SMN1 and proximal spinal muscular atrophy: It is approved to treat patients with SMA in >40 countries worldwide, and is authorized in patients with 5q SMA with a bi-allelic mutation in the SMN1 gene and a clinical diagnosis of SMA type 1, or up to 3 copies of the SMN2 gene in the European Union [8], and in pediatric SMA patients aged <2 years with bi-allelic mutations in the SMN1 gene in the United States [9].