What is Preimplantation Genetic Screening test?

PGT (Preimplantation genetic Testing) is a genetic screening test that is performed on embryos (after IVF / ICSI) before embryo transfer.

The most common reason for pregnancy failure (implantation) is genetically abnormal embryo, which can only be identified after the PGT thus The ultimate goal of PGT is to identify genetic abnormalities in embryos, which can help in selecting the healthiest embryos for implantation and thereby reducing the risk of any kind of abortions/miscarriage and passing on any genetic disorders to your baby.

Who should opt for PGT?

PGT is a preferred choice and should be performed in most of the cases;

• People age above 35 years due to higher risk of abnormal embryo genetics with normal reproductive aging.
• Couples who are having any family history of genetic disease- can have abnormal reproductive biology.
• People with a history of recurrent miscarriages due to chromosomal abnormalities.

What kind of genetic disease can be treated with PGT?

Akruti IVF Centre provides the most advanced genetic screening or diagnosis of the embryos, Pre-implantation genetic screening (PGS) and Pre-implantation genetic diagnosis (PGD). In scientific terms, the new technical terms are Pre Implantation Genetic Testing for Aneuploidy or structural rearrangements or Monogenic (single-gene) diseases.

1. Pre Implantation Genetic Testing for Aneuploidy (PGT-A)
2. Pre Implantation Genetic Testing for Monogenic diseases (PGT- M)
3. Pre Implantation Genetic Testing for Structural Rearrangements (PGT-SR) :

1. Pre Implantation Genetic Testing for Aneuploidy (PGT-A) –

Embryo abnormality or aneuploidy which is from having abnormal number of chromosomes. 80% of miscarriages or pregnancy losses are due to embryo having abnormal number of chromosomes. In a fertile patient with normal pregnancy chances, about 40% of embryos are abnormal. In a patient with recurrent pregnancy losses ( RPL), recurrent implantation failure ( RIF) ,unexplained infertility, or advanced maternal age (>33 years in Indian women) , this number can be as high as 80%.

The genetic screening Karyotyping can identify patients at a higher risk along with detailed medical and family history.

PGT-A procedure involves using In Vitro Fertilization to develop multiple blastocyst level embryos. From every individual blastocyst 5-8 cells are removed carefully using a highly technical microscopic cell surgical procedure known as Embryo Biopsy.

The isolated cells are identified individually and Next generation sequencing analysis is conducted on each embryo’s cells by isolating DNA and running for analysis in the Chromosomal status of all 23 chromosomes of each embryo.

PGT-A reports if embryo is

• Euploid ( Normal , containing appropriate chromosomal content for all 23 chromosomes)
• Mosaic ( low to complex) – Low mosaic can have a good outcome with low chances of miscarriage (<12%) while complex mosaic could have miscarriages upto 30% per embryo and normally not transferred.
• Aneuploid : Embryo has abnormal chromosomal component in one or more chromosomes and this embryo is highly unlikely to implant and has high chance to miscarry. Aneuploid embryos are not transferred.

This report is discussed in detail at a Genetic Counselling with Our In House Genetic Expert Dr Sayali Kandari for optimal outcomes, Euploid embryos are decided to be implanted in a Frozen Embryo transfer for high chances of successful implantation!

2. Pre Implantation Genetic Testing for Monogenic diseases (PGT- M)

Over 1500 genetic disorders have been identified and can be detected in PGT-M testing

Genetic disorders coming from single gene mutations lead to children born with lethal or life debilitating diseases. In many cases genetic disorders are found in multiple members of the affected family ( hereditary diseases). But sometimes, genetic disorders can be developed for the first time in the first child of a couple which makes them aware of the risk their current and future children are exposed to.

Couples with the first genetically abnormal child can access PGT treatment to enable them to have a child free of the genetic disorder in their embryos itself. This removes the ethical and emotional trauma of undergoing medical termination after detection during pregnancy.

Many modern couples who are well informed and want to avoid any chance of genetic disorder in the first child can access Whole Exome Sequencing to evaluate if they carry any common pathogenic genetic gene . PGT-M helps to select an embryo without any abnormality in identified common pathogenic genes. PGT-M allows for peace of mind due to its high accuracy (99.8%) in detecting genetic disorders. Since 1991, Akruti IVF Center has a Senior Biopsy Professional doing Embryo Biopsies and PGT since two decades and has never reported a wrong diagnosis due to high technical precision of Genetic Team.

3. Pre Implantation Genetic Testing for Structural Rearrangements (PGT-SR) :

Chromosomal Structural aberrations or abnormalities cannot be detected using PGT Aneuploidy. It needs a special additional testing known as PGT- SR.

Structural Rearrangements can be detected in either of the parents using Genetic Karyotyping test. Once identified, a genetic counselling session is conducted to discuss the test results.

In Vitro Fertilization cycle is planned and all resultant blastocyst level embryos are biopsied.

While running the genetic tests, Next Generation Sequencing with additional testing for Structural abnormalities is conducted for each embryo’s cells.

The report normally contains reports of PGT-A for aneuploidy as well do identify normal euploid embryos alongwith the ones free of structural abnormality.

The report will provide info about Euploidy as well as presence of Structural Rearrangement

A Genetic Counselling is conducted with Our In-House Genetic expert Dr. Sayali Kandari and the identified embryo which is euploid and not contained SR abnormality can be transferred in frozen embryo transfer for maximum implantation and pregnancy success

How and when is PGT done?

Post the IVF/ICSI the embryos are obtained after 5 days & Embryo biopsy is performed with a help of advance medical laser & sample is send to the genetic laboratory for testing. On receipt of the report embryo selection is done & healthy embryo is chosen for embryo transfer.

IVF Process: The process begins with IVF/ICSI where eggs are retrieved from the female partner and fertilized in the lab using sperm from the male partner (or donor sperm in case of azoospermia)

Embryo Development: The fertilized embryos are cultured for 3-5  days until they reach the blastocyst stage, where a few cells are removed via Laser, for genetic testing.

PGT (Preimplantation Genetic Testing: The cells are analyzed for chromosomal abnormalities or genetic mutations, depending on the type of PGT being performed.

Embryo Selection: Based on the above results, the embryos free from genetic issues are selected for transferring into the uterus.