The chances of having a baby with 5q SMA vary depending on whether you or your partner have 5q SMA or are carriers.

If you already have a child who has 5q SMA and your unborn baby inherits it too, they are likely to have the same type of 5q SMA. 5q SMA tends to affect siblings in a similar way, or at a similar age. But this is not always the case.

A genetic counsellor can discuss your individual genetic circumstances with you. They can give advice and information about all your testing options either before you consider any pregnancy or as early in your pregnancy as possible.

If it is possible, genetic counselling before pregnancy will give you and your partner more time to think about genetic testing and the difficult decisions this can raise. It will also support you through the emotional impact of any option you choose and discuss what the next steps might be for you and your family.

If you have a child who has SMA: you should have already been referred for Genetic Counselling. You should be able to return for further advice and support if you are thinking about a further pregnancy.

If you have SMA or are a carrier of SMA: you can be referred to your local Genetics Centre by a GP, specialist, midwife or obstetrician. If you are pregnant, you can ask for an urgent genetic counselling referral. If this isn’t possible, you can contact your local genetic service directly.

If someone in your extended family has SMA, but you do not know if you are a carrier: talk to your GP. Ask them to refer you and your partner to your regional Genetics Centre for genetic testing (see below).

You may wish to consider testing a pregnancy for SMA if:

• you and your partner are both carriers of SMA or
• one of you has SMA and the other is a carrier.

Couples may have various reasons for this. They might want to prepare for their baby’s arrival or decide to end the pregnancy.

There is a chance that a child will inherit 5q SMA if:

• both partners are carriers of SMA or
• one partner has SMA, the other is a carrier.

These options may be available to you:

• Conceive naturally and avoid any testing for SMA during a pregnancy. Your Genetic Counsellor can discuss the chances of you having a child who has SMA. If you wish, they can organise testing for the baby when they are born.
• Conceive naturally and have testing during pregnancy to see if the baby will have SMA.
• Have a type of fertility treatment which tests the embryos for SMA before achieving a pregnancy.

These options are outlined in the tabs below.

Newborn screening for SMA is not yet routine in the UK. Genetic testing for SMA at birth is not usually offered if:

• a baby shows no symptoms and
• only one parent or
• neither parent is a carrier of SMA.

If both parents are carriers of SMA, you can ask your Genetic Counsellor if your newborn baby can be tested. This is usually done by taking a cord blood sample, or a blood sample directly from the baby. Both can be done shortly after the birth of the baby. The results are usually available within 1-2 weeks. It sometimes takes longer.

If a genetic test is taken and your baby is found to have inherited SMA, the results of their test will determine whether they are eligible for one of the NHS-funded drug treatments for pre-symptomatic SMA >

It may be helpful to talk about what the treatment options would be with your genetic counsellor – or clinical team if you have one. If your genetic counsellor is not sure about the treatment options, they should contact your nearest Regional Neuromuscular Specialist Centre >.

Who can have IVF with PGT-M?

This may be an option before pregnancy for couples who:

• want to exclude the possibility of their baby having 5q SMA and / or
• may be having difficulty conceiving.

There are eligibility criteria for both the PGT-M process and for NHS funding. These overlap. Different PGT-M centres may also have different criteria. Your genetic counsellor will explain whether you are eligible.

What does IVF with PGT-M involve?

In-vitro fertilisation (IVF) is carried out using a couple’s own eggs and sperm.  Eggs are removed from the woman’s ovaries and fertilised with sperm in a laboratory.

After about 5 days, once the embryos have grown into balls of cells (‘blastocysts’), a small sample of cells is very carefully removed (an embryo ‘biopsy’). After the biopsy, the embryos are rapidly frozen (vitrification) while cells are genetically tested for 5q SMA.

If the genetic test results show at least one embryo without SMA, the medical team can select, warm, and transfer that embryo to the womb.

A pregnancy test is carried out 12 days later to see whether the PGT-M treatment has been successful.

How long does it take to get started?

There is often a wait for the initial consultation. After that starting PGT-M may be delayed while ethical approval and / or funding is arranged.

PGT-M also involves IVF (In vitro fertilisation) which also takes time. Realistically PGT-M may take many months, or sometimes even years.

Who can have NIPD?

This is an option from around the 9th week of pregnancy for couples who wish to know whether their baby has inherited SMA. This option does not involve invasive testing. There is no risk of miscarriage because of the test.

To have the test:

• Both parents must be known carriers of an SMN1 gene alteration (mutation) and
• A DNA sample must be available from:
  • the family member affected with SMA. This may be a previous child of the couple or another affected relative. If a couple has a child with SMA, there are probably lab samples from earlier tests. A new sample may not be needed or
  • a previous child of the couple who has been confirmed not to be a carrier. They do not have an altered copy of the SMN1 gene.

Testing can be done in single pregnancies but may not be possible in multiple pregnancies. This test is not currently possible for related (consanguineous) couples.

What does NIPD involve?

