ABSTRACT
Familial hypokalemic periodic paralysis (HOPP) is an autosomal dominant disorder characterized by episodic attacks of muscle weakness with concomitant hypokalemia (<3.5 mEq/L). The onset of HOPP usually occurs within the first and second decade of life. Mutations in the skeletal muscle calcium (CACNL1A3) and sodium channel (SCN4A) genes have been reported to be responsible for familial HOPP. Voltage-sensitive ion channels mediate action potentials in electrically excitable cells and play important roles in signal transduction in other cell types. Therefore, abnormalities in a channel's function lead to disarray of signal transduction and thus various neurological symptoms. Those are called channel diseases, which include familial HOPP. We report a 14-year-old boy with HOPP from a family in which two members of two generations are affected. Genetic examination identified a mutation causing a codon change from arginine to histidine at the amino acid portion #528 (R528H) in the calcium channel gene CACNL1A3.