126th International Workshop: Congenital Myasthenic Syndromes, 24–26 September 2004, Naarden, The Netherlands

Abstract

The ENMC hosted a group of 18 experts on Congenital Myasthenic Syndromes (CMS). CMS are inherited disorders in which the safety margin of the neuromuscular transmission is compromised by one or more specific mechanism(s). CMS are caused by various genetic defects. The objectives of the workshop included progress in deciphering the molecular basis of CMS (sessions 1–4) and clinical conclusions for epidemiology, diagnosis and therapy (sessions 5–7). To date, genes known to cause CMS if mutated are the presynaptic choline acetyltransferase gene CHAT, the gene COLQ encoding the synaptic protein ColQ, the genes encoding the different subunits of the postsynaptic acetylcholine receptor (CHRNA1, CHRNB1, CHRND, CHRNE), the genes for the postsynaptic proteins rapsyn (RAPSN), muscle-specific receptor tyrosine kinase (MUSK) and the postsynaptic sodium channel (SCN4A). Since the last ENMC workshop on CMS in October 1999, four novel CMS genes have been identified, namely CHAT, RAPSN, SCN4A and MUSK. As a consequence, several new patients presenting with varying phenotypes of CMS have been described worldwide. In particular, mutations in RAPSN and CHAT turned out to be of high clinical relevance, on one hand because of their apparent worldwide frequency, on the other hand because of their specific clinical phenotype with the occurrence of sudden apneic episodes. Furthermore, considerable progress has been made using a variety of