CACNA1S and hypokalemic periodic paralysis: Heterozygous, dominant-acting CACNA1S mutations have previously been associated with susceptibility malignant hyperthermia triggered by volatile anesthetics (MHS5; MIM#601887) [11,12], hypokalemic periodic paralysis (HOKPP; MIM#170400), which is characterized by acute flaccid weakness episodes associated with low serum potassium levels (<2.5 mEq/L) and, occasionally, the development of permanent muscle weakness after several years of continuous episodes [13,14], and thyrotoxic periodic paralysis (TTPP1; MIM#188580) [15].