obsolete non-dystrophic myopathy https://github.com/monarch-initiative/mondo/issues/5045 https://www.malacards.org/card/non_dystrophic_myopathy true SCTID:424795008 NANDO:1200496 Orphanet:206656 Reason: grouping class. Term to consider: none OBSOLETE. A group of rare skeletal muscle ion-channel disorders caused by genetic mutations in the sodium and chloride channel genes. It is characterized by altered membrane excitability resulting in skeletal muscle stiffness. This group of myotonias is distinct from myotonic dystrophy because of the absence of systemic features or progressive weakness. non dystrophic myotonia MONDO:0016110 non-dystrophic myotonia NCIT:C122787