Research Article Open Access Introduction Nondystrophic myotonias (NDM) and myotonic dystrophies (DM) affect muscle ion-channel isoforms, leading to muscle membrane hyperexcitability.1-3 NDM symptoms typically emerge in childhood and may be subtle but persistent, with myotonia followed by hypertrophy, muscle weakness, and fatigue as children develop.4-6 Chloride channelopathies caused by CLCN-1 mutations are the autosomal dominant condition Thomsen myotonia congenita (MC), and the autosomal...