Referenced in: none

Automatically associated channels: ClC1 , ClC4 , Nav1.4

Title: Myotonia in DNM2-related centronuclear myopathy.

Authors: Ron Dabby, Menachem Sadeh, Ronit Gilad, Karin Jurkat-Rott, Frank Lehmann-Horn, Esther Leshinsky-Silver

Journal, date & volume: J Neural Transm, 2014 May , 121, 549-53

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/24366529

Abstract
Centronuclear myopathy (CNM) is a rare hereditary myopathy characterized by centrally located muscle fiber nuclei. Mutations in the dynamin 2 (DNM2) gene are estimated to account for about 50 % of CNM cases. Electromyographic recordings in CNM may show myopathic motor unit potentials without spontaneous activity at rest. Myotonic discharges, a distinctive electrical activity caused by membrane hyperexcitability, are characteristic of certain neuromuscular disorders. Such activity has been reported in only one CNM case without a known genetic cause. We sequenced the DNM2 gene and the genes associated with myotonia (CLCN1, SCN4A, DMPK and ZNF9) in a sporadic adult patient with CNM and myotonic discharges. Sequencing the entire coding region and exon-intron boundaries revealed a heterozygous c.1106g-a substitution in exon 8, resulting in a R369Q change in the DNM2. Sequencing the CLCN1, SCN4A, DMPK and ZNF9 genes ruled out mutations in these genes. This is the first report of DNM2-related CNM presenting with myotonia. The diagnosis of CNM should be considered in patients with myotonic discharges of an unknown cause.