Preimplantation Genetic Testing Preimplantation genetic testing (PGT) is a suite of genetic tests that may be performed on one or more of your embryos prior to transfer to ensure use of the best-quality embryo available and avoid transferring embryos with a higher likelihood of implantation failure.

What is PGT for?

PGT assesses an embryo formed through IVF or ICSI for genetic abnormalities. Genetic problems, such as missing or extra chromosomes, can increase the risk of a pregnancy loss or having a baby affected by a genetic disorder. Identifying chromosomal abnormalities early on can give you additional peace of mind.

Dr Sacks may suggest PGT if you:

Have experienced recurrent miscarriages
Have a family history of a genetic condition
Are of advanced maternal age
Have not been successful so far with IVF
Have a known chromosomal rearrangement
Are a known carrier of a genetic disorder

Types of PGT

Different types of PGT are suited for different situations.

PGT-A: preimplantation genetic testing for aneuploidies

An aneuploidy means your embryo has an abnormal number of chromosomes, whether too many or too few. Down syndrome is an example of an aneuploidy, where there is an extra copy of chromosome 21.

PGT-A is suitable for those who have a higher risk of passing on an aneuploid sperm or egg, including people who have had a previous pregnancy with aneuploidy, or if you’ve experienced recurrent pregnancy losses or implantation failures.

PGT-M: preimplantation genetic testing for monogenic conditions

A monogenic condition is a disorder caused by variation in a single gene. Huntington disease, cystic fibrosis, and Duchenne muscular dystrophy are examples of inheritable diseases arising from one abnormal gene.

If you have a single-gene condition yourself or in your family, or know that you are a carrier of a gene mutation, PGT-M may be suitable for you.

PGT-SR: preimplantation genetic testing for structural rearrangements

Individuals with a structural rearrangement have the correct amount of chromosomal material organised in a different order. This might mean two chromosomes have broken off at a point and swapped sections, or that a piece of one chromosome has attached itself to the end of another. Though you are not affected by this mild abnormality, it does increase the chances of your embryo inheriting an abnormal amount of genetic material through your egg or sperm. This raises the risk of a miscarriage or your baby being affected by a genetic disorder.

PGT-SR is appropriate for couples where one or both partners has a known chromosomal rearrangement.

How does PGT work?

Preimplantation genetic testing is only available on embryos that have been developed through IVF or ICSI. In order to assess your embryo’s genetic material, a tiny biopsy is taken from the outer layer of placenta cells and assessed by one of the experienced geneticists at Genea Fertility.

The information gained from PGT can be instrumental in maximising your chances of a successful IVF or ICSI cycle, especially if you have any of the factors known to increase the risk of passing on a genetic problem to your embryos.

Frequently Asked Questions

What happens if the PGT results show a genetic abnormality?

If our genetic testing identifies that an embryo has a genetic problem, this embryo will not be selected for transfer and implantation. In most cases, embryos with a chromosomal abnormality will be discarded with your consent.

If PGT shows that my embryo is normal, does that guarantee my baby will be healthy?

While a normal PGT result increases the likelihood of a healthy baby, we still need to consider that PGT is not 100% accurate and there is a very low chance it may return false negative results (indicating that the embryo is normal when there is a genetic abnormality present). There may also be genetic conditions not covered by the test or complex factors that are beyond our current knowledge.

Does PGT have risks?

There is a very low chance of accidental damage to the embryo when taking the biopsy (approximately 5%). However, having PGT done on an embryo does not increase the likelihood of having a baby with a birth defect or increased health risks. The cells taken for the biopsy are those that will develop into the placenta, not those that will form the foetus itself.