Type 0 SMA is the most severe form of SMA. It is characterized by the appearance of prenatal symptoms such as reduced movement of the foetus. At birth, severe clinical signs (hypotonia, weakness, retractions, difficulty feeding, respiratory failure, etc.) complete the clinical features. Given the severity of this form of SMA, should these infants be treated? Only two studies have been published so far on the subject, showing moderate efficacy of the treatment (with Spinraza® in one case and with Spinraza® combined with Zolgensma® in the other).
An Italian team reported in November 2020 the story of a couple whose first child, with type 0 SMA, died at the age of 23 days without disease-modifying treatment. For their second child, also suffering from type 0 SMA (with a single copy of the SMN2 gene), the question of setting up a disease-modifying treatment quickly arose. The family was informed of the lack of data on the subject and the decision to initiate treatment was made after consultation with an ethics committee. Treatment with Spinraza® (nusinersen) was started at the age of 13 days. After two months (after the third dose of treatment), the infant’s motor skills improved moderately. The slight improvement in respiratory function did not prevent placement of a tracheostomy at the age of 4 months. Following repeated infections and deterioration of heart function, the infant died of cardiac arrest at the age of 5 months. Families and clinicians now have three studies on the relative effectiveness of Spinraza® in type 0 SMA, which will help them make a decision about whether to set up a background treatment for this very severe form of SMA.
