In DM1 NSCs, insertion of poly A signals upstream of DMPK CTG repeats by TALEN-mediated homologous recombination significantly eliminated mutant transcripts and nuclear RNA foci, corrected mis-splicing, and ultimately reversed phenotypes (Xia et al., 2015; Gao et al., 2016). The gene discussed is DMPK; the disease is myotonic dystrophy type 1.