The NHS offers newborn blood spot screening when a baby is 5 days old. They are given a heel prick to take blood. If your baby has been born in one of the hospitals or areas that is offering screening for SMA, you can choose:

To have your baby screened for SMA.

If you choose this option, your baby’s information will help with making decisions about:

• adding the test permanently to newborn blood spot screening
• if added, the best way to introduce NHS screening for SMA nationally.

Not to have your baby screened for SMA.

If you choose this option, your baby can still be screened for the other conditions covered by newborn blood spot screening.

The NHS estimates that the number is more likely to be around 66 babies a year. Exact numbers are not known.

The condition causes muscle weakness and wasting (atrophy), which gets worse over time. SMA affects movement, breathing and swallowing.

Symptoms can start at different ages, from newborn to young adult.

There are four main types of SMA broadly based on when symptoms started. The impact it has varies from person to person. It can be life-threatening in the most severe cases.

Early treatment can help babies with SMA have the best chance of a healthier future.

The NHS offers newborn blood spot screening. This uses a heel prick to take blood when a baby is 5 days old. It currently looks for 10 rare but serious conditions.

Most babies will not have any of the conditions. For those who do, finding them early through screening means they can get earlier treatment. This can prevent severe disability or even save their life.

We all have 2 copies of a gene called SMN1 – one inherited from each parent.

If a baby inherits one altered SMN1 gene from each parent (a gene that is different from how it should be), they may develop SMA.

To test for SMA, the same blood sample taken during the newborn screening heel prick test is used.

There are 2 possible results – ‘SMA suspected’ and ‘SMA not suspected’:

SMA not suspected (no altered SMN1 genes)

Most babies’ blood samples do not show the altered genes that indicate SMA.

SMA suspected (altered SMN1 genes)

If your baby’s blood sample shows altered SMN1 genes this means your baby may have SMA.   If these altered genes are present, a member of a specialist clinical team will call you to arrange an urgent appointment.

They will need to see your baby as soon as possible – usually the day after they call you.

They will assess your baby and take another blood sample to confirm the results and to determine what this may mean for your baby.

The specialist team will talk to you about available treatments and offer advice and support.

Newborn screening finds  most babies with SMA. However, the test cannot detect very rare genetic changes in the SMN1 gene. These are known as point mutations. Also, this test cannot detect the extremely rare forms of SMA caused by different genes. So, while it is very unlikely, a baby can still develop SMA even if newborn tests are negative.

1. Aragon-Gawinska et al. (2023) Spinal muscular atrophy treatment in patients identified by newborn screening—A systematic review. Genes 14: 1377.
2. Belter et al (2024) Newborn Screening and Birth Prevalence for Spinal Muscular Atrophy in the US” in JAMA Pediatrics on July 15, 2024.
3. Verhaart IEC, et al. (2017) A multi-source approach to determine SMA incidence and research ready population. J Neurol 264: 1465-1473