_ERN-NMD_
Versione in italiano
WHAT IS IT
Spinal Muscle Atrophy (SMA) is a neuromuscular disorder characterized by a progressive motor neurons degeneration. These neurons are located in the spinal cord and are crucial for muscles strength and movement control. The disease is caused by recessive mutations in the SMN1 gene, resulting in a deficiency of the SMN protein which is fundamental for motor neurons survival. The lack of this protein lead to a progressive motor neuron loss and muscle weakness. SMA is broken into several types, based on how severe the symptoms are and at what age they started. SMA type I (Werdnig-Hoffmann’s disease), is the most common and severe form which usually becomes obvious between birth and 6 months of age. Muscle weakness and respiratory failure are the typical symptoms which occur within the second year of life. SMA type II, is an intermediate type which usually occurs after sixth months of child's life. Most children can sit without help, but they cannot stand or walk and need a wheelchair. Because of progressing muscle weakness, the spine usually curves (scoliosis) over time. SMA type III (Kugelberg-Welander’s disease), usually start after a child's first year and a half of life. Most children can stand or walk without help. But because of progressing muscle weakness, walking and climbing stairs may become difficult over time. SMA severity is related to the residual number of the gene SMN2 (from 0 to more than 4 copies), which is able to produce minimal amount of SMN protein.
HOW DO WE RECOGNIZE IT
The diagnosis is based on the neurological examination aim to find clinical features suggestive of SMA. Electrodiagnostic studies such as electromyography is helpful in reveling motor neuron dysfunction. Genetic analysis is required in order to establish confirmatory diagnosis. The prenatal genetic exam is highly recommended when there is a positive family history for SMA.
HOW DO WE TREAT IT
FDA has approved Nusinersen as the first effective treatment for SMA in 2016. This drug increases the ability of SMN2 genes to make more SMN protein improving clinical symptoms consequently. The treatment efficacy is significantly higher when administered in early disease stage. A second drug with similar mechanism of action is Risdiplam, waiting for final approval in Europe. Furthermore, there are other pharmacological treatments such as Onasemnogene abeparvovec that can replace the impaired SMN1 gene with significant outcome from clinical trials waiting for approval.
WHAT DO WE DO IN OSPEDALE SAN RAFFAELE
Multidisciplinary approach for pediatric and adult forms of SMA, genetic diagnosis and approved therapies.
REFERRING DOCTORS for this deseaseat Ospedale San Raffaele
