Following this, if the results from MLPA, qPCR, or ddPCR methods return as negative in a patient with clinical and electrodiagnostic findings consistent with SMA, it is recommended to perform full gene analysis of SMN1. One percent of SMA patients have a loss of function SMN1 missense variant (McAndrew et al., 1997; Wirth, 2000). Here, SMN1 is linked to proximal spinal muscular atrophy.