Spinal muscular atrophy (SMA) is a group of genetic neuromuscular conditions that affect lower motor neurons in the spinal cord.¹ Motor neurons are nerve cells that transmit signals from the brain to the spinal cord, which controls the movement of muscles. In SMA, the motor neurons do not work properly and can affect muscles that control voluntary movement such as in the arms, legs and head, as well as muscles involved in speech, swallowing and breathing.² If left untreated, symptoms such as muscle weakness can worsen over time (progressive) and cause muscle wasting (atrophy).¹

The most common form of SMA is SMN1-related SMA, which is caused by deficiency of SMN protein due to disease-causing genetic variants in the SMN1 gene.^2,3 The survival motor neuron (SMN) protein is important for motor neuron function and maintenance. There is a second gene, SMN2, which can affect the severity of the condition.⁴ Please note that information on this page is focussed on SMN1-related SMA; where it refers to SMA below it is specific to SMN1-related SMA. There are rarer types of SMA, such as X-linked SMA, SMA with lower extremity dominance (SMA-LED) and SMA with respiratory distress (SMARD1) and others, which are caused by defects in other genes – these are not covered on this page. Please refer to the other specific conditions for information on those other types of SMA.^1,3

SMA can vary in onset and severity of symptoms. SMA can affect the ability to achieve motor milestones such as sitting, standing and walking, depending on the severity of the condition.^2-5 If left untreated, it leads to progressive decline in motor function, which may eventually affect feeding and breathing, and reduced life expectancy in severe cases, with most having a life expectancy of less than 2 years. With treatment, individuals with SMA are able to achieve motor milestones that they would not have otherwise reached and are able to live longer than individuals previously have without treatment.^6-11 Those who are diagnosed and treated before developing symptoms have the greatest increase in motor function.

Synonyms of SMN1-related SMA: Proximal spinal muscular atrophy; 5q spinal muscular atrophy  

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

ORPHA:70 Proximal spinal muscular atrophy 

ICD-11: 8B61 Spinal muscular atrophy 

Historically, before treatment was available, SMA was classified into different types based on age of onset of muscle weakness and maximal motor milestones attained. This ranged from fetal (Type 0; most severe), to before 7 months (Type 1, non-sitter), between 7 and 18 months (Type 2, sitter), after 18 months (Type 3, walker) and during adulthood (Type 4, mildest). With early diagnosis and treatment of SMA, the historical classification of SMA type is no longer applicable. A functional classification (non-sitters, sitters, standers and walkers) is now utilised and SMN2 copy number (more information on SMN2 is provided in the Cause and Inheritance section) is used to predict disease severity. 

Symptoms of SMA can vary widely between individuals, ranging from mild to severe. If SMA is not diagnosed early and treated, it can cause the following:^2-5

• muscle weakness and/or low muscle tone (hypotonia) in the shoulders, arms, legs, torso, and/or hips – children may seem ‘floppy’ 
• poor head control 
• difficulty breathing, swallowing, sucking or feeding 
• weak cry or cough 
• unable to sit or roll independently 
• able to sit but not walk independently; for those who achieve this milestone they may lose this ability over time 
• scoliosis (curvature of the spine) 
• tremors or twitching 
• reduced life expectancy, with a life expectancy of below 2 years in severe cases 

Early diagnosis and treatment can prevent some of these symptoms from developing, enable children with SMA to gain motor skills, achieve motor milestones and have an improved life expectancy.^6-11

Please speak to your medical team to learn more about the symptoms and complications of this condition. 

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

SMA is a genetic condition. SMN1-related SMA is caused by disease-causing genetic changes (variants) in the SMN1 gene on Chromosome 5.¹² The SMN1 gene is responsible for producing a protein called survival motor neuron (SMN), which is important for motor neuron function and maintenance.  

All individuals have two copies (alleles) of the SMN1 gene – one on each chromosome that is inherited from each parent. SMA is an autosomal recessive condition, which means both copies of the SMN1 gene must have the disease-causing genetic variants. Majority individuals with SMA have an exon 7 deletion in both copies of their SMN1 gene. 

Individuals with the genetic variant in only one copy are unaffected but will be a carrier and may pass on that variant to their children. If both parents are carriers (each have a copy of the disease-causing variant), there is a 25% chance the child will inherit both disease-causing variants and have SMA.  More information on autosomal recessive inheritance pattern can be found at Centre for Genetics Education: Autosomal recessive inheritance. 

