OBJECTIVE To characterize the clinical phenotype in patients with p.A1156T sodium channel mutation. METHODS Twenty-nine Finnish patients identified with the c.3466G>A p.A1156T mutation in the SCN4A gene were extensively examined. In a subsequent study, 63 patients with similar myalgic phenotype and with negative results in myotonic dystrophy type 2 genetic screening (DM2-neg group) and 93 pat...

Abnormal expression of human myotonic dystrophy protein kinase (hDMPK) gene products has been implicated in myotonic dystrophy type 1 (DM1), yet the impact of distress accumulation produced by persistent overexpression of this poorly understood member of the Rho kinase-related protein kinase gene-family remains unknown. Here, in the aged transgenic murine line carrying approximately 25 extra co...

A 7-month-old New Forest foal presented for episodes of recumbency and stiffness with myotonic discharges on electromyography. The observed phenotype resembled congenital myotonia caused by CLCN1 mutations in goats and humans. Mutation of the CLCN1 gene was considered as possible cause and mutation analysis was performed. The affected foal was homozygous for a missense mutation (c.1775A>C, p.D5...

PEARLS Adult-onset Pompe disease (acid maltase deficiency, glycogen storage disease type II) should be considered in the differential diagnosis in the adult patient presenting with slowly progressive selective lower extremity weakness, specifically of the hip flexors. Hip flexion weakness may be the only finding in the earliest stages of this disease. EMG findings of myotonic discharges occurri...

A 58-year-old woman presented with slowly-progressive lower limb weakness. Medical history disclosed a six-year history of obstructive sleep apnea syndrome (OSAS). Examination disclosed abnormal tongue features (Figure 1) and proximal flaccid tetraparesis. Muscle MRI showed marked compromise of the adductor magnus, and muscle biopsy disclosed vacuolar myopathy with PAS-positive vacuoles (Figure...

the myotonic disorders are a heterogeneous group of genetically determined diseases that are unified by the presence of myotonia, which is defined as failure of muscle relaxation after activation. the presentation of these disorders can range from asymptomatic electrical myotonia, as seen in some forms of myotonia congenita (mc), to severe disability with muscle weakness, cardiac conduction def...

Keywords: Myotonic dystrophy, Dystrophia Myotonica Protein Kinase (DMPK) gene, Epilepsy, Temporal lobe

Transmembrane chloride ion conductance in skeletal muscle increases during early postnatal development. A transgenic mouse model of myotonic dystrophy type 1 (DM1) displays decreased sarcolemmal chloride conductance. Both effects result from modulation of chloride channel 1 (CLCN1) expression, but the respective contributions of transcriptional vs. posttranscriptional regulation are unknown. He...

In myotonic dystrophy (dystrophia myotonica [DM]), an increase in the excitability of skeletal muscle leads to repetitive action potentials, stiffness, and delayed relaxation. This constellation of features, collectively known as myotonia, is associated with abnormal alternative splicing of the muscle-specific chloride channel (ClC-1) and reduced conductance of chloride ions in the sarcolemma. ...

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...