Atypical periodic paralysis and myalgia

Abstract

<i>RYR1</i> mutations can cause late-onset atypical PP both with and without associated myopathy. Myalgia and cramps are prominent features. The McManis test may be a useful diagnostic tool to indicate <i>RYR1</i>-associated PP. We propose that clinicopathologic features suggestive of <i>RYR1</i>-related disorders should be sought in genetically undefined PP cases and that <i>RYR1</i> gene testing be considered in those in whom mutations in <i>SCN4A, CACNA1S</i>, and <i>KCNJ2</i> have already been excluded.