Queston #8790Note

Paramyotonia congenita is an autosomal dominant disease that presents with cold-induced myotonia due to a mutation in the gene SCN4A (a voltage gated Na channel) 

sx of paramyotonia congenita also worsens with activity which is considered a paradoxical response


In myotonia congenita sx worsen after a period of rest and may improve with activity; associated with CLCN1 gene mutation