title: What have we learned from the congenital myasthenic syndromes.
abstract: The congenital myasthenic syndromes have now been traced to an array of molecular targets at the neuromuscular junction encoded by no fewer than 11 disease genes. The disease genes were identified by the candidate gene approach, using clues derived from clinical, electrophysiological, cytochemical, and ultrastructural features. For example, electrophysiologic studies in patients suffering from sudden episodes of apnea pointed to a defect in acetylcholine resynthesis and CHAT as the candidate gene (Ohno et al., Proc Natl Acad Sci USA 98:2017-2022, 2001); refractoriness to anticholinesterase medications and partial or complete absence of acetylcholinesterase (AChE) from the endplates (EPs) has pointed to one of the two genes (COLQ and ACHE ( T )) encoding AChE, though mutations were observed only in COLQ. After a series of patients carrying mutations in a disease gene have been identified, the emerging genotype-phenotype correlations provided clues for targeted mutation analysis in other patients. Mutations in EP-specific proteins also prompted expression studies that proved pathogenicity, highlighted important functional domains of the abnormal proteins, and pointed to rational therapy.
authors.affiliation: Department of Neurology and Muscle Research Laboratory, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. age@mayo.edu
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Engel
authors.forename: Xin-Ming
authors.initials: XM
authors.lastname: Shen
authors.forename: Duygu
authors.initials: D
authors.lastname: Selcen
authors.forename: Steven M
authors.initials: SM
authors.lastname: Sine
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000110:Acetylcholinesterase / Q000235:genetics; D002795:Choline O-Acetyltransferase / Q000235:genetics; D004252:DNA Mutational Analysis / Q000379:methods; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D008967:Molecular Biology / Q000379:methods / Q000639:trends*; D009154:Mutation / Q000235:genetics; D020294:Myasthenic Syndromes, Congenital / Q000201:enzymology* / Q000235:genetics* / Q000503:physiopathology; D009469:Neuromuscular Junction / Q000201:enzymology* / Q000235:genetics* / Q000503:physiopathology
chemical_list: D002795:Choline O-Acetyltransferase; D000110:Acetylcholinesterase; D000109:Acetylcholine
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