A careful review of previous studies on SMA screening using DBSs revealed that a frequently used technique to detect SMN1 deletion involves real-time PCR technology with a fluorescent hybridizing probe; the fluorescent probe binds to an SMN1-specific sequence [28,29] or to a common sequence between SMN1 and SMN2 [30]. This evidence concerns the gene SMN2 and proximal spinal muscular atrophy.