SMN1 and proximal spinal muscular atrophy: Multiplex ligation probe-dependent amplification (MLPA) was performed using SALSA MLPA Probemix P060-B2 SMA carrier (MRC, Holland) to rule out type 0 spinal muscular atrophy in S2, which revealed a normal copy number of exons 7 and 8 of the SMN1 gene.