Genetic screening or PGS is a more advanced treatment offered to one a couple with infertility. It is normally combined with IVF, and involves biopsy and genetic testing of the embryos before they are transferred.PGS is a technique which ensures that the embryo is genetically healthy (Euploid) before it is transferred back to the uterus.
The method of embryo biopsy is the same for both PGS and PGD but the reasons for which they are done are different. PGS is the test prescribed to screen all 23 sets of chromosomes and detect any addition or deletion of chromosomes. For example: Down Syndrome, Turners Syndrome. Whereas, PGD is used to check for a single gene defect. For Example DMD, Thalassemia.
We have noticed that both terms are often misunderstood, so we will do our best to make things clearer.
PGS (Pre-implantation genetic screening)
PGS is a specialized procedure that is used by fertility specialists to determine the number of chromosomes in each embryo created during IVF.
The expected number of chromosomes expected for healthy humans is usually 23 pairs inherited from both parents. PGS enables us to check if the developed embryos have fewer or excess of this number.
In normal IVF, two or three embryos are usually transferred into the uterus for implantation and to increase the chances of pregnancy. Unfortunately, this comes with a risk of multiple pregnancies.
With genetic screening, the embryos can be examined, and only the one with the right amount and order of chromosomes is implanted. This reduces the risk of aneuploidy, miscarriages and multiple pregnancies.
This is important because having too many or too few chromosomes (aneuploidy) is one of the major causes of failed implantation and miscarriages. Unfortunately, the odds of chromosome abnormalities increases as a woman ages, so it’s common to recommend PGS with IVF for women of advanced maternal age. Women who have experienced recurrent miscarriages may also undergo the test.
Although PGS doesn’t test for specific diseases, it can also help to detect disorders such as Turner’s syndrome or Down’s syndrome. This usually occurs when there’s translocation, where a part of a chromosome breaks off and reattaches on another chromosome.
The major advantage of PGS is that it maximizes the chances of conception by reducing the risk of miscarriage. It can also help to prevent multiple IVF cycles, thus saving you time and money. We mostly recommend this screening to women over 35 to increase their chances of a successful healthy pregnancy.
It is important to understand that these advanced techniques are not for everyone and should be recommended only in cases where it is indicated.
Patients without any genetic abnormality can benefit from PGS. Other cases why PGS may be recommended includes:
Couples with an existing genetic disorder can employ PGD to test developed embryos for specific gene mutations. In other words, PGD ensures the couple have a child that doesn’t have the same genetic defect they have.
A genetic defect can also be passed to the child if the couple don’t have it but is inherited from a precedding generation.
This is why beyond testing patients; we also try to evaluate their family history to identify any thing that can potentially affect the unborn child.
After using PGD to identify defective embryos, we separate them from the ones that have no genetic disorder. The latter are the ones that are used for implantation. This helps in greatly reducing the chances of having a child with gene defect.
Couples with a history of genetic abnormalities can ensure the trait is not passed to their unborn child by undergoing PGD. Some of the diseases that can be prevented this way include:
Archish IVF fertility center is one of the most trusted clinics in India for PGS and PGD procedure. Not all couples are required to take both tests but patients with single gene mutations may take both to check for both genetic defects and aneuploidy.
To speak to one of our doctors, book an appointment today.