Spinal muscular atrophy - clinical spectrum and therapy

Spinal muscular atrophy (SMA) is a progressive autosomal recessive motor neuron disease with an incidence of 1:10,000 live births, caused by loss of the survival motor neuron 1 gene (SMN1), and represents the most frequent neurodegenerative disorder in children. With greater understanding of the molecular basis of SMA in the past two decades, a major focus of therapeutic developments has been on increasing the full-length SMN protein by increasing the inclusion of exon 7 in SMN2 transcripts, enhancing SMN2 gene expression, stabilizing the SMN protein or replacing the SMN1 gene. Although the SMA research field is rapidly expanding with new therapeutic opportunities, there are still several issues that remain unsolved. The timing of an optimal intervention is not clear, in particular the point at which there is irreversible pathology precluding any meaningful therapeutic response. Early diagnosis will be crucial for therapeutic success; presumably, the clinical outcome will be much better if treatment already starts presymptomatically. Therefore, presymplomatic diagnosis of SMA via a nationwide genetic newborn screening will be key for an efficient therapy prior to motor neuron death.