Potassium-aggravated myotonia (PAM) is a muscular channelopathy presenting with a pure myotonia dramatically aggravated by potassium ingestion, with variable cold sensitivity and no episodic weakness. This group includes three forms: myotonia fluctuans, myotonia permanens, and acetazolamide-responsive myotonia. The disease is potassium-aggravated myotonia (Monarch Disease Ontology entry MONDO_0018959). Also known as: K+-aggravated myotonia, K-aggravated myotonia, PAM, Potassium aggravated myotonia, myotonia congenita, atypical, acetazolamide-responsive.