SCN4A-associated hypokalemic periodic paralysis merits a trial of acetazolamide

Abstract

Primary hypokalemic periodic paralysis (HypoPP) is characterized by episodes of transient flaccid paralysis in association with reduced serum potassium levels.1 Onset of transient weakness is typically in the first or second decade, often on awakening. Weakness may be mild and focal or progress to flaccid quadriplegia, and the duration may last hours to days. Interindividual attack frequency varies, from daily episodes to a single lifetime episode, commonly decreasing with age. Predictable triggers are rest after exercise and high carbohydrate meals. Unlike hyperkalemic periodic paralysis, myotonia is absent. A proportion of affected individuals have slowly progressive permanent weakness. Inheritance is autosomal dominant, although one-third of cases are sporadic, and penetrance is reduced in women. HypoPP is genetically heterogeneous. Three common mutations in CACN1AS , the α-subunit of the skeletal …