INBORN DISEASES OF NEUROMUSCULAR-TRANSMIS SION - CONGENITAL MYASTHENIC SYNDROMES

The congenital myasthenic syndrome constitute a group of genetic disor ders affecting neuromuscular transmission. This group includes presyna ptic as well as postsynaptic defects. In several congenital myasthenic syndromes, it was possible to characterize the underlying mechanism b y applying modern in vitro electrophysiological methods, like single-c hannel recordings. These genetic disorders include defects of acetylch oline release, absence of the endplate specific form of acetylcholines terase, and kinetic abnormalities of the acetylcholine receptor. Recen tly several mutations of the acetylcholine receptor have been characte rized. Clinical features of these syndromes, diagnostic work-up, and t reatment are described in detail. These diseases present usually withi n the first 2 years of life, however in some syndromes manifestation d uring adulthood is possible. The clinical spectrum ranges from mild mu scle weakness to severe disability with lifethreatening episodes. Only some syndromes respond to acetylcholinesterase in hibitors. Further e lucidation of these syndromes will not only lead to improved treatment , but should contribute to our under standing of synaptic transmission .