Sodium channel myotonia (SCM) and paramyotonia congenita (PMC) are rare non-dystrophic muscle disorders with muscle hyperexcitability caused by gain-of-function mutations in the voltage-gated skeletal muscle sodium channel gene (SCN4A) (Stunnenberg et al., 2020). This evidence concerns the gene SCN4A and paramyotonia congenita of Von Eulenburg.