DMPK and myotonic dystrophy type 1: The absence of severe fixed weakness or muscle wasting distinguishes NDMs from dystrophic myotonias, such as myotonic dystrophies type 1 and type 2 (DM1 and DM2 due to DMPK and CNBP mutations, respectively), which present with both progressive muscle weakness and multisystem involvement (Figure 4) (87).