Changes in SMN mRNA and protein levels observed in SMA patient-derived PBMCs mirror those observed in SMA cell lines (Sumner et al., 2006; Simard et al., 2007; Vezain et al., 2007; Tiziano et al., 2010; Crawford et al., 2012). The gene discussed is SMN2; the disease is proximal spinal muscular atrophy.