August is Spinal Muscular Atrophy (SMA) Awareness Month: Educate, Support, Research
In August, we recognize Spinal Muscular Atrophy (SMA) Awareness Month, with the following goals:
Education: Inform the public about SMA, its symptoms, diagnosis, and treatment options.
Support: Provide resources and support to individuals and families affected by SMA.
Research: Promote research and development of new treatments and therapies to improve the lives of those living with SMA.
What is SMA?
Spinal muscular atrophy (SMA) is a genetic condition that affects the motor neurons, causing progressive muscle weakness and wasting (atrophy). SMA is also called 5q SMA. This is because, in most cases, SMA is caused by a change in the SMN1 gene located on chromosome 5 (5q). 5q SMA has traditionally been classified into type 1, 2, 3, and 4, based on when symptoms appear and how severe they are. Type 0 is a rare and very severe form with symptoms developing before birth. SMA can be diagnosed through genetic testing in pre-symptomatic stages.
Treatments are available for pre-symptomatic cases and SMA types 1, 2, and 3, if people meet the eligibility criteria. These treatments are most effective if given before muscle weakness sets in; they can slow the progression of muscle weakness and may improve strength and motor function.
Symptoms of spinal muscular atrophy
SMA type 1
Symptoms of SMA type 1 typically appear within a child’s first six months. This type is the most common and severe form of SMA. Babies and children with SMA type 1:
Present as a ‘floppy baby’ due to low muscle tone and severe muscle weakness.
May be unable to raise their head because of weak neck muscles.
Are unable to sit without support because of weak core muscles.
May have difficulty moving, breathing, and swallowing.
Are at higher risk of respiratory issues and chest infections.
While many children with SMA type 1 have typical learning and thinking abilities and are alert and responsive, some may experience cognitive impairment and developmental delay.
Without medical intervention, symptoms progress quickly, with life expectancy estimated at less than two years. However, improved standards of care and new treatments are helping to extend life expectancy and improve quality of life for these children.
SMA type 2
Symptoms of SMA type 2 typically appear between the ages of 6 and 18 months. Generally, the earlier the onset, the more severe the condition. People with SMA type 2 may:
Be able to sit independently but not be able to walk.
Have muscle weakness that affects both arms and legs, with the legs often weaker.
Be prone to scoliosis.
Experience twitching or tremors in the tongue or hands.
Have breathing problems that may worsen during infections.
Progression of SMA type 2 can vary. While it may affect life expectancy in some cases, improvements in care and new treatments mean that many people are now living well into adulthood and enjoying a good quality of life.
SMA type 3
Symptoms of SMA type 3 typically appear from 18 months to early adulthood. People with SMA type 3 may:
Be able to stand and walk independently at first, though they may find walking, balancing, and getting up from a seated position difficult.
Experience progressive muscle weakness, mainly in the legs, which may eventually limit mobility.
Have a lower risk of respiratory problems compared to earlier-onset types, though these can still occur.
If untreated, gradual loss of mobility and increased weakness are common; however, with adaptive support and therapy, many people with SMA type 3 are able to maintain independence for a significant amount of time. Life expectancy is generally considered to be unaffected.
SMA type 4
Symptoms of SMA type 4 typically appear in adulthood and tend to be milder. People with SMA type 4:
Experience gradual muscle weakness in the arms and legs, affecting mobility and daily tasks over time.
May feel tired and have aching muscles, cramps, or numbness.
Rarely have issues with swallowing or breathing.
Progression is typically slow, and life expectancy is unaffected. Symptoms can be managed well with therapy and support.
It’s important not to confuse SMA type 4 with the progressive muscular atrophy form of motor neurone disease (MND). MND tends to get worse quickly and can be life-threatening, while SMA type 4 progresses slowly and people usually have a normal life expectancy.
Rarer forms of SMA
There are rarer forms of SMA caused by different genetic changes, which result in different patterns of symptoms and progression. These rarer forms are not part of 5q SMA, and don’t fall into the typical classifications of types 1 to 4, but they still affect the motor neurons. Some rarer forms include SMA with respiratory distress type 1 (SMARD1), X-Linked SMA, spinal and bulbar muscular atrophy (SBMA, or Kennedy’s disease), and spinal muscular atrophy with lower extremity dominance (SMALED).