Myotonia congenita is a human muscle disorder caused by mutations in CLCN1, which encodes human chloride channel 1 (CLCN1). Zebrafish is becoming an increasingly useful model for human diseases, including muscle disorders. In this study, we generated transgenic zebrafish expressing, under the control of a muscle specific promoter, human CLCN1 carrying mutations that have been identified in huma...

In addition to the hallmark muscle stiffness, patients with recessive myotonia congenita (Becker disease) experience debilitating bouts of transient weakness that remain poorly understood despite years study. We performed intracellular recordings from both genetic and pharmacologic mouse models Becker disease identify mechanism underlying weakness. Our reveal depolarizations (plateau potentials...

A 32-year-old woman with a 4-year history of multiple sclerosis presented with persistent clawing of the right hand. History revealed that she and five family members had lifelong symptoms of paradoxical myotonia (impaired relaxation of muscles following muscle contraction), exacerbated by cold. The family was diagnosed with paramyotonia congenita, based on neurophysiological and genetic studie...

The phenomenon of myotonia comprises a lingering relaxation of muscle after contraction, and a slow tonic response to stimuli of an electrical or mechanical nature. The condition may be ameliorated or even extinguished by repeated effort. Although well known and the commonest form of hereditary muscular disorder seen in young adults, it is, nevertheless, a rare condition. Three distinct forms o...

Non-dystrophic myotonia (NDM) is a group of rare mono-genetic muscle disorders caused by skeletal sodium or chloride channelopathies. These are characterized high tone and the inability muscles to relax spontaneously after voluntary contraction. Myotonia congenita refers form NDM that typically manifests during later stages childhood. It occurs as result genetic mutations affecting channels fou...

Clinical bedside tests to provoke myotonia, such as eyelid closure, handgrip, and percussion myotonia, help to diagnose and differentiate myotonic disorders and prevent delayed genetic confirmation. Sodium channelopathies present with predominantly myotonia of the ocular muscles. In these cases, testing for myotonia of the upper eyelid and extraocular muscles could be of decisive diagnostic val...

Paramyotonia congenita, the major characteristics of which are cold-induced and exercise-induced myotonia, is an autosomal-dominant muscle disease which is classified into one of a group of muscle diseases, so-called muscle "sodium channelopathies" caused by missense mutations in the gene coding for the skeletal muscle sodium channel a-subunit (SCN4A) (1-4). Such muscle sodium channelopathies s...