Initial counseling
The PGD process begins with a two-part counseling day. The purpose of the counseling is to give the couple all the information, including a thorough explanation about the PGD process, and help them reach the decision if to proceed with the process.
At the beginning of the day, the couple is received by the unit coordinator. They fill out a personal information questionnaire. Because this is a shared process, it is vital that both partners come to the counseling together.
First, the couple meets with Prof. Geona Altarsco and Ms. Orit Freireich for genetic consultation. At this meeting the couple is asked for information about their family and a family tree is built to identify additional genetic factors that might affect the offspring and can be prevented with the help of PGD. Therefore during the consultation the couple might be asked to undergo further genetic testing. Please bring to the consultation meeting all documents relating to the genetic diagnosis of the disease in the family, including genetic screening results and medical information about familial diseases.
Following the genetic consultation, the couple receives information about the IVF process from gynecologists with expertise in fertility, headed by Prof. Talya Geva Eldar, head of IVF in the PGD unit. At this meeting the couple will receive detailed explanations about the IVF process and will be referred to further examinations. You may bring results of previously performed medical tests (such as hormonal profile, documentation of previous IVF cycles and the likes).
Usually at the end of the day the couple will be asked to give a blood sample to help establish a genetic system that will help in the fetal diagnosis.
In-Vitro Fertilization (IVF)
The PGD process mandates an IVF process. The genetic diagnosis is performed on a single cell or a small number of cells taken from a 3-5 day-old fetus created in-vitro. This way only the genetically healthy babies are returned to the uterus.
The woman will receive medical and hormonal treatment for several weeks in order to stimulate her ovaries to create more than one egg cell per cycle. The eggs are then extracted under general anesthesia and fertilized in the lab with the partner's sperm using micro-manipulation.
Biopsy
There are three forms of biopsy:
- Polar bodies of the egg cell. This biopsy is performed on when the mother is the carrier of the genetic disorder. The polar bodies are byproducts of the mitosis and do not contribute to the fertilization process or to the developing fetus. This biopsy cancels the need to perform a biopsy on the fetus itself. However, the results give indication only of the mother's genetic contribution.
- One cell (blastomere) taken from a 3 day-old fetus (when the fetus is 6-8 cells in size).
- A small number of cells (blastocyst) taken from a 5 day-old fetus (when the fetus is approx. 50 cells in size).
The PGD unit at Shaare Zedek Medical Center is the only unit in the country to offer all three possible biopsies. The biopsy is specifically matched to the couple based on their genetic information and their level of fertility in order to achieve the utmost accuracy and success.
Results of the genetic analysis
The result turnaround time is dependant on the type of biopsy performed (between 3 days to 3 weeks), depending on the type of biopsy performed. The test has a 99% accuracy.
Important: This diagnosis does not replace the routine prenatal exams.
In addition, the Israeli and the international Society of Medical Genetics as well as the Israeli Ministry of Health recommend that the PGD result be confirmed by a prenatal examination such as amniocentesis or chorionic villus sampling.
Limitations
The process is meant to reduce the chances of conceiving a child with a familial genetic illness. Therefore only couples with a clear genetic diagnosis that indicates the presence of a genetic disease and that the genetic mutation was located in their family can undergo PGD. The PGD process cannot screen for the presence of other genetic mutations or for unknown defects.
It is also important to keep in mind that in every pregnancy there is a 2%-3% chance of birth defects. IVF with micro-manipulation raises these odds by a small percentage (0.5%-1%). All research done so far indicate that PGD does not increase the chances of birth defects beyond the 3.5%-4% that come with micro-manipulation. This is why regular prenatal care is required even after a pregnancy was achieved by PGD.