OBJECTIVE To redefine phenotypical characteristics for both chloride (ClCh) and sodium channelopathies (NaCh) in non-dystrophic myotonic syndromes (NDM). METHODS In a cross-sectional, nationwide study, standardised interviews and clinical bedside tests were performed in 62 genetically confirmed NDM patients, 32 ClCh and 30 NaCh. RESULTS Standardised interviews revealed that ClCh reported a ...

U12 snRNA is required for branch point recognition in the U12-dependent spliceosome. Using site-specific cross-linking, we have captured an unexpected interaction between the 5' end of the U12 snRNA and the -2 position upstream of the 5' splice site of P120 and SCN4a splicing substrates. The U12 snRNA nucleotides that contact the 5' exon are the same ones that form the catalytically important h...

The group of dominant non-dystrophic myotonias, comprising disorders characterized by clinically similar forms of myogenic muscle stiffness, is genetically inhomogeneous. Dominant myotonia congenita (Thomsen's disease) is linked to CLCN1, the gene encoding the major muscle chloride channel, localized on chromosome 7q35. In contrast, dominant myotonias sensitive to potassium are caused by point ...

OBJECTIVE To characterize the phenotype of patients with symptoms of periodic paralysis (PP) and ryanodine receptor (RYR1) gene mutations. METHODS Cases with a possible diagnosis of PP but additional clinicopathologic findings previously associated with RYR1-related disorders were referred for a tertiary neuromuscular clinical assessment in which they underwent detailed clinical evaluation, i...

Polyglutamine expansions in the huntingtin gene cause Huntington's disease (HD). Huntingtin is ubiquitously expressed, leading to pathological alterations also in peripheral organs. Variations in the length of the polyglutamine tract explain up to 70% of the age-at-onset variance, with the rest of the variance attributed to genetic and environmental modifiers. To identify novel disease modifier...

Here we report the molecular characterization of Out-cold (Ocd) mutants of Drosophila melanogaster, which produce a dominant, X-linked, cold-sensitive paralytic phenotype. From its initial 1.5-Mb cytological location within 13F1-16A2, P-element and SNP mapping reduced the Ocd critical region to <100 kb and to six candidate genes: hangover, CG9947, CG4420, eIF2a, Rbp2, and paralytic (para). Comp...

Neck ventroflexion in cats has different causes; however, the most common is the hypokalemia associated with flaccid paralysis secondary to chronic renal failure. In humans, the most common causes of acute flaccid paralysis are hypokalemia precipitated by thyrotoxicosis and familial forms linked to mutations in sodium, potassium, and calcium channel genes. Here, we describe the sequencing and a...

In 1865, Claude Bernard wrote that ‘the constancy of the internal milieu is the essential condition to a free and independent life’ [1]. It would be hard to find a more illustrative paradigm for that statement than for the case of hyperkalaemic periodic paralysis (HyperPP) reported by Grgic et al. in this issue [2]. A 14-year-old male was admitted for a sudden ascending paralysis involving the ...

Myoclonus is a sudden brief, involuntary muscle jerk. Of all the movement disorders, myoclonus is the most difficult to encapsulate into any simple framework. On the one hand, a classification system is required that is clinically useful to aid in guiding diagnosis and treatment. On the other hand, there is need for a system that organizes current knowledge regarding biological mechanisms to gu...

We isolated two full-length cDNA clones from the adult murine heart that encode two different voltage-gated Na+ channels: mH1 and mH2. Sequence comparisons indicated that mH1 is highly homologous to rat SCN5A, whereas mH2 is highly homologous to SCN4A, expressed in rat skeletal muscle. Electrophysiological properties of mH1 channels strongly resembled the tetrodotoxin (TTX)-resistant Na+ curren...