Hereditary muscle channelopathies are caused by dominant mutations in the genes encoding for subunits of muscle voltage-gated ion channels. Point mutations on the human skeletal muscle Na+ channel (Nav1.4) give rise to hyperkalemic periodic paralysis, potassium aggravated myotonia, paramyotonia congenita and hypokalemic periodic paralysis type 2. Point mutations on the human skeletal muscle Ca2...

Mutations in the voltage-dependent skeletal muscle chloride channel, ClC-1, result in dominant or recessive myotonia congenita. The Q552R mutation causes a variant of dominant myotonia with a milder phenotype, myotonia levior. To characterise the functional properties of this mutation, homodimeric mutant and heterodimeric wild-type (WT) mutant channels were expressed in tsA201 cells and studied...

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 generation of action potentials in excitable cells requires selective ion channels that open and close upon changes in membrane potential. Initially, cell excitabil-ity was mainly studied in neuronal axons, and in this particular cell compartment, electrical excitability is almost exclusively governed by cation channels. For many years, voltage-dependent anion channels were thought to be of...

Myotonia congenita (MC) is a form of nondystrophic myotonia caused by a mutation of CLCN1, which encodes human skeletal muscle chloride channel (CLC-1). We performed sequence analysis of all coding regions of CLCN1 in patients clinically diagnosed with MC, and identified 10 unrelated Korean patients harboring mutations. Detailed clinical analysis was performed in these patients to identify thei...

The chromosomal localization of the gene for Thomsen disease, an autosomal dominant form of myotonia congenita, is unknown. Electrophysiologic data in Thomsen disease point to defects in muscle-membrane ion-channel function. A mouse model of myotonia congenita appears to result from transposon inactivation of a muscle chloride-channel gene which maps to a region of mouse chromosome 6. The linka...

An epidemiological and genetic investigation of myotonia congenita was carried out in northern Finland. Altogether 58 patients were identified (of whom 54 lived in the study area) in 23 families, with a prevalence of 7.3 per 100000. The majority of the families originated from a sparsely populated area in western Lapland. The mean age at onset of the disease was 11 years with a range of 2 to 45...

Myotonia congenita is a rare muscular disorder with autosomal dominant or autosomal recessive inheritance, and is characterized by painless myotonia. A 44-year-old mother presented at our clinic with a son and a daughter, all sharing the same complaints of difficulty in relaxing their hands and beginning to walk, and spasms during chewing. The family had also another 16-year-old daughter, but s...

Paramyotonia congenita is a non-progressive disease characterised by myotonia (failure of muscle relaxation) induced by the exposure of the affected muscles to cold. Episodes of flaccid paralysis occur and may be related to hyperkalaemic periodic paralysis. Proximal myopathy or muscular hypertrophy may occur. The condition is inherited as an autosomal dominant.' Severe paralysis may occur with ...

Sirs: Myotonia is a clinical phenomenon consisting of uncontrolled temporary muscle stiffness after voluntary or evoked muscle contractions [1]. It is a cardinal symptom in non-dystrophic myotonias, including chloride and sodium channelopathies. Myotonia typically occurs after a period of rest and decreases with continuing exercise, commonly referred to as the warm-up phenomenon. This is in con...