What Is the Purpose of PGD?
Modern reproductive technologies have gone through a major evolution for the last decades which has given a chance for either single people or those in a partnership to have children. In addition to in-vitro fertilization there are now other techniques that improve the quality and allow us to broaden the knowledge about the biological material. One of such techniques is Preimplantation Genetic Diagnosis (PGD) which was first used in 1989 by the American geneticist called Alan Handyside. His aim was to check the presence of a specific gene which becomes a reason for the occurrence of cystic fibrosis. Modern PGD allows to test much more mutations.
What is Preimplantation Genetic Diagnosis?
Preimplantation Genetic Diagnosis is the genetic screening of embryos that were created by the means of IVF. This test is different from the prenatal screenings as it is done when woman isn’t pregnant yet. The main goal of this procedure is the genetic testing of embryos.
It allows to check if the embryo is healthy on a stage before the actual transfer. The development of PGD has become a great step forward in genetics. It makes possible to avoid transferring unhealthy embryo in the uterus in the first place and to prevent pregnancy terminations after detecting some kind of abnormalities when the woman is already carrying a baby.
The list of genetic diseases that can be detected by means of PGD is quite extensive and includes:
. Fragile X Syndrome;
. Achondroplasia;
. Beta Thalassemia;
. Cystic Fibrosis;
. Huntington Disease;
. Marfan Syndrome;
. Sickle Cell, etc.
In addition, patients receive the information about gender of embryos as some diseases occur only in males or females.
What Is the Purpose of PGD?
PGD has indications as any other medical procedure and should be recommended by a doctor. Before starting the IVF, couple can inquire about the necessity of PGD, however, in most cases, fertility doctors point it out the indications or their absence at the very beginning. The most common reason for performing the test is the significant risk of passing the hereditary diseases to a future baby. If one of the partners is aware of his/her genetic disorders, PGD would become an only way to make sure their baby won’t have it too.
Another widespread purpose of PGD is the advance age of one or both partners. The chance of giving a birth to a healthy baby decreases with age and doctors may suggest re-insuring. Some parents consider it in case they have already given birth to a baby with a chromosomal abnormality or they have had such incidences in their family medical history.
PGD is often helpful for couples with several miscarriages in a medical history or those who had at least 2 unsuccessful IVF cycles. Embryos obtained during these attempts have satisfactory quality, judging from what can be seen with an eye of an embryologist. The reason is often genetic abnormalities in these embryos. Doctors may also offer patients PGD in case of infertility of an unknown nature, male factor, etc.
What Are the PGD Steps During an IVF Cycle?
The first step is the creation of embryos themselves: the medical team and patients are waiting for 5 days to see which embryos would eventually become blastocysts. Only 5-day embryos of a good quality can be tested. Most of the IVF clinics use the Gardner’s classification to evaluate the quality and it consists of three grades that depend on certain factors. Embryos of a poor quality cannot be genetically tested, vitrified or transferred as it would give no result.
The following step is the trophectoderm biopsy during which embryologists separate several cells from the outer layer of an embryo. It will develop into placenta during the pregnancy so no damage to fetus is done. These cells are then sent to a specially equipped laboratory for the actual testing and embryos are vitrified and cryostored in a liquid nitrogen.
Who Should Have PGD Or PGS?
PGD is often used to detect single-gene disorders and when patients know which type of abnormality they are looking for. Nowadays, PGD offer a wide range of abnormalities they are able to detect. PGS, cannot be used to verify the presence of the specific disease. In its turn, this test makes it possible to check the number of chromosomes and is frequently opted due to recurrent miscarriages. An embryo with the wrong number of chromosomes has a little chance to implant and even if it does, there is a high chance of having a baby with genetic disease.
How Are Embryos Chosen for Transfer?
After getting information about embryos from the laboratory, the next step will be the preparation for the embryo transfer and the transfer itself. The medical staff mainly recommends transferring one embryo of the best quality. First, the strongest embryo is used and then all other ones in descending order.
Those embryos which have proven to be unhealthy are destroyed because they cannot be transferred or donated to any other patient. The destruction is only done on condition of a written application from patients by means of thermal shock. Please, note, that the legislation differs from country to country in this regard.
Where Does the PGD Testing Occur?
Cells, which were taken from embryos are sent to laboratory. There are special laboratories with equipment that allows performing genetic screenings on embryos. Not every clinic has its own laboratory to perform PGD and most of the medical institutions cooperate with them to offer their patients PGD. What is important is the duration, patients have to take into consideration that the material is being processed for at least one month, depending on the lab.
Generally, PGD is not an option for every couple and if a couple is young or donor material is used, doctors may not suggest proceeding with PGD due to the low risk of detecting any kind of abnormalities.
Read more about: What Is the Purpose of PGD?
About Iranian Surgery
Iranian surgery is an online medical tourism platform where you can find the best doctors and fertility specialists in Iran. The price of PGD in Iran can vary according to each individual’s case and will be determined by an in-person assessment with the doctor.
For more information about the cost of PGD in Iran and to schedule an appointment in advance, you can contact Iranian Surgery consultants via WhatsApp number 0098 901 929 0946. This service is completely free.
Source:
https://parensfertility.com/blog/what-is-preimplantation-genetic-diagnosis-pgd/