This report describes general characteristics of the group of diseases classified as congenital myasthenic syndrome (CMS). CMS is a genetically heterogeneous disorder, with multiple implicated genes and mapped loci. A comprehensive list of CMS subtypes, as defined by OMIM, can be found by following the link in the "OMIM phenotypic series" section, below. At this time, only one subtype has been modeled in flies.
[updated Oct. 2016 by FlyBase; FBrf0222196]
Congenital myasthenic syndrome is a group of conditions characterized by muscle weakness (myasthenia) that worsens with physical exertion. The muscle weakness typically begins in early childhood but can also appear in adolescence or adulthood. Facial muscles, including muscles that control the eyelids, muscles that move the eyes, and muscles used for chewing and swallowing, are most commonly affected. However, any of the muscles used for movement (skeletal muscles) can be affected in this condition. Due to muscle weakness, affected infants may have feeding difficulties. Development of motor skills such as crawling or walking may be delayed. The severity of the myasthenia varies greatly, with some people experiencing minor weakness and others having such severe weakness that they are unable to walk. [from Genetics Home Reference, congenital myasthenic syndrome; 2016.10.07]
Congenital myasthenic syndromes (CMS) are a group of inherited disorders affecting the neuromuscular junction (NMJ). Patients present clinically with onset of variable muscle weakness between infancy and adulthood. These disorders have been classified according to the location of the NMJ defect: presynaptic, synaptic, and postsynaptic. [from MIM:616040; 2016.10.07]
