Résumé :
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Muscle channelopathies are a group of disorders which manifest by either weakness or stiffness resulting in periodic paralysis or myotonia. Improvements in diagnosis have now entered into clinical practice and are routinely provided to patients, thanks to the creation of reference and competence centers throughout the country. The combination of a careful clinical, ENMG and molecular analysis enable proper diagnosis. The major genes have been elucidated (genes encoding sodium, calcium and chloride channels). Even if patho-physiological mechanisms are better understood for chloride and sodium channelopathies, there is still unexplained features in the hypokalemic form of periodic paralysis. Notably, the cause of abnormal potassium fluxes remains obscure. Genes and mechanisms causing the thyrotoxic form of hypokalemic periodic paralysis were unknown. Recently, the first gene was discovered: it encodes a potassium channel. Mutations n this gene only explain a small proportion of the cases. Neonatal forms of muscle channelopathies have been recently recognized. Neo-mutations in the muscular sodium channel cause Severe Episodic Neonatal Laryngospasm (SNEL), a rare condition which can be dramatically improved by blockers of sodium channels. Medications improving patient condition in muscle channelopathies are available but they lack the proper demonstration of efficiency now required by regulatory agencies. Trials are therefore a priority to validate scales which can be used for therapeutic trials and to obtain administrative authorizations for drug prescription. This is a first step towards the discovery of new treatments.
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