SMN2 and proximal spinal muscular atrophy: Similarly, Zhou et al. generated u-iPSCs from spinal muscular atrophy (SMA) patients and converted the survival motor neuron 2 (SMN2) gene to a survival motor neuron 1 (SMN1)-like gene using CRISPR/Cpf1 and single-stranded oligodeoxynucleotides (ssODN).