PGT-A or PGT-M: Which is right for you?

If you’re planning to have a baby, you may be wondering what the difference is between PGT-A and PGT-M. What are they? What’s the difference? Which one is right for you?

But first, why are embryos genetically tested?

Genetic testing is frequently used to screen embryos for genetic abnormalities or conditions. A little number of cells from an embryo will be taken and sent to a genetics lab where they’ll get tested, and usually, only the genetically healthy ones are selected.  This can be helpful to those with high-risk pregnancies and those who often have frequent miscarriages.

Genetic screening technologies like PGT-A (formerly known as PGS) and PGT-M (formerly known as PGD), when combined with IVF treatment, have made it possible to minimize the risk of passing on devastating genetic diseases, possibly lower the risk of recurrent miscarriage, and improve the odds of pregnancy success. Preimplantation Genetic Testing for Aneuploidy (PGT-A) or for Monogenic disorders (PGT-M) refers to a technique where embryos obtained through an IVF cycle are assessed for genetic disorders prior to implantation.

 

What is PGT-A

Preimplantation Genetic testing for Aneuploidies (PGT A) is a genetic test performed on embryos created through IVF to screen for chromosomal abnormalities. PGT-A, formerly known as Preimplantation Genetic Screening (PGS), is used to screen embryos for extra or missing chromosomes.

PGT-A solely checks for a normal number of chromosomes within the embryo. As a woman ages, it becomes more common to see genetically abnormal embryos. Embryos can be classified as being euploid or aneuploid. In a normal situation, the egg and the sperm contribute 23 chromosomes each. Together, they make a healthy embryo with 46 chromosomes. This is called a euploid embryo.

However, if an embryo is missing a chromosome or has an extra chromosome, it is called aneuploidy. Aneuploid embryos are more likely to fail to implant or to end in miscarriage. If implantation is successful, it may lead to the birth of a child with a genetic condition.

PGT-A can also determine the gender of an embryo. Comprehensive Chromosome Screening is one technique of PGT-A that can identify whether an embryo is XX (female) or XY (male). This may be used to avoid a gender-linked genetic disorder or for family balancing.

What details will PGT-A provide?

Full aneuploidies (missing or complete extra chromosome)

Partial aneuploidies (extra or missing pieces of chromosomes)

 

PGT-M

PGT-M is a genetic test performed on embryos created through in vitro fertilization (IVF). It is designed for individuals who know they are at an increased risk of having a child with a specific genetic disorder. PGT-M was formerly known as Preimplantation Genetic Diagnosis (PGD).

It is used to test for specific genetic disorders in embryos. This type of testing is often done when there is a family history of a specific type of disorder. You can consider PGT-M if:

You and your partner are carriers of the same autosomal recessive condition (e.g. Sickle Cell Anemia, Cystic fibrosis, Gaucher disease)

You had a pregnancy or child with a single gene disorder.

You are a carrier of an X-linked disorder (e.g. Duchenne Muscular Dystrophy, Hemophillia)

You or your partner have an autosomal dominant disorder (Marfan syndrome, Huntington disease)

You or your partner have a mutation connected with a hereditary cancer syndrome (e.g. BRCA1 & 2)

 

What information will PGT-M provide?

Absence or presence of a specific genetic difference (“mutation”) that runs in the family.

 

Which type of genetic testing should I choose?

The persons who are good candidates for PGT-A are individuals who are at an increased risk for miscarriage or abnormal embryos. Most people choose to start with PGT-A and add PGT-M as an additional service.

Persons who are good candidates for PGT-M are those who are at risk of passing on a specific genetic disorder to their children.

Remember, if you have any questions or concerns about embryo testing, consult with your fertility specialist. They will be able to advise you as to which test is appropriate given your fertility history, past cycle results and specific circumstances.

At Cell Genomics, we are passionate about understanding, educating, and supporting our patients throughout their journey.

If you have any further questions regarding embryo testing, please do not hesitate to contact one of our specialists, who will be pleased to answer your questions.

 

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