SCN4A and Myotonia: More individuals with non-dystrophic myotonias were currently taking at least one medication for myotonia with 51.9% (n =14) of individuals with CLCN1 variants and 80.0% (n = 12) of individuals with SCN4A variants compared to 13.5% (n = 12) of individuals with DMPK expansions, and 18.2% (n = 2) of individuals with CNBP expansions.