[From gene to diseases; hypokalemic periodic paralysis].

Hypokalaemic periodic paralysis is an autosomal, dominantly inherited disorder, characterised by attacks of partial or total muscle weakness and serum hypokalaemia. the mutations responsible are located in the CACNA1S gene (type 1) and in the SCN4A gene (type 2), and are all missense mutations where arginine is mostly replaced by histidine or sometimes glycine. The mutation has been localised in the voltage sensor of the transmembrane segment of calcium channel (type 1) and sodium channel (type 2) respectively. How muscle weakness develops is not known. Oral or intravenous administration of potassium is helpful in treating partial or complete attacks. Acetazolamide can reduce the frequency of attacks in type-1 hypokalaemic periodic paralysis.