Pre-implantation genetic testing for monogenic disorders (PGT-M) and Pre-implantation genetic testing for chromosomal structural rearrangements (PGT-SR)

What is PGT-M?

PGT-M, previously known as preimplantation genetic diagnosis (PGD), is a treatment which involves checking the genes or chromosomes of your embryos for a specific genetic condition.

Because the embryos need to be tested in a lab, you will need to have IVF, even if you and your partner have no fertility problems.

Embryos which have been tested and are free of the condition will be placed back into your womb to hopefully continue to develop. Historically, the embryo was usually transferred two to six days after being created (ie, a fresh embryo transfer) but now, the embryo is more often frozen and transferred at a later date.

Find out more about IVF

What is PGT-SR?

PGT-SR is a treatment that involves looking at the chromosome structure of your embryos, and finding where segments may have been deleted, duplicated or inverted. It can be used for people with a known chromosome structural rearrangement, to improve the chance of a healthy pregnancy.

Who can have PGT-M or PGT-SR?

Your doctor may discuss PGT-M or PGT-SR with you if:

• you have ended previous pregnancies because of a serious genetic condition
• you already have a child with a serious genetic condition and want to avoid this happening again
• you have a family history of a serious genetic condition
• you have a family history of chromosome problems or
• you have a history of recurrent miscarriage due to chromosomal abnormalities

Which genetic conditions can be tested for with PGT-M?

It is possible to use PGT-M to test for almost any genetic condition where a specific gene is known to cause that condition. However conditions can only be tested for when the condition has been considered by the Authority to comply with legal criteria related to the risk of transmission and the seriousness of symptoms, in somebody affected by the genetic abnormality to be tested for.

List of conditions you can test for

Which genetic conditions can be tested for with PGT-SR?

Chromosomal rearrangements such as duplications, deletions and inversions, can disrupt embryo development to the extent that a pregnancy is lost or a baby is born with significant developmental defects. The Authority has approved ‘Chromosomal rearrangements (various)’ as a condition for which embryo testing can be applied, if a case complies with legal criteria related to the risk of transmission and the seriousness of symptoms in somebody affected by the genetic abnormality to be tested for.

Therefore in those at risk of transmitting a chromosomal abnormality which can cause repetitive pregnancy failure or developmental defects, PGT-SR can be used to achieve a success pregnancy.

What if I have a genetic condition that hasn't been approved for testing?

If there’s a genetic condition you’d like to be able to test for that hasn’t already been approved, your clinic will need to apply to us to add it to the PGT-M list.

There are strict criteria for deciding which conditions should be permitted so bear in mind it could be a lengthy process and you may not be successful.

Read our guidance on embryo testing for clinics

Learn more about the HFEA’s PGT-M application process

Find a PGT-M clinic near you

How safe is PGT-M and PGT-SR?

PGT-M and PGT-SR treatment is thought to be very safe – there is no evidence that babies born following such treatments suffer from any more health or developmental problems than babies born using IVF alone. There are risks from having IVF though.

Find out more about the risks of IVF

Although an embryo can usually develop normally even when it has had some cells removed, there is a possibility that some embryos may be damaged by testing, which means they would need to be discarded and wouldn’t be able to be used in IVF treatment. In addition, PGT-M and PGT-SR are not 100% accurate so there’s a small chance the tests may not work or may give the wrong information.

What’s the chance of having a baby?

As with most fertility treatments, success depends on many factors, including the woman’s age and whether there are any existing fertility problems.

While numbers of treatments being carried out are still low, PGT-M and PGT-SR embryo testing has become more popular.

For the latest statistics on PGT-M and PGT-SR visit our Research and data page.

Why might PGT-M and PGT-SR be unsuccessful?

Unfortunately, sometimes there are no embryos suitable for transfer to the womb. This could be because:

• not enough eggs are produced or fertilised in the first place
• there is a small risk that removing the cells for analysis damages an embryo
• all the embryos are affected by the genetic abnormality

How can I get PGT-M or PGT-SR treatment?

Your first step should be to talk to your GP, who will refer you to a Regional Clinical Genetics Service for further advice about all your options.

In some cases, you can get PGT-M or PGT-SR treatment on the NHS but it depends on your situation and where you live – your GP should be able to advise you.

If it’s been agreed that PGT-M or PGT-SR is the right treatment for you, you’ll be referred to a specialist at a fertility clinic that has a licence from us to carry out embryo testing treatments. This is a specialist service so your nearest clinic may be far away. Please note that PGT-M and PGT-SR are together referred to as PGD on our Choose a clinic page.

Choose a clinic

You can also find a list of Regional Clinical Genetics Services in your area by visiting the Genetic Alliance UK website.