Symptoms of spinal muscular atrophy (SMA)
The symptoms of spinal muscular atrophy (SMA) affect everyone differently, but can include:
- muscle weakness – such as floppy or weak arms and legs
- movement problems – such as difficulty sitting up, crawling or walking
- problems with breathing or swallowing
- twitching or shaking muscles (tremors)
- bone and joint problems – such as an unusually curved spine (scoliosis)
These symptoms are most often noticed in babies and toddlers, but they can also start in teenagers and adults.
SMA does not affect intelligence or cause learning disabilities.
Non-urgent advice: See a GP if:
- you or your child have symptoms of spinal muscular atrophy (SMA)
- you're worried about your baby or toddler's development
- you're pregnant or planning a pregnancy and someone in your or your partner's family has SMA
Types of spinal muscular atrophy (SMA)
Spinal muscular atrophy (SMA) is often grouped into types. These are based on the age that symptoms begin and how they affect sitting, standing and walking.
| Type | When it starts |
|---|---|
|
Type 1 |
Babies less than 6 months old |
|
Type 2 |
Babies and toddlers aged 6 to 17 months old |
|
Type 3 |
Children and teenagers from 18 months to 17 years old |
|
Type 4 |
Adults 18 years old and over |
How spinal muscular atrophy (SMA) affects your life
Although spinal muscular atrophy (SMA) affects everyone differently, some types are considered more severe and can affect how long someone lives.
SMA is usually more severe the earlier symptoms begin. However, the outlook for each type depends on a person's symptoms and how well treatment works.
Causes of spinal muscular atrophy (SMA)
Most types of spinal muscular atrophy (SMA) are caused by an altered gene called SMN1 being passed on to a child by their parents (inherited).
The parents do not usually have SMA themselves, which is known as "carrying" the gene. In most cases, SMA can only be passed on if both parents carry the altered gene.
If both parents carry the altered gene, there's a:
- 1 in 4 (25%) chance their child will have SMA
- 2 in 4 (50%) chance their child will carry the altered gene, but will not have SMA
- 1 in 4 (25%) chance their child will not carry the altered gene or have SMA
The chances of a child inheriting SMA can be different for some rarer types of SMA. Some rarer types are not passed on at all.
How spinal muscular atrophy (SMA) is diagnosed
If a doctor thinks your child could have spinal muscular atrophy (SMA), a blood test can be used to confirm the diagnosis.
If you're at risk of having a child with SMA, a GP may refer you to a genetic counsellor to discuss the risks and options.
Tests are available before, during and after pregnancy to see if you carry the altered gene or to confirm a diagnosis.
These tests may include:
- a genetic blood test to see if you carry the altered gene
- chorionic villus sampling (CVS) or amniocentesis tests during pregnancy to check if your baby has SMA
- a blood test after your baby is born
Treatments for spinal muscular atrophy (SMA)
There is currently no cure for spinal muscular atrophy (SMA), but there are treatments and support available to help people with SMA have the best possible quality of life.
A range of health professionals may be involved in your or your child's care. They'll help to create a care plan and advise you about which treatments are suitable for your specific needs.
Medicines for SMA
The main treatment for SMA is medicines that target the altered genes that cause SMA, including:
- nusinersen (Spinraza)
- risdiplam (Evrysdi)
- onasemnogene abeparvovec (Zolgensma)
It's not always possible to have medicines to help treat SMA. The most suitable treatments will depend on your or your child's age and symptoms. Your care team will be able to discuss the risks and benefits of any possible treatments.
Research is continuing into possible new treatments for SMA.
Treatments and support for living with SMA
Treatment and support is also available for the symptoms of SMA. Every person's needs will be different depending on their symptoms.
Support you or your child might need may include:
- physiotherapy, exercises and stretches to help maintain strength and stop joints becoming stiff
- mobility equipment (including walking frames and wheelchairs), supports for the arms or legs (splints or braces) or shoe inserts that make walking easier (orthotics)
- help with breathing problems, such as breathing exercises or machines that help clear mucus from the airways or provide air through a mask
- help with swallowing problems, such as making diet changes or using a feeding tube that's passed down the nose or attached directly through the tummy
- a back brace or surgery to help with spine problems
People with SMA are also usually advised to have the flu vaccine and pneumococcal vaccine.
Help and support for spinal muscular atrophy (SMA)
If you or your child have spinal muscular atrophy (SMA), health professionals will be there to support you throughout your treatment.
You may also find it helpful to get support from other people with SMA, or parents of children with SMA.
SMA UK
The charity SMA UK provides a range of support and information for people affected by SMA.
Recording information about you and your condition
If you or your child have spinal muscular atrophy (SMA), your care team will pass information on to the National Congenital Anomaly and Rare Disease Registration Service (NCARDRS).
This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.