congenital recessive myotonia is a rare genetic disorder caused by mutations in clcn1, which codes for the main skeletal muscle chloride channel clc-1. more than 120 mutations have been found in this gene. the main feature of this disorder is muscle membrane hyperexcitability. here, we report a 59-year male patient suffering from congenital myotonia. he had transient generalized myotonia, which...

Myotonia congenita (MC) is a genetic disease caused by mutations in the skeletal muscle chloride channel gene (CLCN1) encoding the skeletal muscle chloride channel (ClC-1). Mutations of CLCN1 result in either autosomal dominant MC (Thomsen disease) or autosomal recessive MC (Becker disease). The ClC-1 protein is a homodimer with a separate ion pore within each monomer. Mutations causing recessi...

BACKGROUND Muscle magnetic resonance imaging (MRI) is the most sensitive method in the detection of dystrophic and non-dystrophic abnormalities within striated muscles. We hypothesized that in severe myotonia congenita type Becker muscle stiffness, prolonged transient weakness and muscle hypertrophy might finally result in morphologic skeletal muscle alterations reflected by MRI signal changes....

PRODUCTIVE INVESTIGATIONS of disease mechanisms that also reveal new information about normal regulation elicit a particularly satisfying sense of a two-for-one deal. In the case of Lueck et al. (Ref. 13; see page 1291 of this issue), a detailed study of the molecular basis for the myotonia (delayed relaxation of muscle contraction) observed in individuals with myotonic dystrophy, type 1 (DM1) ...

Myotonic dystrophy type 1 (DM1) is a genetic disorder characterized by muscle wasting, myotonia, cataracts, cardiac arrhythmia, hyperinsulinism and intellectual deficits, and is caused by expansion of a CTG repeat in the 3'UTR of the Dystrophia Myotonica-Protein Kinase (DMPK) gene. The DMPK transcripts containing expanded CUG repeats accumulate in nuclear foci and ultimately cause mis-splicing ...

Myotonia congenita (MC) is a skeletal muscle channelopathy characterized by inability of the muscle to relax following voluntary contraction. Worldwide population prevalence in humans is 1:100,000. Studies in mice, dogs, humans and goats confirmed myotonia associated with functional defects in chloride channels and mutations in a skeletal muscle chloride channel (CLCN1). CLCN1 encodes for the m...

Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy in adults and as yet no cure for DM1. Here, we report the potential of manumycin A for a novel DM1 therapeutic reagent. DM1 is caused by expansion of CTG repeat. Mutant transcripts containing expanded CUG repeats lead to aberrant regulation of alternative splicing. Myotonia (delayed muscle relaxation) is the most commonly obs...

OBJECTIVE The objective of this study was to validate the immunohistochemical assay for the diagnosis of nondystrophic myotonia and to provide full clarification of clinical disease to patients in whom basic genetic testing has failed to do so. METHODS An immunohistochemical assay of sarcolemmal chloride channel abundance using 2 different ClC1-specific antibodies. RESULTS This method led t...

Myotonia congenita (MC) is the commonest genetic skeletal muscle ion channelopathy. It is caused by mutations in CLCN1 on chromosome 7q35, which alter the function of the major skeletal muscle voltage-gated chloride channel. Dominant and recessive forms of the disease exist. We have undertaken a clinical, genetic and molecular expression study based upon a large cohort of over 300 UK patients. ...

Myotonia is a condition characterized by impaired relaxation of muscle following sudden forceful contraction. We systematically screened all 23 exons of the CLCN1 gene in 88 unrelated patients with myotonia and identified mutations in 14 patients. Six novel mutations were discovered: five were missense (S132C, L283F, T310M, F428S and T550M) found in heterozygous patients, and one was a nonsense...