Session Information
Date: Saturday, October 6, 2018
Session Title: Genetics (Non-PD)
Session Time: 1:45pm-3:15pm
Location: Hall 3FG
Objective: To report the phenotypic and genotypic characteristics of a Taiwanese family with inherited neuromyotonia associated with KCNQ2 mutation.
Background: Neuromyotonia is a disorder of peripheral nerve hyperexcitability (PNH) characterized by muscle cramps, stiffness, myokymia, delayed muscle relaxation after contraction, and hyperhidrosis. Usually cause of neuromyotonia was acquired autoimmune mechanisms against voltage-gated potassium-channel and rare cause was genetic disorders of potassium channels. Mutations are reported mostly in the KCNA1 gene and only one inherited PNH-associated mutation has been described in KCNQ2 (p.Arg207Trp).
Methods: Seven family members (six affected) were available for clinical studies. Myokymia was characterized by video and electromyography. Two patients and one unaffected relative were recruited for exome sequencing. The effect of mutations in KCNQ2 was studied by measurement of potassium current and protein expression using two-microelectrode voltage clamping and western blot, respectively. The informed consent was obtained by the patients. The hospital’s Institutional Review Board Committee approved the study.
Results: We report a family presented with facial and limbs myokymia worsening with febrile illness, spicy food and hot weather with variant clinical features including myasthenia gravis, dystonia-like gait, paroxysmal dyspnea, stiffness, cramps, intermittent facial paresthesia, hyperhidrosis and/or mood disorders but absence of epilepsy or episodic ataxia. Genetic analysis detected a novel KCNQ2 variant (c.409A>T, p.Phe137Ile) in the second transmembrane segment of the protein. Further functional analysis revealed a dominant-negative effect of this KCNQ2 mutation.
Conclusions: We describe a family with an inherited neuromyotonia linked to a novel KCNQ2 (p.Phe137Ile) mutation with variability of phenotype and expands the clinical spectrum of KCNQ2 mutation. The abstract has been presented in the oral poster section at the conference of XXIII WCN Sep. 16-21, 2017, Kyoto, Japan.
To cite this abstract in AMA style:
Y.T. Hsu, W.D. Lin, Y.W. Yang, D.C. Wu, C.H. Tsai. Inherited neuromyotonia associated with a dominant-negative KCNQ2 mutation [abstract]. Mov Disord. 2018; 33 (suppl 2). https://www.mdsabstracts.org/abstract/inherited-neuromyotonia-associated-with-a-dominant-negative-kcnq2-mutation/. Accessed June 15, 2025.« Back to 2018 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/inherited-neuromyotonia-associated-with-a-dominant-negative-kcnq2-mutation/