specific gene is known to cause that condition. At the moment nearly 400 conditions have been approved for testing.
The PGD treatment itself is thought to be very safe – there is no evidence that babies born following PGD suffer from any more health or developmental problems than babies born using IVF alone. There are risks from having IVF though, some of which can be very serious.
Although an embryo can develop normally even when it has had a cell removed, there is a possibility that some embryos may be damaged by the process, which means they would need to be discarded. In addition, PGD is not 100% accurate so there’s a small chance the tests may not work or may give the wrong information.
The process is secured and 99% to 100% guarantee is given to select the desired sex of the embryos for pregnancy. Since the embryos are selected before pregnancy, this reduces the chance of termination of pregnancy or abortion if desired sex is not achieved. The embryos are tests to detect the genetic disorder, which means only the healthy embryos get the chance to get into the womb. This reduces the chance of miscarriage. In the process of PGD there are some left-over embryos, which can be stored in a frozen condition in the lab and can be used in case of miscarriage or in the time of next pregnancy.
The cost is the main disadvantage of using this process. It is really very expensive for the common people. The PGD process comes with a high chance of getting twins, because in some cases two embryos can be implanted together inside the womb. Some people view embryos as human life and for them it will be a great issue of how to use the unused embryos? They cannot decide whether they should be donated to some other couples or discarded. This may cause a serious issue for those who consider the embryos as human lives.
PGD and PGS require in vitro fertilization (IVF), which involves risks of ovarian hyperstimulation syndrome, multiple pregnancy, and increased risk of birth defects not related to the genetic test.
Unfortunately, sometimes there are no embryos suitable for transfer to the womb. This could be because: