Referenced in: none

Automatically associated channels: ClC1 , ClC4

Title: Dosage effect of a dominant CLCN1 mutation: a novel syndrome.

Authors: Genevieve Bernard, Chantal Poulin, Jack Puymirat, Damien Sternberg, Michael Shevell

Journal, date & volume: J. Child Neurol., 2008 Feb , 23, 163-6

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/18263754

Abstract
Multiple mutations in the CLCN1 gene coding for the voltage-gated chloride channel have been documented to cause myotonia congenita. We report a kindred featuring an index patient who possesses 2 copies of a dominantly inherited mutated CLCN1 allele with a resulting novel phenotypic presentation. The index patient is a boy who presented initially for evaluation at the age of 5 years with a 2-year history of gait problems. Both parents and 3 male siblings were entirely well. Examination revealed a striking diffuse muscular hypertrophy, diffuse mild to moderate weakness, Gower sign, percussion, and grip myotonia. Electromyography confirmed myotonia, and molecular analysis revealed 2 copies of the T310M mutation on the CLCN1 gene. Testing of family members revealed a normal neurological examination without clinical myotonia in all and electromyographic evidence of myotonia and a single copy of the T310M mutation in both parents and 2 siblings. Our kindred is the initial demonstration of the dosage effect of a dominant mutated allele in the CLCN1 gene.