SMN2 and spinal muscular atrophy, type 1: Kaplan–Meier survival plots of patients with SMA type 1 with different SMN2 copies (Figure 4B) showed that the median survival time was 1.58 years in patients with 2 SMN2 copies, undefined in patients with ≥3 SMN2 copies, and 2.08 years in patients with unknown SMN2 copies (p = 0.0160).