SMA Questions

Approximately 1 in every 10,000 people are born with SMA.¹

1. D'Amico A et al. Spinal muscular atrophy. Orphanet J Rare Dis. 2011;6:71.

Approximately 95–98% of SMA diagnoses are cause by mutations to the SMN1 genes.¹ This is known by neurologists and researchers as “5q SMA”. There are other, rarer, forms of SMA that may have similar symptoms. A neurologist will include these other conditions in their differential diagnosis.

1. Prior TW et al. Spinal muscular atrophy. NCBI Bookshelf Website. Available at https://www.ncbi.nlm.nih.gov/books/NBK1352/ (Accessed February 2023).

The time until symptoms first appear can vary according to SMA type, but the genetic mutations that cause SMA are present before birth. SMA type 4 is an adult-onset form of SMA and symptom onset is generally around 30 years of age.¹

1. Farrar MA et al. Emerging therapies and challenges in spinal muscular atrophy. Ann Neurol. 2017;81(3):355-368.

SMA carriers do not have signs and symptoms of SMA. The only way to determine SMA carrier status is with a genetic test. It is thought that approximately 1 in 35 people are SMA carriers.^1,2 However, individuals with a family history of SMA may have an increased risk of being an SMA carrier.

In making reproductive decisions, it may be helpful to consult with your physician to learn what mutation(s) are common in your family, and what appropriate tests may be required to detect these. Once your family mutation(s) are known, an appropriate test for your situation may be determined.

References:
1. Butchbach M. Front Mol Biosci 2016; 3: 7.
2. Kaczmarek A et al. Expert Opin Investig Drugs 2015; 24: 867–81.

If both parents are SMA carriers, there is a 1 in 4 chance their child will have SMA. It may be helpful to consult your doctor about reproductive decisions and whether SMA carrier screening would be useful.

Yes, babies and infants can have SMA. These individuals are most likely to have infantile-onset (Type 1) SMA. Symptoms can include muscle weakness, inability to hold head up or control head movements, or hypotonia (low muscle tone that may make a baby appear “floppy”).¹

If you are concerned about your child’s development, please speak to your doctor or nurse as soon as possible as this may lead to an earlier diagnosis of SMA, which can improve outcomes.

1. D'Amico A et al. Spinal muscular atrophy. Orphanet J Rare Dis. 2011;6:71.

Adult or type 4 SMA develops later in life, around 30 years of age.¹ This is the mildest type of SMA and individuals may experience some muscle weakness but keep the ability to walk.²

Children who are diagnosed with SMA and grow into adulthood will experience a different care journey than individuals who are diagnosed as adults.

1. Farrar MA et al. Emerging therapies and challenges in spinal muscular atrophy. Ann Neurol. 2017;81(3):355-368.
2. Prior TW et al. Spinal muscular atrophy. NCBI Bookshelf Website. Available at https://www.ncbi.nlm.nih.gov/books/NBK1352/ (Accessed February 2023).

SMA is not a curable condition yet. However, some therapies may be able to slow the progress of SMA, and different types of care (for breathing and bone health, for example) can help with motor function.

1. Mercuri E et al. Diagnosis and management of spinal muscular atrophy: Part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care. Neuromuscul Disord. 2018;28(2):103-115.
2. Finkel RS et al. Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord. 2018;28(3):197-207.

SMA is diagnosed by a paediatric neurologist in children, and an adult neurologist in adults. Whether an individual with SMA will need to see additional specialists depends on the type and level of care they may require. Individuals with SMA may have a multidisciplinary care team that includes, for example: a neurologist, a respiratory specialist, a dietitian and/or a nutritionist, a physiotherapist, and an orthopaedic surgeon.^1,2

1. Mercuri E et al. Diagnosis and management of spinal muscular atrophy: Part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care. Neuromuscul Disord. 2018;28(2):103-115.
2. Finkel RS et al. Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord. 2018;28(3):197-207.

SMA can affect individuals differently, depending on the type and severity of SMA. Changes to motor function over time can affect an individual’s ability to sit or walk unassisted, fine motor skills such as using a pen, and in severe cases, the ability to eat and swallow.¹

1. D'Amico A et al. Spinal muscular atrophy. Orphanet J Rare Dis. 2011;6:71.

SMA is a progressive neuromuscular condition. In the absence of survival motor neuron (SMN) protein, motor neurons deteriorate and muscles atrophy. Progressive muscle weakness can lead to changes in motor function, such as losing the ability to sit unassisted. Care in SMA is focused on maintaining motor function and health among individuals with SMA.

1. D'Amico A et al. Spinal muscular atrophy. Orphanet J Rare Dis. 2011;6:71.
2. Mercuri E et al. Diagnosis and management of spinal muscular atrophy: Part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care. Neuromuscul Disord. 2018;28(2):103-115.
3. Finkel RS et al. Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord. 2018;28(3):197-207.

Physiotherapy can be an important part of managing SMA. A physiotherapist will determine an individual’s ability and functional level, and then help choose exercises that are suitable and safe for the individual. 

SMA is diagnosed by a paediatric neurologist in children, and an adult neurologist in adults. Whether an individual with SMA will need to see additional specialists depends on the type and level of care they may require. Individuals with SMA may have a multidisciplinary care team that includes, for example: a neurologist, a respiratory specialist, a dietitian and/or a nutritionist, a physiotherapist, and an orthopaedic surgeon.^1,2

1. Mercuri E et al. Diagnosis and management of spinal muscular atrophy: Part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care. Neuromuscul Disord. 2018;28(2):103-115.
2. Finkel RS et al. Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord. 2018;28(3):197-207.