Preimplantation genetic diagnosis (PGD) is a reproductive technique applied during the IVF cycle to diagnose possibilities of any genetic disease in the early embryos before implantation and pregnancy. This technology is also used in the field of assisted reproduction in the diagnosis of the presence of any imbalanced inheritance of chromosome abnormalities (translocations or inversions) and for aneuploidy screening.
PGD has benefitted many couples. It is helpful in the following cases:
- Women over the age of 35
- Women with past experiences of one or several miscarriages
- Previous pregnancy with a chromosome abnormality
- Experiences of several failed IVF cycles
- Difficulty in conceiving due to a low sperm count
- When any of the partners carries a balanced structural chromosome rearrangement
- When any of the partners have been affected with an autosomal dominant genetic disease, like Marfan syndrome
- Family history of Huntington disease in any of the partner
- When any of the partners carries a recessive genetic disease, like cystic fibrosis
- When any of the partners carries an X-linked genetic disease like hemophilia or Duchenne Muscular Dystrophy (DMD)
- When couples wish to balance the gender in the family
How is the PGD performed?
Preimplantation genetic diagnosis is initiated with the basic procedure of In Vitro Fertilization (IVF). This includes retrieval and fertilization of eggs in a laboratory. The embryo divides itself into multiple cells over a period of three to five days.
Genetic conditions tested during PGD
PGD is also used to virtually diagnose the genetic condition of a specific gene and the cause of that condition. In Ukraine, it is currently approved to screen embryos for more than 250 genetic conditions.
The process of PGD is usually as mentioned below:
It involves the normal In Vitro Fertilization (IVF) treatment in order to collect and fertilize the eggs.
Within a span of 2 to 3 days, the embryo forms in the laboratory and divides the cells by itself. Each embryo consists of 4 to 12 cells.
A professional embryologist takes out one or two of the cells, known as blastomeres, from the embryo.
The cells collected from the embryo are tested to detect the genetic conditions that might affect the health or features of the baby. Every single embryo is examined and the removed number of cells are observed to find out the healthiest embryo of them all.
The embryo, which is found to be unaffected by any of the negative genetic conditions, is introduced into the womb after 4 to 5 days of egg retrieval, and thus, the pregnancy is developed.
The remaining unaffected embryos are mostly cryopreserved for later use. The embryos which are found to be affected by certain conditions are either allowed to perish or used for research works.
Risks Associated with PGD in the Surrogate Process
The procedure of embryo biopsy consists of a little risk, as it may accidentally damage the embryo during the biopsy. Almost 1% of the embryos are damaged during the process of taking out the cells from them. This percentage is, however, debatable and some embryologist consider it to be less than 1%.
Nonetheless, PGD being a relatively new technology appears to have limited risks and can be weighed successfully against the benefits that it brings for each couple.
Benefits of PGD
Here are the benefits that are gained from PGD:
- PGD can detect more than 100 varieties of genetic conditions that might affect the pregnancy, delivery and the child in future. Hence, the child born out of such embryos tested through PGD are free from almost all the genetic disorders.
- The examination is executed before embryo implantation and, thus, it allows the couples to decide whether they actually want to continue with the pregnancy. In case the couple decides to discontinue with the embryo, those could be sent for research purpose that is a long term benefit for the entire subject of IVF and surrogacy.
- This biopsy procedure enables couples to go for biologically fit children, which otherwise might not have been possible. Couples, who are putting all their energies into bringing a child of their own genes home, should always want their child to be genetically fit.
Concerns of PGD
The concerns associated with the use of PGD are:
- PGD, of course, reduces the chances of pregnancy with any genetic disorder, but cannot entirely eliminate this risk. In specific cases, further examination is required to ascertain whether any genetic factor is still present in the pregnancy.
- PGD does not detect certain syndromes that might crop up as the child reaches middle age.
- Pre-implantation genetic diagnosis cannot be replaced with prenatal testing.
PGD Increasingly used with In Vitro Fertilization
Preimplantation genetic diagnosis (PGD) is increasingly being used at various Fertility Centers to improve the success rates of IVF pregnancy in those couples who had prior IVF failures with unexplained reasons. As per a recent estimation, almost half of the pregnancy failures in IVF have been remained unexplained due to the issues related to the quality of the embryo. The statistics are quite depressing for many couples who have experienced multiple pregnancy failures in IVF. This not only leads to physical and mental drainage of the couple but also monetarily affects them a lot. We have been closely examining the quality of embryo before transferring them into the surrogate’s womb. PGD is entirely legal in the nation, and, hence, couples visiting Ukraine for their IVF and surrogacy program can make the most out of it. The success rate of such embryos those are planted after PGD is more than 70%.
Myths related to Preimplantation Genetic Diagnosis (PGD)
PGD has been used by couples who wish to plan their family and maintain gender balance. Couples who already have a son can go for daughters next time and can get it tested through PGD. During the phase of 24 chromosome screening, the embryologist can find out the gender of the child that is going to form after the embryo transfer. However, no one can ever plan the gender of the child-to-be by PGD. In many cases, couples have been found to demand babies of their own gender choice through PGD, which is absolutely a wrong concept. In many cases, couples choose to not continue with a particular embryo due to the gender it has been detected out. In such cases, they donate the embryo for future use for any other couple. Embryologists store those embryos in frozen form and help other childless couples to form families through them. Remember, the embryos that have been discarded only due to a particular gender choice are all high quality in nature. Those were only discarded as the couple wished to have babies of their own gender choice. Those embryos can be very well used in later surrogacies and be immensely fruitful for someone else.
So, it should be understood that PGD can only help to detect the gender of the child-to-be, and is not a process to plan its gender. This should be clear to every intended couple going for PGD procedure.