Referenced in: none

Automatically associated channels: ClC1 , ClC4

Title: A novel N440K sodium channel mutation causes myotonia with exercise-induced weakness--exclusion of CLCN1 exon deletion/duplication by MLPA.

Authors: F Lehmann-Horn, M Orth, M Kühn, K Jurkat-Rott

Journal, date & volume: Acta Myol, 2011 Oct , 30, 133-7

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/22106717

Abstract
We report a 4-generation Turkish family with 10 affected members presenting with myotonia and potassium- and exercise-induced paralytic attacks. The clinical presentation was neither typical for the chloride channel myotonias Thomsen and Becker nor for the separate sodium channel myotonia entities potassium-aggravated myotonia, paramyotonia congenita, and hyperkalemic periodic paralysis. It is best described by a combination of potassium-aggravated myotonia and hyperkalemic periodic paralysis. We excluded exonic chloride channel mutations including CLCN1 exon deletion/duplication by MLPA. Instead we identified a novel p.N440K sodium channel mutation that is located at the inner end of segment S6 of repeat I. We discuss the genotype phenotype relation.