Mutations within CLCN1, the gene encoding the major skeletal muscle chloride channel, cause either dominant Thomsen disease or recessive Becker-type myotonia, which are sometimes difficult to discriminate, because of reduced penetrance or lower clinical expressivity in females. We screened DNA of six unrelated Becker patients and found four novel CLCN1 mutations (Gln-74-Stop, Tyr-150-Cys, Tyr-2...

BACKGROUND Myotonia congenita (MC), whether inherited in autosomal dominant or recessive form, is caused by mutation of CLCN1 on chromosome 7 and associated with impaired skeletal muscle relaxation after contraction. The basic pathophysiology is the reduction of chloride conductance in skeletal muscles caused by various molecular mechanisms. The cause of the wide phenotypic variability in both ...

The muscle Cl- channel, ClC-1, is a member of the ClC family of voltage-gated Cl- channels. Mutations in CLCN1, the gene encoding this channel, cause two forms of inherited human muscle disorders: recessive generalized myotonia congenita (Becker) and dominant myotonia (Thomsen). The functional characterization of these naturally occurring mutations not only allowed a better understanding of the...

The voltage-dependent ClC-1 chloride channel belongs to the CLC channel/transporter family. It is a homodimer comprising two individual pores which can operate independently or simultaneously according to two gating modes, the fast and the slow gate of the channel. ClC-1 is preferentially expressed in the skeletal muscle fibers where the presence of an efficient Cl(-) homeostasis is crucial for...

BACKGROUND AND PURPOSE Mutations of the skeletal muscle sodium channel gene SCN4A, which is located on chromosome 17q23-25, are associated with various neuromuscular disorders that are labeled collectively as skeletal muscle sodium channelopathy. These disorders include hyperkalemic periodic paralysis (HYPP), hypokalemic periodic paralysis, paramyotonia congenita (PMC), potassium-aggravated myo...

Only recently, with the identification of antibodies to a 43-kDa muscle autoantigen, subsequently identified as cytoplasmic 50-nucleotidase 1A (cN1A) in sera from patients with inclusion body myositis (IBM), has a role for B-cell autoimmunity in IBM been demonstrated. IgG antibodies to cN1A have> 90% specificity and 34%–70% sensitivity in IBM. Detection of all 3 isotypes (IgG, IgM, and IgA) by ...

Here we present the case of a 32-year-old female patient with myotonia congenita. She carried two mutations in the CLCN1 gene that encodes the chloride channel ClC-1: p.Phe167Leu, which was previously identified in several families, and p.Val536Leu, which has been previously reported but not yet characterized by electrophysiological investigations. The patient's symptoms included generalized st...