SMN1 and proximal spinal muscular atrophy: The recent approval of the drug nusinersen (Spinraza) [9,32] represents a considerable advancement in SMA treatment, as it addresses the underlying genetic cause of the disease by modifying the splicing of the SMN2 gene, thereby increasing the production of the functional SMN protein [10,11,12], leading to improved motor and respiratory outcomes [32,33,34,35].