SMN1 and proximal spinal muscular atrophy: Figure 4 shows that the quantitation cycle values (Cq values) of 50 SMA patients with SMN1(–) were markedly higher than those of 50 controls with SMN1(+), without overlapping values. The mean ± SD Cq values of SMA patients and controls were 19.0 ± 1.4 and 10.1 ± 1.2, respectively. In the present study, we determined that Cq values ≥14 indicated the absence of SMN1.