For babies with SMA fast diagnosis is vital. This is because any lower motor neuron damage occurring before treatment is irreversible4,5
SMA is a rare, progressive, inherited monogenic disease, characterized by lower motor neuron degeneration and muscle weakness6–10
Untreated, SMA is the 2nd most common fatal autosomal recessive disorder after cystic fibrosis11
SMA remains the leading genetic cause of infant mortality in the absence of therapeutic intervention5,10
SMA is typically classified into 4 phenotypes (Types 1–4) that range in severity. SMA Types 1 and 2 are the most severe and common forms with onset between birth and 18 months3,5,10
SMA affects approximately 1 in 10,000 – 12,000 live births and can impact any race or sex6,12
More than 1 in 58 people are carriers of the disease mutation13
SMA is caused by an absent or dysfunctional survival motor neuron 1 (SMN1) gene14–18
The body has a back-up gene, SMN2, however, it is only capable of producing a small amount of functional SMN protein, which is insufficient for motor neuron survival and function6,14,15,17,18
Click to see the difference:
SMN protein is critical for neuronal survival and neuromuscular junction formation15
SMN1 is the primary gene that encodes SMN protein with SMN2 as a back-up15,19
Functional SMN protein
Non-functional SMN protein
Functional SMN protein
Non-functional SMN protein
SMN1 gene is absent or dysfunctional14–17
SMN2 alone is unable to produce sufficient SMN protein6,14,15,18
SMN protein deficiency leads to irreversible neuronal degeneration and loss of muscle function in SMA5,14,15
Functional SMN protein
Non-functional SMN protein
Functional SMN protein
Non-functional SMN protein
Loss of motor neurons in SMA is irreversible4,5
More than 90% of untreated patients with SMA Type 1 will not survive or will need permanent ventilatory support by 2 years of age20
Every delay in the diagnosis of SMA Type 1 can jeopardize lower motor neuron survival,4 directly impacting neuromuscular function21
Your rapid referral is crucial to halt or delay disease progression, and enable your patient access to the best available care4,10,22
PNCR: SMA Type 1 survival rates*
NeuroNext: SMA Type 1 survival rates*
PNCR, Pediatric Neuromuscular Clinical Research
*Event-free survival for PNCR = no death, and no need for ≥16 hours/day ventilation continuously for 14 days, in the absence of an acute reversible illness;20 n=23 (Type 1 patients with 2 copies of SMN2). Survival for NeuroNext = no death, or no intubation; n=2021
Adapted from Anderton RS and Mastaglia FL. 201515, Finkel RS. 201324, Finkel RS, et al. 201420 and Kolb SJ, et al. 201721
While patients diagnosed with SMA Type 2 (with disease onset between 6–18 months of age) may possibly reach motor milestones in the first years of life, all patients will show a clear and progressive decline with long-term follow-up8
Every delay in the diagnosis of SMA can jeopardize lower motor neuron survival,4 directly impacting neuromuscular function4,10,22
Your rapid referral is crucial to halt or delay disease progression, and enable your patient access to the best available care4,10,22
TIMPSI: Average Test of Infant Motor Performance Screening Items
Adapted from Kolb SJ, et al. 201721
References
NMD, Neuromuscular disease.
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