Scotland has become the first UK nation to screen all newborn babies for spinal muscular atrophy. Here is what you need to know.
What is spinal muscular atrophy and how does it affect babies?
Spinal muscular atrophy is a motor neurone disease that starts during infancy. There are different types of SMA, which vary in how severely they affect the child. The most severe type of SMA is, sadly, the most common. Untreated, babies with the most severe types of SMA would not be expected to live to their second birthday.
The disease happens because the body can’t make enough of a protein needed to keep the nerves that control muscles alive. As these nerve cells are lost, muscles become weak, making it hard for babies or children to move, swallow or breathe.
How common is SMA in the UK, and why is it considered a serious condition?
SMA is classed as a “rare” condition. However, for a rare condition, it is quite common. It affects around one in 14,000 births in the UK each year. Each month, around four babies with SMA are born in the UK. It is considered serious as, untreated, babies and children would die or experience serious lifelong disability.
What is the heel prick test?
The heel prick test (also called a “blood spot test”) is already routinely performed on babies born in the UK. During this test, a small sample of blood is taken and it is used to screen for a variety of genetic diseases.
If SMA is caught at birth, can it be cured?
There is no cure for SMA, but there are treatments that aim to fix the underlying genetic problem. The treatments for SMA are much more effective when given as early as possible. When treatment is delayed, it can still be beneficial. However, children may still have difficulty standing or walking, and experience lifelong difficulties with basic functions such as breathing and eating. However, with early treatment, any remaining difficulties are likely to be milder.
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How could adding SMA to routine newborn screening change children’s lives?
The ability to detect SMA in newborns means diagnosis can happen before symptoms appear. Without screening, it may take months to reach a diagnosis.
With screening, SMA can be identified within the first week of life, allowing treatment to begin soon after. If therapy is started early enough, some children may never develop obvious symptoms and can reach milestones such as sitting, crawling and walking at the same pace as their peers.
The early window matters because motor neurons – the nerve cells that control muscle movement – are rapidly lost in SMA and cannot be replaced. Starting treatment as soon as possible helps preserve these cells, slowing or even halting disease progression. The more motor neurons that remain, the better the outcome for the child.
Have other countries implemented SMA screening?
Yes. For instance, the first state in the US started screening for SMA in 2017. All 50 states in the US were screening for SMA by 2024, as were most European countries. There is a huge body of evidence that earlier treatment leads to better outcomes.
How has medical progress changed life expectancy and quality of life for children with SMA?
Medical progress has revolutionised life for people with SMA and their families. In the past, a diagnosis of SMA usually meant a very short life expectancy, or lifelong profound disability, with a high reliance on caregivers for even the most basic bodily functions.
Treatments for SMA have given huge hope to the SMA community. The treatments have the capacity to stop the progression of the disease, allowing many children who would previously not have survived to live longer, and preventing further decline in muscle strength for those living with the disease.
Could this lead to screening for more rare genetic conditions in newborns?
SMA has been added to newborn screening because effective treatments are now available. The technology behind these treatments could also be adapted to tackle other genetic conditions in the future. There is a great deal to learn from progress in SMA, from how these therapies were developed to how screening programmes were successfully introduced.
Lyndsay Murray receives funding from Cure SMA, the SMA Foundation, Muscular Dystrophy UK, Motor Neuron Disease Scotland and the Anatomical Society.
