No abstract available.
Humans ; Myotonia Congenita* ; Myotonia*

No abstract available.
Dyskinesias ; Myotonia Congenita ; Myotonia

Myotonia congenita (MC) is a hereditary disease of the chloride channels of skeletal muscle caused by mutation of CLCN1. It characteristically manifests as delayed relaxation of the skeletal muscle or myotonia. It has a wide phenotypic variability, ranging from asymptomatic to severe disability. However, it is uncommon for a phenotypic difference to appear within a family. We report the first Korean family with the p.A313T mutation exhibiting marked phenotypic variability.
Chloride Channels ; Genetic Diseases, Inborn ; Humans ; Muscle, Skeletal ; Myotonia Congenita* ; Myotonia* ; Relaxation

Congenital myotonia is a benign familial disorder, main problem is muscle stiffness, delayed relaxation of skeletal muscles after voluntary contraction or following mechanical or electrical stimulation. Although weakness is always present with progression of myotonic dystrophy, many patients with myotonia congenita never develop weakness. In the autosomal dominantly inherited form of congenital myotonia (Thomsen's disease), symptoms revolve around myotonia but weakness is not present. However, in the autosomal recessive (Becker's) type congenital myotonia, mild weakness and marked muscle hypertrophy is common. We report two cases of sporadic developing Becker's type congenital myotonia with electrophysiologic and muscle biopsy findings and review of literatures.
Biopsy ; Electric Stimulation ; Humans ; Hypertrophy ; Muscle, Skeletal ; Myotonia ; Myotonia Congenita* ; Myotonic Dystrophy ; Relaxation

Congenital myotonia is a hereditary disorder of the skeletal muscle. The most characteristic features of the disease are myotonia and variable muscular hypertrophy. Molecular biologic investigations have revealed that mutations in the gene of the human skeletal muscle chloride ion channel protein are a cause of the disease. The Becker's type congenial myotonia is clinically similar to the autosomal dominantly inherited congenital myotonia (Thomsen's disease). Both disorders are characterized electrophysiologically by increased excitability of muscle fibers, reflected in clinical myotonia. In general, Becker's type congenital myotonia is more severe than Thomsen's disease in muscular hypertrophy and weakness. The authors recently experienced a 25-year-old female patient who has no family-related disease history and who has conspicuous muscular hypertrophy and the stiffness with muscles which occurred from the age of 3 or 4. Clinically she showed the authors a percussion myotonia. On electrophysiological study, exercise and repetitive stimulation of the abductor digiti quinti muscle disclosed a decline in the compound muscle action potential. Biopsy of biceps muscle revealed enlargement of muscle fibers with marked nuclear internalization. After the oral taking the Mexiletine, the patient showed a favorable turn a little with her stiffness of muscles. So we authors are reporting one case of Becker's type congenital myotonia with review of literatures.
Action Potentials ; Adult ; Biopsy ; Chloride Channels ; Female ; Humans ; Hypertrophy ; Mexiletine ; Muscle, Skeletal ; Muscles ; Myotonia ; Myotonia Congenita*

Myotonia dystrophica(Synonym: Myotonia atrophica, Dystrophia myotonia, Steinert's disease) is a autosomal dominant hereditary multisystemic disorder involving several organs besides skeletal muscle, and commonly called with myotonia congenita, paramyotonia congenita as myotonia. Although most cases are of adult onset, where a mother has the disease, neonatal dystrophia myotonia can occur in her offspring. The main feature is a steadily progressive muscle dystrophy, complicated by myotonia, which is a failure of muscles to relax normally after a forceful contraction. Steinert in 1909 was the first to report the finding of atrophic testes and baldness in patients with myotonia dystrophica, and the other clinical feature of myotonia dystrophica were reported by many authors after that time. We are reporting a case of myotonia dystrophica, which showing familial history with brief review of literature.
Adult ; Alopecia ; Humans ; Mothers ; Muscle, Skeletal ; Muscles ; Myotonia Congenita ; Myotonia ; Myotonic Disorders ; Myotonic Dystrophy ; Testis

