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Spinal Muscular Atrophy (SMA)


About SMA

Spinal muscular atrophy (SMA) is a rare, genetic, neuromuscular disease affecting approximately 1 in 10,000 live births globally, with an estimated incidence in Europe ranging from 1 in 3,900–16,000 live births. 

It is caused by homozygous mutations in survival of motor neuron 1 gene (SMN1) resulting in SMN protein deficiency. Characterised by degeneration of motor neurons, SMA leads to progressive muscle weakness and muscle wasting (atrophy), loss of lung function and difficulty swallowing.  At diagnosis, the broad spectrum of SMA phenotypes are classified into clinical types based on age of onset and maximum motor function ever achieved: type 0 (usually fatal at birth); type 1 (unable to sit independently); type 2 (able to sit independently but not walk); type 3 (independent walking) and type 4 (independent walking and adult onset).  However, variations in disease progression and disease heterogeneity regardless of type have been evidenced by natural history studies; therefore, SMA management recommendations in the rehabilitation phase are based on the current mobility level of patients – that is, whether the patient is a non-sitter, sitter or walker.

Without treatment, and depending on the severity of the condition, life expectancy in the severe forms may be less than two years and the ability to breathe (without respiratory support), swallow, sit and walk may be substantially impaired.  In addition, the lives and independence of individuals with SMA and also their caregivers are heavily impacted.

Living with SMA

People living with SMA usually require the support of multidisciplinary teams, and this is an important factor in why SMA is challenging for healthcare systems to manage. 

The necessary elements to consider in the optimal management of a person living with SMA, as recommended in the guidelines, include comprehensive genetic diagnoses and counselling, regular physical therapy and rehabilitation, orthopaedic care, growth and bone health care, nutritional support, pulmonary care, acute care, management of other organ system involvement, medication and considerations for palliative care. In addition to the necessary multidisciplinary management of patients, innovative pharmacological medicines for SMA are also crucial to improve the health outcomes of SMA patients. In this area there has been significant progress in recent years: Spinraza was the first medicine to treat SMA approved by the European Medicines Agency (EMA), in 2017. In addition, two other treatments have been approved more recently by the EMA: Zolgensma  (2020) and Evrysdi  (2021).

Hopefully, one day we will have access to a new treatment that will change our lives and we will no longer have to go to the hospital to measure my daughter’s lost movements and instead to measure her recovery

SMA patient testimonial