[Congenital diseases of neuromuscular transmission: congenital myasthenia syndromes].

The congenital myasthenic syndrome constitute a group of genetic disorders affecting neuromuscular transmission. This group includes presynaptic as well as postsynaptic defects. In several congenital myasthenic syndromes, it was possible to characterize the underlying mechanism by applying modern in vitro electrophysiological methods, like single-channel recordings. These genetic disorders include defects of acetylcholine release, absence of the endplate-specific form of acetylcholinesterase, and kinetic abnormalities of the acetylcholine receptor. Recently several mutations of the acetylcholine receptor have been characterized. Clinical features of these syndromes, diagnostic work-up, and treatment are described in detail. These diseases present usually within the first 2 years of life, however, in some syndromes manifestation during adulthood is possible. The clinical spectrum ranges from mild muscle weakness to severe disability with lifethreatening episodes. Only some syndromes respond to acetylcholinesterase inhibitors. Further elucidation of these syndromes will not only lead to improved treatment, but should contribute to our understanding of synaptic transmission.