Congenital myasthenic syndromes are inherited disorders in which the safety margin of neuromuscular transmission is compromised by 1 or more specific mechanisms. Because they are relatively infrequent, they often go undiagnosed or misdiagnosed. Some congenital myasthenic syndromes can be diagnosed by clinical clues; others require special laboratory studies that define parameters of neuromuscular transmission and analyze the structure of the endplate. The genetic basis of no fewer than 30 congenital myasthenic disorders has now been identified, with 4 novel syndromes recognized since the last review. Most congenital myasthenic syndromes are treatable but therapy has to be tailored for the underlying molecular defect because therapies beneficial in some congenital myasthenic syndromes can be harmful in another type.
In this article, Dr. Andrew Engel of the Mayo Clinic College of Medicine provides an overview of the clinical aspects of the congenital myasthenic syndromes, describes their historical aspects and current classification, summarizes general and specific features of the different disorders, and considers their pathophysiology, pathogenesis, and prognosis.
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