Preimplantation Genetic Testing (PGT)

There are a variety of tests we use to test fertility patients and their embryos for potential chromosomal or genetic abnormalities. The first, called preconception genetic screening, is recommended during the infertility testing process and before creating your fertility treatment plan. It determines whether one or both partners may be carriers of some of the most common chromosomal/genetic issues that negatively impact conception or a full-term pregnancy.

The second type, preimplantation genetic testing (PGT), is a state-of-the-art procedure used in conjunction with in vitro fertilization (IVF) to screen embryos for the appropriate number of chromosomes or specific genetic abnormalities. Some of the most common chromosomal or genetic conditions we test for include:

• Chromosomal abnormalities.
• Sickle cell disease.
• Tay-Sachs disease.
• Cystic fibrosis
• Fragile X syndrome
• BRCA1/2-related hereditary cancers
• Huntington disease.
• Spinal muscular atrophy

These genetic conditions can interfere with embryo implantation, result in recurrent pregnancy loss, or in the birth of a child with physical problems, significant developmental delays, or mental retardation.

PGT is Performed on Blastocysts (Embryos)

PGT is performed in conjunction with an in-vitro fertilization cycle where multiple eggs are produced, retrieved from the ovaries, and fertilized with sperm in the IVF laboratory.  Several days after egg retrieval, we remove from each cell through a procedure called embryo biopsy. These cells are sent to an outside laboratory and analyzed via one or more of three PGT options.

To view a sample PGT-P report, click here.

PGT is not part of the IVF protocol. Rather, potential indications that you’re a candidate for PGT include:

• Inherited genetic disorders
• Recurrent Miscarriage
• Advanced Maternal Age
• Unexplained Infertility
• Unsuccessful IVF Cycles

Genetic testing of the embryo may reduce the potential for adverse pregnancy outcomes for couples “at risk” by enabling us to test the embryos for specific genetic abnormalities before being selected for transfer during IVF.

For example: Four embryos resulted from an IVF cycle, and through PGT testing, two were identified as genetically abnormal, while two were normal. Armed with this knowledge, only the normal embryos would be selected for embryo transfer, thereby potentially reducing the possibility of miscarriage or birth defects.

It is important to remember that PGT is considered a screening test.  Please, discuss in detail the risks, benefits, and alternatives to this testing option with your physician.

Three PGT Test Options

We typically use one or more of three PGT tests:

PGT-A+ (Aneuploidy)

PGT-A+ testing identifies any spontaneous abnormalities in chromosome numbers or structures. Spontaneous means that both parents have healthy chromosomal pairs, but their offspring may not depending on a variety of factors.

Healthy humans have 23 pairs of intact chromosomes, which means 46 total chromosomes. Half are contributed by the sperm, and the other half from the egg.

Sometimes, during the complex conception process, chromosomes can be:

• Missing.
• Broken.
• Extra.

Any variation from the normal, intact 46 chromosomes is called aneuploidy and accounts for roughly 60% of all pregnancy loss – as well as a significant number of the most common congenital disorders, like trisomy or Down Syndrome.

Using PGT-A+ tests gives us more information about which embryos seem the healthiest for transfer. This can mean higher pregnancy rates in certain populations. It can also reduce the risk of miscarriage.

PGT-M (monogenic)

This test is only used when you’re using your own egg and/or sperm, and there is a risk of passing on a monogenetic disorder. A monogenetic disorder passes from paren to offspring due to a variation in a single gene.

You would usually only use PGT-M if you:

• And your partner were both identified as carriers of the same genetic disorder during preconception genetic screening.
• Have a personal or family history of monogenetic disorder(s).
• Have had a child diagnosed with a monogenetic disorder in the past.
• Your pursuing IVF because of an interest in HLA matching.

PGT-SR (structural rearrangements)

This is the least commonly recommended type of preconception genetic testing. This test is done to identify any non-spontaneous structural rearrangements of the chromosomes. Therefore, it’s different from the chromosomal testing performed via PGT-A+ (see above).

Sometimes, a parent contributing their eggs or sperm can have a chromosomal abnormality that doesn’t show up via phenotype (how they look) or other symptoms. However, because half of their chromosomes are shared, their children can inherit the disorder.

PGT-SR looks for embryos that have missing or extra genetic material. In most cases, you would not use PGT-SR unless your physician, genetic counselor, or fertility specialist recommends doing so.

Discuss Whether You’re a Candidate for PGT With the Reproductive Resource Center

It is important to remember that PGT is considered a screening test – and the results are not 100% accurate.  Please discuss the risks, benefits, and alternatives to these testing options in detail with your physician.

Do you feel you’re a candidate for PGT to increase your chances of IVF success? Schedule a consultation with the Reproductive Resource Center of Kansas City. We are dedicated to impeccable infertility testing so we can get accurate results. From there, we will determine whether you’re a good candidate for PGT. Contact us to schedule an infertility consultation.