All individuals also have a SMN2 gene, which can also produce a small amount of functional SMN protein.^3,4 The amount of SMN protein produced by the SMN2 gene is not enough to fully compensate for (make up for) the loss of SMN1 gene in SMA but it can affect severity of disease. Individuals with more copies of SMN2 (higher copy number) tend to have less severe forms of SMN1-related SMA. For individuals diagnosed with SMA before symptoms are present (typically by newborn screening), the SMN2 copy number is the best indicator of severity – individuals with a higher copy number are predicted to have milder disease severity.  

Carrier screening  

Genetic carrier screening, also known as reproductive carrier screening (RCS), for SMA can identify a reproductive couple’s risk (high or low) of having a child with SMA.¹³ It is covered by Medicare for any Medicare eligible individuals who is pregnant or planning pregnancy, even in the absence of family history of SMA.¹⁴

More information about carrier screening for SMA can be found at:

• Australian Government Department of Health and Aged Care: Reproductive carrier testing for cystic fibrosis, spinal muscular atrophy and fragile X syndrome (Last updated 22 November 2023)  
• Centre for Genetics Education: Reproductive carrier screening 

If you would like to learn more about the inheritance and impact of this condition, please ask your doctor for a referral to a genetic counsellor. Genetic counsellors are qualified allied health professionals who can provide information and support regarding genetic conditions and testing. More information about genetic counselling can be found at: 

• Information on Genetic Services 
• The National and State Services pages underneath the ‘Genetic Counselling’ sections listed 

Screening 

Newborn screening 

In Australia, SMN1-related SMA is usually detected via the newborn bloodspot screening (NBS) programs.  Shortly after birth and with parental consent, a nurse or midwife will collect the baby’s blood via a heel prick blood test. The healthcare provider will then send it to a specific laboratory to test for a range of rare conditions, including SMN1-related SMA. If the results of these tests suggest that the baby is at risk of having one of these conditions, laboratory staff will quickly get in touch with healthcare providers. The healthcare providers will then arrange for the baby to have further testing that will confirm whether the baby does indeed have the condition. The healthcare providers will also organise for the baby to receive urgent care if required. Depending on your state or territory, parents may or may not receive a notification if the test results are clear. You can find out more about NBS in your state or territory at Australian Government Department of Health, Disability and Ageing: Delivering newborn bloodspot screening programs. 

Newborn bloodspot screening is a reliable way to check for certain rare conditions early in life. Although it’s extremely rare, cases can sometimes be missed. If you are concerned your baby may have a condition that they have already been screened for, you should contact a medical professional.  

Screening for SMN1-related SMA was implemented in Australia’s newborn bloodspot screening (NBS) programs between 2022 – 2024 depending on the state and territory. Babies that were born prior to that may not have been screened for SMA.  

Diagnosis 

A diagnosis of SMA may be suspected based on an abnormal result from NBS but additional tests and a clinical examination will be required to confirm a diagnosis. For individuals who are not screened at birth, SMA is often diagnosed after symptoms develop. 

Diagnosis of SMN1-related SMA is typically made based on clinical examination, electromyography (EMG) to assess muscle and nerve function, and confirmed by genetic testing for SMN1. SMN2 copy number analyses is also performed as SMN2 copy number can influence the severity of the disease and may be used to inform treatment strategies.^15,16

Doctors may perform additional examinations or tests to rule out other conditions that have similar symptoms, such as other hereditary motor neuron conditions, juvenile amyotrophic lateral sclerosis, congenital muscular dystrophies, congenital myopathies, congenital myasthenic syndromes, and myasthenia gravis.⁴

Please speak to your medical team to learn more about the available pathways for diagnosis of this condition. 

There is no curative treatment for SMA. Treatment of SMA is targeted at slowing or stopping progression of SMA, managing symptoms (symptomatic management) and improving quality of life, which involves a multidisciplinary care team.³ Early intervention can improve outcomes of individuals with SMA.^3,6-10

In Australia, there are currently three disease-modifying therapies (DMTs) for SMA that can slow progression of disease, improve motor function and outcomes, including improved life expectancy. These therapies are available for eligible individuals with SMA in Australia through the Pharmaceutical Benefits Scheme (PBS). More information about eligibility requirements for these therapies can be found at https://www.servicesaustralia.gov.au/spinal-muscular-atrophy.

Symptomatic management of SMA may include physiotherapy, occupational therapy, respiratory support (if breathing is affected), speech therapy, use of gastrotomy tube to allow provision of nutrition directly to the stomach, orthotics, and scoliosis surgery.^3,4

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities.

