SMN2 and spinal muscular atrophy, type 1: The SMA cohort at T4 included seven females and six males under therapy including five patients with SMA type I (SMN copy number of two patients = 3 and three patients = 2), seven patients with SMA type II (SMN copy number of five patients = 3 and two patients = 4), and one patient with SMA type III (SMN copy number = 6) (Fig. 1).