Congenital Myasthenic Syndrome 2A is a muscular disorder characterized by hypotonia, motor developmental delay, limb muscle weakness and muscle atrophy, as well as musculoskeletal abnormalities including joint contractures, and eye abnormalities including ptosis and ophthalmoplegia. Additional characteristics include dysmorphic facial features (e.g. thin long face). This disorder may be onset at birth and is diagnosed through family history, appearance of clinical features, muscle fiber electromyography tests, and response to therapy.
This disorder is caused by prolonged activity of acetylcholine receptors which function on the postsynaptic side of the neuromuscular junction; the resulting damage to the connection between nerve and muscle cells produces the abnormal motor and muscular clinical features. Management therapy currently involves the use of open-channel blockers such as quinine, quinidine, and fluoxetine.