PGT-SR: Testing Embryos | Newlife IVF
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PGT-SR

Preimplantation genetic testing for chromosomal structural rearrangements is a technique that allows us to assess an embryo for chromosomal rearrangements, thus reducing the risk that these rearrangements will be passed on to your offspring. Formerly, PGT-SR was known as preimplantation genetic diagnosis (PGD).

Why is the genetic material tested?

Each one of us has a genetic blueprint — an ‘instruction manual’ that makes us uniquely human and determines our individual characteristics. This blueprint is contained in every cell of our bodies and is packaged into structures called chromosomes. Normally, there are 46 chromosomes — 23 are inherited from the mother and 23 are inherited from the father.

Chromosomal rearrangements refer to changes in the normal arrangement or size of a person’s chromosomes. People that have chromosomal rearrangements may not be affected – their chromosomes may be rearranged, but overall, they may still have a normal amount of genetic material. However, people with chromosomal rearrangements have an increased risk of creating an embryo with an incorrect amount of genetic material. In most circumstances, an incorrect amount of genetic material is incompatible with life. If these abnormal embryos are transferred, they fail to implant successfully or miscarry. However, some abnormal embryos can carry through to birth and result in a baby with a genetic disorder.

What exactly is PGT-SR?

PGT-SR involves taking a biopsy of the embryo (5–7 cells from the outer layer) after it has grown and developed for 5–6 days. From this sample, we can analyse the genetic material of the embryo and determine whether a chromosomal rearrangement is present in the DNA or not. In this way, we can prevent the transfer of embryos that have a chromosomal rearrangement.

What are the risks of PGT-SR?

PDT-SR does carry some risks, including:

Risk of harm to the embryo

Embryos are fragile, so any procedure that involves handling the embryo and disturbing its surrounding conditions poses the risk of harm. However, while the risk of harm will always exist, it is thought that the overall risk of damage to the embryo is minimal.

Inaccuracy of the test

When we conduct testing on a sample of cells from the embryo, we are assuming that this sample is representative of all the cells in the embryo. However, a condition called mosaicism may exist, where some of the embryo’s cells have the chromosomal rearrangement and some of the cells do not. Testing of embryos that display mosaicism can result in an inaccurate or unclear test result.

Indeterminate results

The results of the genetic testing may return as ‘indeterminant’, meaning the test could not determine whether the genetic material of the embryo was normal, or abnormal. This may occur for a variety of reasons, including a poor-quality embryo.

Who do we recommend PGT-SR for?

We may recommend PGT-SR if you or your partner carry a chromosomal rearrangement. We may also recommend PGT-SR if you have previously had a child or pregnancy affected by a chromosomal rearrangement.

Feasibility testing is also required prior to PGT-SR to see if your particular chromosomal rearrangement can be tested for. Your Newlife IVF fertility specialist will assess the specifics of your situation with you and make a recommendation accordingly.

What is the cost of PGT-SR?

At Newlife IVF, PGT-SR currently costs $780 per embryo.* You can visit our fees page for more information but for PGT pricing specific to your circumstances, please contact us.

*Fees correct as of 1 January 2024; reduced rates may apply depending on eligibility (in line with new Medicare rebates effective 1 November 2021), as well as number of embryos tested.

Frequently asked questions

  • What is PGT?

    Preimplantation genetic testing (PGT) is a broad term for a range of scientific techniques available during IVF to identify genetic abnormalities in embryos before they are transferred into the uterus.

    PGT may be requested by couples or individuals who are at risk of passing on a genetic condition or structural chromosome rearrangement to their offspring. PGT may also be used to assess the number of chromosomes in an embryo.

  • What is PGT-SR?

    PGT-SR is a genetic test for your embryo designed to check for a known structural chromosome rearrangement in your family, such as a translocation (when a chromosome breaks and the fragmented segments re-attach to different chromosomes). It can be used to reduce the risk of miscarriage or the birth of a child with a chromosome abnormality.

  • How is PGT-SR different to PGT-A?

    PGT-A can be used by any individual or couple during IVF to check the number of chromosomes in an embryo.

    Whereas, PGT-SR is used when one biological parent carries a structural chromosome rearrangement and there is an increased risk of a chromosome abnormality in their embryo.

  • Can you perform PGT-A and PGT-SR?

    Yes, it is possible to perform both preimplantation genetic testing for aneuploidies (PGT-A) and preimplantation genetic testing for a structural chromosome rearrangement (PGT-SR) on the same embryo.

    In fact, performing both PGT-A and PGT-SR on embryos can provide a more comprehensive evaluation of their genetic health. At Newlife IVF, all embryos evaluated using PGT-SR also receive PGT-A.

  • How is PGT-SR performed?

    Once an embryo (created as part of an IVF cycle) has reached the blastocyst stage (usually after 5–6 days of growth), a few cells are removed from the embryo. The cells obtained are then analysed using the PGT-SR technique. Based on the results, your genetic counsellor and fertility specialist can advise which embryos are suitable to transfer into your uterus.

  • What are the benefits of PGT-SR?

    PGT-SR allows couples and individuals to identify embryos with balanced (where the complete chromosome set is still present though rearranged) or normal chromosome arrangements. These embryos have a higher chance of successful implantation and a lower risk of miscarriage or chromosome abnormalities developing in children. It allows individuals or couples with a structural chromosome rearrangement to conceive healthy pregnancies with reduced risks.

  • What are the limitations of PGT-SR?

    PGT-SR is a highly accurate screening test. However, it’s not without some limitations. For instance, not all embryos will reach the blastocyst stage needed for biopsy to perform PGT-SR. Additionally, the lab may not obtain a result for every embryo biopsied. In some instances, the lab is unable to distinguish between an embryo with a balanced structural chromosome rearrangement (where the complete chromosome set is still present though rearranged) or a normal chromosome arrangement. There is also a small potential for a false positive or false negative result.

  • Can PGT-SR be combined with other forms of preimplantation genetic testing?

    PGT-SR can be combined with other forms of preimplantation genetic testing, such as preimplantation genetic testing for aneuploidy (PGT-A) or preimplantation genetic testing for monogenic (single gene) conditions (PGT-M). PGT-A, which screens for chromosome abnormalities in embryos, is included for all patients having PGT-SR. PGT-M, which screens for genetic conditions or single gene variants, is an option for individuals or couples with an increased risk of passing a genetic condition onto their offspring.

  • What happens after PGT-SR?

    PGT-SR embryos identified as having balanced or normal chromosomal arrangements are selected for transfer into the uterus. Any remaining embryos with unbalanced chromosome rearrangements will be discarded. Genetic counselling sessions are available to discuss the implications of PGT-SR results.

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For more information or to book an appointment with one of our fertility doctors, please call (03) 8080 8933 or email [email protected]. Fertility appointments can also be booked via our online booking page.

Our three Melbourne clinics are based in Box Hill, Clayton and East Melbourne and are open Monday–Friday: 8:00am–5:00pm. We welcome patients from all over Victoria, as well as those seeking care interstate or internationally. All fertility treatment requiring day surgery or lab access (e.g. egg collection, embryo transfer) will take place at our state-of-the-art treatment centre in Box Hill. Fertility consultations and IVF cycle monitoring can be arranged at all three Melbourne clinics.

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