SMA Screening

Newborn screening followed by an early diagnosis of SMA allows for pre-symptomatic treatment, significantly enhancing the effectiveness of therapies.

This proactive approach greatly increases the likelihood that a child will develop without disabilities. In contrast, diagnosing SMA based on symptoms often leads to lifelong physical disability.

Spinal Muscular Atrophy

Spinal Muscular Atrophy, or SMA, is a genetic neuromuscular condition where patients gradually lose muscle strength, affecting the patient’s ability to, for example, sit up, walk and, in severe cases, the ability to breath and swallow.

Causes

The disease is inherited in an autosomal recessive manner and is caused by genetic variants in the Survival Motor Neuron 1 (SMN1) gene, leading to very low levels of the SMN protein which is crucial for functional motor neurons. In 95% of SMA patients the disease is caused by a homozygous deletion of exon 7 of SMN1.

Markers for SMA

Early detection of SMA through newborn screening is based on qualitative detection of homozygous deletion of exon 7 of the Survival Motor Neuron 1 (SMN1) gene. This deletion, present in approximately 95% of SMA patients, serves as an efficient marker for early disease detection.

Types of SMA

There are four types of SMA, Type I – Type IV, with different levels of severity and age of onset. The severity is associated with the number of copies of the homologous SMN2 gene which can serve as a ‘backup’ gene. In its most severe form, Type I, also referred to as infantile onset SMA or Werdnig-Hoffmann disease, infants show symptoms within six months from birth, and the life expectancy without pharmaceutical treatment is less than 2 years.

SMA Prevalence

SMA is a leading genetic cause of infant mortality, with prevalence estimates of 1 in 6,000 to 1 in 10,000 live births and a carrier frequency as high as 1 in 54.

Treatment

Until recently, SMA patients could receive symptomatic treatment but there was no effective treatment for the underlaying cause of the disease. However, since 2016, innovative pharmaceuticals and gene therapies enabling the patient to produce functional SMN protein has been approved. These new treatments have led to a high demand for including SMA on recommended newborn screening panels in several countries.

Newborn screening for SMAcan detect the genetic variant in the SMN1 gene before symptoms appear and allow for the earliest possible treatment with the opportunity to delay motor neuron degeneration.

Benefits

That come with an early detection of SMA

Timely treatment for SMA

Early detection allows for the prompt initiation of disease-modifying therapies, which play a critical role in preserving existing neurons and preventing further degradation.

Additionally, treatments are often more effective when administered before symptoms appear.

Reduced complications

The progression of muscle weakness and respiratory issues can be slowed, preventing severe disability. This proactive approach minimizes the frequency and severity of hospitalizations.

Comprehensive screening

Newborn screening from a single blood spot identifies multiple genetic and metabolic disorders, ensuring early detection and timely intervention for better health outcomes.