In addition, defects in the genes involved in dysfunctional neurite outgrowth and synaptogenesis at the neuromuscular junction were also observed in neuronal progeny derived from DM1 mutant human ES cells, which are associated with the decreased expression of two genes that belong to the SLITRK family, SLITRK2 and SLITRK4 (Marteyn et al., 2011). Here, SLITRK4 is linked to myotonic dystrophy type 1.