A sample of the mother’s blood is taken from when they are around 9 weeks pregnant. This is tested for the unborn baby’s genetic material.

The test result should be available within 21 days. Results are often available quicker than this.

What will the NIPD Test Show?

The NIPD testing will show whether the foetus has inherited the affected or unaffected copies of the SMN1 gene from each parent.

• If the foetus has inherited one affected copy of the SMN1 gene, and one unaffected copy, they are a carrier of 5q SMA.  They are very unlikely to be affected.
• If the foetus has inherited two affected copies of the SMN1 gene – one from each parent – the child will have 5q SMA.

Very occasionally, the test may not return a result. If this happens the test may be repeated or an alternative invasive test may be carried out. See CVS and amniocentesis below.

When using NIPD, there is a small, estimated risk of misdiagnosis. This is approximately 1 in every 500-1000 diagnoses. This is due to technical and biological reasons.

What Next?

You would be given information and support before, during and after your NIPD treatment. This will help you decide what to do next. Your options at this point would be to continue with or end the pregnancy. There are different ways to do this depending on the stage of the pregnancy.

How can I access this test?

Access to this testing and genetic counselling is through your local genetics centre, wherever you live in the UK. Your genetics centre will be able to advise you on funding and charges for NIPD.

Who can have CVS?

This is an option for couples who wish to know if their baby has SMA. It is usually carried out between the 11th and 14th weeks of pregnancy. It is sometimes performed later than this if necessary.

What does CVS involve?

CVS involves taking a sample of the placenta and testing the cells for 5q SMA. This involves either inserting a needle through the abdomen (transabdominal CVS) or inserting a tube through the cervix (transcervical CVS). Both processes are guided by a scanner.

The sample is sent to a laboratory and genetically tested for 5q SMA. It cannot show the Type of 5q SMA, although the laboratory may also test for SMN2 copy number.  This can help your genetics team to predict how severe the SMA symptoms might be.

It generally takes a week for the test result, but this may vary. You can ask how long it will take for the result and decide how you will be informed.

CVS can cause miscarriage, the loss of the pregnancy in the first 23 weeks. The chance of miscarrying after CVS is thought to be less than 1 in 200 for most pregnancies, and at around 1 in 100 for multiple pregnancies (such as twins).

What Next?

You would be given information and support before, during and after your CVS treatment to help you decide what to do next. Your options at this point would be to continue with or end the pregnancy. There are different ways to do this depending on the stage of the pregnancy.

This is an option usually between the 15th and 20th weeks of pregnancy for couples who wish to know whether their baby has SMA.

What does amniocentesis involve?

Amniocentesis involves putting a needle through the abdomen to remove some of the fluid that surrounds the foetus in the womb (amniotic fluid). The cells in the amniotic fluid are sent to a laboratory and genetically tested for 5q SMA. It cannot show the Type of SMA, although the laboratory may also test for SMN2 copy number. This can help your genetics team to predict how severe the SMA symptoms might be. The test results are usually available in around 1-2 weeks. You can ask how long it will take for your result and decide how you will be informed.

Amniocentesis can cause miscarriage, the loss of the pregnancy in the first 23 weeks. This is estimated to occur in up to 1 out of every 200 women who have amniocentesis. The risk of amniocentesis causing complications is higher if it is carried out before the 15th week of pregnancy. This is why the test is only done after this point.

What Next?

You would be given information and support before, during and after your amniocentesis to help you decide what to do next. Your options at this point would be to continue with or end the pregnancy. There are different ways to do this depending on the stage of the pregnancy.

This is an option before pregnancy. It may be available for couples who:

• want to exclude the possibility of their baby having 5q SMA and / or
• may be having difficulty conceiving.

What does IVF involve?

During IVF, an egg is removed from a woman’s ovaries and fertilised with sperm in a laboratory. After a few days, the fertilised egg, called an embryo, is then transferred into the prospective mother’s womb. There is then a 2 week wait for a pregnancy test to see if the treatment has worked.

Depending on a couple’s circumstances, IVF would be carried out using eggs and / or sperm from donors who have been tested to check that they are not carriers of 5q SMA.

Your genetic counsellor will be able to discuss whether this could be an option for you.

Antenatal Results and Choices (ARC)

ARC > is a national charity helping parents and healthcare professionals through antenatal screening and its consequences. They offer non-directive information and support to parents:

• before, during and after antenatal screening
• if their baby has a diagnosis
• if they are making difficult decisions about continuing with or ending a pregnancy
• if they are coping with complex and painful issues after making a decision, including bereavement.

Helpline: 0207 713 7486
Email: info@arc-uk.org
Text: 07908 683004

Miscarriage Association

The Miscarriage Association > information and support for anyone affected by miscarriage. Helpline: 01924 200 799

SMA UK

SMA UK provides free, confidential information and support to anyone affected by SMA. We do not offer a counselling service and aren’t experts in terms of family planning options but we’re always willing to listen and offer emotional support. Phone: 01789 267520 or contact our Support Team >.