We describe the case of a six year old boy with findings consistent with myotonia congenita: muscular hypertrophy, stiffness when commencing movements and typical warm-up signs. The most prominent symptom was myotonia of the eyelid muscles with apparent swelling around the eyes. Even though the pronounced warm-up phenomena in our patient suggested a chloride channel-associated myotonia congenit...

The single strand conformation polymorphism (SSCP) technique was used to screen genomic DNA of a family with myotonia aggravated by cold, potassium loading and suxamethonium, but without muscle weakness. An aberrant band was found in exon 24 of SCN4A, the gene encoding the adult skeletal muscle sodium channel alpha-subunit. DNA sequencing led to the detection of a G-to-A transition of cDNA nucl...

Hyperkalaemic periodic paralysis, paramyotonia congenita, and potassium-aggravated myotonia are three autosomal dominant skeletal muscle disorders linked to the SCN4A gene encoding the alpha-subunit of the human voltage-sensitive sodium channel. To date, approximately 20 point mutations causing these disorders have been described. We have identified a new point mutation, in the SCN4A gene, in a...

OBJECTIVES Acetazolamide has been the most commonly used treatment for hypokalemic periodic paralysis since 1968. However, its mechanism of efficacy is not fully understood, and it is not known whether therapy response relates to genotype. We undertook a clinical and genetic study to evaluate the response rate of patients treated with acetazolamide and to investigate possible correlations betwe...

INTRODUCTION Hyperkalemic periodic paralysis (HYPP) is an autosomal dominant disease characterized by recurrent episodes of muscular weakness with increased blood potassium levels. Here we present the clinical, analytical, neurophysiological and genetic findings of family with eight affected individuals, five of which were available for study. PATIENTS AND METHODS The five patients were subje...

Dear Editor, Myotonia congenita (MC) is a group of genetically and clinically heterogeneous congenital neuromuscular channelopathies characterized by the delayed relaxation of the muscles after voluntary contraction, stiffness, hypertrophy, transient weakness, and cramping. MC is mostly associated with dominant or recessive mutations in CLCN1. However, SCN4A mutations are occasionally implicate...