SMA
TYPE 1
Spinal Muscular Atrophy (SMA) is the collective name for a group of neuromuscular disorders that lead to the malfunctioning of muscles.
WHAT IS
SMA?
Spinal Muscular Atrophy (SMA) is the collective name for a group of neuromuscular disorders that lead to the malfunctioning of muscles. Most neuromuscular disorders, like SMA, are relatively rare. The disorders called SMA have in common that there is something wrong with the motor nerve cells in the spinal cord that stimulate the muscles. A number of these cells do not function so that no or inadequate signals are transmitted to the muscles, resulting in weakening or paralysis of the muscles.
SMA can be classified based on the age at diagnosis in types 1, 2, 3 and 4
SMA TYPE 1
SMA TYPE 2
SMA TYPE 3
Werdnig-Hoffmann disease
Diagnosis at 0-6 months of age
Wohlfart-Kugelberg-Welander disease
Diagnosis at 1,5 - 18 years old
Intermediate type
Diagnosis at 6-18 months of age
SMA TYPE 4
Adult type
Diagnosis at over 18 years old
WHAT CAUSES
SMA?
SMA is caused by a deficient gene, called survival motor neuron 1, SMN1. This gene is responsible for producing the SMN protein and helps to keep motor neurons healthy. In SMA the SMN1 gene is missing or mutated, so that less SMN protein is produced, causing the neurons to die and consequently the muscles start to weaken.
The body provides a kind of backup system, SMN2, like a spare copy of the SMN1 gene. This SMN2 is functional in SMA patients and produces the SMN protein. However, it is a shortened version of it, which means it still cannot do its job properly.
MEDICAL
TREATMENT.
SPINRAZA®
Spinraza® (Biogen) is the first, and currently only, approved (by the EMA-European Medicines Agency) treatment for patients with SMA. Since September 1, 2018, the medicine Spinraza® is reimbursed in Belgium for patients with the rare SMA muscle disorder.
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Spinraza® is administered by means of a spinal cord injection and acts on the SMN2 gene. It gives the gene a boost, so that it starts producing more protein and the neurons are protected again. That halts the evolution of the disease.
ZOLGENSMA®
The pharmaceutical company Avexis (part of Novartis) applied for approval in Europe and America for Zolgensma® (AVXS-101) on October 18, 2018 as a medicine for babies with SMA type 1. On May 24, 2019 the medicine was approved in America for babies with SMA under two years of age. The decision of the EEA on approval in Europe is expected within a few months. Zolgensma® is a gene therapy and the patient is given a functional copy of the damaged gene. It involves a single intravenous injection.
RISDIPLAM®
Risdiplam® is a medicine for SMA that is being developed by the pharmaceutical company Roche, in collaboration with PTC Therapeutics and the SMA Foundation. On November 25, 2019, Roche announced that it had applied for approval in America. Just like Spinraza®, Risdiplam® acts on the SMN2 gene, by means of a syrup instead of a spinal cord injection.