1589 – Prognostic value of the number of copies of the survival of motor neurone 2 (SMN2) gene for the severity of spinal muscular atrophy to determine eligibility for nusinersen in pre-symptomatic patients (Co-dependent)

Referral for advice from the Pharmaceutical Benefits Advisory Committee (PBAC). Medicare Benefits Schedule (MBS) funding is not being sought for this medical service.

Quantitative real-time polymerase chain reaction testing is used to diagnose spinal muscular atrophy (SMA), using samples of dried whole blood obtained from a heel prick. The test assesses homozygous deletion or mutation of the Survival-of-Motor-Neuron 1 (SMN1) gene. If the test is positive for SMA, another test is conducted to determine SMN2 copy number status.

Spinal muscular atrophy in the pre-symptomatic setting is only routinely offered to individuals suspected to be at risk of SMA (e.g. siblings and other relatives of patients diagnosed with SMA).

Type: Co-dependent technology, because access to the medicine is dependent on results of a test.

Spinal muscular atrophy is an autosomal recessive progressive neuromuscular disease caused by mutations or deletions in the SMN1 gene on chromosome 5q. Alterations to this gene result in deficiency of SMN protein, which in turn results in loss of motor function and respiratory failure. Respiratory muscle failure is the major cause of morbidity and mortality for patients with SMA. As SMN2 copy number varies from patient to patient, there is a clinical spectrum of the disease where fewer SMN2 gene copies sometimes correlate to earlier age of onset and increased disease severity, however due to disease modifying factors in some patients, such correlation is not always apparent. The condition begins during the first 3 months of life, and the majority of motor neurons are lost before 6 months of age.

• PASC meeting: -
• ESC meeting: 13 June 2019
• MSAC meeting: 1 to 2 August 2019