CAMKK2 and myotonic dystrophy type 1: In accordance with the splicing shift towards the CAMKK2 variant lacking exon 16, we observed a significantly lower degree of axon branching in DM1-MNs lines #1 and #2 than in Ctrl-MNs lines #1 and #2 (P = 4.92 × 10−9; Fig. 6D and E and Supplementary Fig. 9).