Healthcare professionals involved in the care of individuals with SMA may include general practitioners (GP), paediatricians, geneticists, genetic counsellors, neurologists, respiratory physicians, clinical nurse specialists, physiotherapists, occupational therapists, speech therapists, dietitians, orthopaedic surgeons, and others. The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here.

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

For many rare diseases, palliative care services may be relevant and useful. Palliative care services are available for people (adults, children and their families) living with a life-limiting illness and is not only for end-of-life care. It can also help at any stage of illness from diagnosis onwards, and will look different for different people. Palliative care services provide assistance, support, resources and tools to help people manage their illness and the symptoms, ease pain, and improve comfort and quality of life. If this is relevant to you and you wish to find out more information about palliative care and how it can help you, please visit:

• Australian Institute of Health and Welfare: Palliative care Overview
• Australian Government Department of Health, Disability and Ageing: Palliative care
• Palliative Care Australia

A guideline for newborn screening in spinal muscular atrophy in Australia and Aotearoa New Zealand was developed to provide a child and family focussed approach to newborn screening for SMA across Australia and Aotearoa New Zealand and published in 2025. Recommendations were developed using systematic evidence synthesis in combination with expertise and evidence from an Australian and Aotearoa New Zealand multidisciplinary national committee, with state and territory representation across (newborn) screening, diagnostics, clinical care, advocacy and lived experiences from consumer domains. This Guideline explains to healthcare practitioners involved in (newborn) screening, diagnostics and clinical care of newborns and infants with SMA, how to practice in ways that are accurate, timely and helpful to individuals with the condition and their families.¹⁵

The following guidance is available from international experts outside Australia; however, there may be information that is not relevant or applicable to the Australian context, and may not be up to date:

A consensus statement on SMA standard of care (diagnosis and management) was published in 2007 by a committee of SMA experts that previously established through a 2004 international conference. In 2018, a two-part update to the recommendations was published:

• Diagnosis and management of spinal muscular atrophy: Part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care
• Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

In addition, individuals, their parents, families and carers often develop extensive expertise on their specific rare disease. It is important to recognise that they can contribute valuable knowledge about their rare condition. Rare diseases often impact individuals differently, so it’s important to consider a person’s lived experience.

The Australian Neuromuscular Disease Registry is an Australian-wide registry that collects information about individuals with certain neuromuscular conditions, including SMA. The registry collects important medical information from adult and child patients across the country to improve the understanding of neuromuscular disease and accelerate the development of new therapies.

There are specific considerations around participating in rare disease research, including clinical trials. It is important to be mindful of issues such as data privacy, research ethics, consent and differences in research regulations between Australia and other countries. For more information, please visit the RARE Portal’s Considerations for Participating in Health and Medical Research page.

If you are interested in finding clinical trials for your condition, please visit the following websites; however, there may not be any clinical trials available:

• Australian Clinical Trials
• ClinicalTrials.gov

It is best to discuss your interest in research, including clinical trials,  with your medical team to determine suitability and eligibility.

Australian Organisations:
Spinal Muscular Atrophy Association of Australia
Website: https://www.smaaustralia.org.au/
SMA Australia is the peak consumer body for people living with SMA, supporting families for over 20 years since its foundation in August 2005, evolving from one-on-one family support to national advocates for access to the latest SMA treatments.

Muscular Dystrophy NSW
Website: https://mdnsw.org.au/
Muscular Dystrophy NSW is a NSW-based organisation that supports people living with neuromuscular conditions and their families through information, connection and advocacy. They have an online group called SMArties that allows people living with SMA to connect socially and build friendships with others.

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

SMA varies between individuals, and each person’s experience is unique.

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

SMA Australia: Resources lists support resources that are relevant to people with SMA.

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Further information on SMA can be found at:

• Healthdirect: Spinal muscular atrophy (SMA)
• Centre for Genetics Education: Spinal muscular atrophy
• Genetic and Rare Diseases (GARD) Information Center: Spinal muscular atrophy
• National Organization for Rare Disorders (NORD): Spinal Muscular Atrophy

UNSW Sydney School of Clinical Medicine: NBS for SMA – Guidelines for Australia and New Zealand

Australian Neuromuscular Disease Registry (ANMDR)

GeneReviews®: Spinal Muscular Atrophy

Orphanet: Proximal spinal muscular atrophy

This page has been co-developed by Rare Voices Australia (RVA)’s RARE Portal team in consultation with Spinal Muscular Atrophy Association of Australia and Professor Michelle Farrar, Professor of Paediatric Neurology at UNSW Sydney and specialist child neurologist at Sydney Children’s Hospital, and who was a lead clinician on the SMA NBS pilot program across NSW and the ACT.

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.