SMN1 and proximal spinal muscular atrophy: The population of 18 SMA patients consisted of 10 females (56%) and 8 males (44%), comprising 4 children (22%) with infantile‐onset SMA (2 SMN2 copies, most likely classified as SMA I) with a median age of 2.8 months (age range: 18 days–11.1 months) and 14 children (78%) with later‐onset SMA (>2 SMN2 copies, most likely classified as SMA II–III) with a median age of 8.4 years (age range: 1.1–17.2 years; Table 1).