SMN2 and proximal spinal muscular atrophy: Nonetheless, there remain several critical unmet needs related to specific patient populations including but not limited to: (1) newborns with SMA who are not identified by NBS because they have a point mutation rather than a homozygous deletion that is detectable by polymerase chain reaction, (2) patients with two copies of SMN2 and early symptomatic manifestations of SMA, (3) patients with SMA who were born before the implementation of NBS for this disease and (4) patients with SMA who continue to have functional impairments and reduced quality of life.