BACKGROUND AND PURPOSE: While the etiology and clinical features of "EMG disease" - which is characterized by diffusely increased insertional activity on needle electromyography (EMG) in the absence of neuromuscular disease - are not well known, some authorities believe it may be a form of myotonia congenita (MC). The aims of this study were to determine the clinical features of EMG disease and its relationship with CLCN1 mutations in patients. METHODS: The detailed clinical and electrophysiological features of EMG disease were evaluated in six patients. All 23 coding exons and exon-intron boundaries in CLCN1 gene were analyzed by direct sequencing to detect nucleotide changes. RESULTS: The common clinical symptoms of EMG disease were chronic muscle stiffness or generalized myalgia, which were aggravated in a cold environment. Four patients complained of action myotonia several times a year. Short trains of provoked positive sharp waves were documented on needle EMG, but myotonic discharges, fibrillation potentials, and fasciculations were not. Increased insertional activity was identified at the asymptomatic muscles studied. One novel heterozygous mutation was identified in one patient following genetic testing for CLCN1 mutations (c.1679T>C, p.Met560Thr). CONCLUSIONS: The clinical features of EMG disease might be quite similar to those of MC, but CLCN1 mutation was found in only one subject. It is thus difficult to accept that EMG disease lies within the phenotypic spectrum of MC. Additional testing is needed to verify the pathogenetic cause of the diffusely increased insertional activity associated with this condition.
Chloride Channels ; Clinical Coding ; Cold Temperature ; Electromyography ; Exons ; Fasciculation ; Genetic Testing ; Humans ; Muscles ; Myotonia ; Myotonia Congenita ; Needles ; Neuromuscular Diseases

OBJECTIVETo investigate chloride channel 1 (CLCN1) gene mutation and clinical features of 2 Chinese patients with myotonia congenita.

METHODSClinical data of a patient from a family affected with myotonia congenita in addition with a sporadic patient from Fujian province were analyzed. Exons of CLCN1 gene were amplified and sequenced.

RESULTSThe proband from the affected family was found to carry a c.1024G>A heterozygous missense mutation in exon 8, whilst the sporadic patient has carried a c.1292C>T heterozygous missense mutation in exon 11.

CONCLUSIONDetection of CLCN1 gene mutation is an effective method for the diagnosis of myotonia congenita. Exon 8 of CLCN1 gene may be a mutational hotspot in Chinese patients with myotonia congenita.

Adolescent ; Base Sequence ; Chloride Channels ; genetics ; Exons ; Heterozygote ; Humans ; Male ; Mutation ; Myotonia Congenita ; diagnosis ; genetics ; Pedigree

Humans ; Myotonia Congenita/genetics* ; Mutation ; NAV1.4 Voltage-Gated Sodium Channel/genetics*

Myotonia congenita (MC) is a genetic disease that displays impaired relaxation of skeletal muscle and muscle hypertrophy. This disease is mainly caused by mutations of CLCN1 that encodes human skeletal muscle chloride channel (CLC-1). CLC-1 is a voltage gated chloride channel that activates upon depolarizing potentials and play a major role in stabilization of resting membrane potentials in skeletal muscle. In this study, we report 4 unrelated Korean patients diagnosed with myotonia congenita and their clinical features. Sequence analysis of all coding regions of the patients was performed and mutation, R47W and A298T, was commonly identified. The patients commonly displayed transient muscle weakness and only one patient was diagnosed with autosomal dominant type of myotonia congenita. To investigate the pathological role of the mutation, electrophysiological analysis was also performed in HEK 293 cells transiently expressing homo- or heterodimeric mutant channels. The mutant channels displayed reduced chloride current density and altered channel gating. However, the effect of A298T on channel gating was reduced with the presence of R47W in the same allele. This analysis suggests that impaired CLC-1 channel function can cause myotonia congenita and that R47W has a protective effect on A298T in relation to channel gating. Our results provide clinical features of Korean myotonia congenita patients who have the heterozygous mutation and reveal underlying pathophyological consequences of the mutants by taking electrophysiological approach.
Alleles ; Chloride Channels ; Clinical Coding ; Electrophysiology ; HEK293 Cells ; Humans ; Hypertrophy ; Membrane Potentials ; Muscle Weakness ; Muscle, Skeletal ; Myotonia Congenita* ; Myotonia* ; Relaxation ; Sequence Analysis