U.S. flag

An official website of the United States government

GTR Home > Conditions/Phenotypes > Congenital myasthenic syndrome 3B

Congenital myasthenic syndrome 3B

Synonyms
CHRND-Related Congenital Myasthenic Syndrome; Myasthenic syndrome, congenital, 3B, fast-channel

Summary

Fast-channel congenital myasthenic syndrome (FCCMS) is a disorder of the postsynaptic neuromuscular junction (NMJ) characterized by early-onset progressive muscle weakness. The disorder results from kinetic abnormalities of the acetylcholine receptor channel, specifically from abnormally brief opening and activity of the channel, with a rapid decay in endplate current and a failure to reach the threshold for depolarization. Treatment with pyridostigmine or amifampridine may be helpful; quinine, quinidine, and fluoxetine should be avoided (summary by Sine et al., 2003 and Engel et al., 2015). For a discussion of genetic heterogeneity of CMS, see CMS1A (601462). [from OMIM]

Available tests

28 tests are in the database for this condition.

Clinical tests (28 available)

Molecular Genetics Tests

Genes See tests for all associated and related genes

  • Also known as: ACHRD, CMS2A, CMS3A, CMS3B, CMS3C, FCCMS, SCCMS, CHRND
    Summary: cholinergic receptor nicotinic delta subunit

Clinical features

Help
Imported from Human Phenotype Ontology (HPO)

Show allHide all

IMPORTANT NOTE: NIH does not independently verify information submitted to the GTR; it relies on submitters to provide information that is accurate and not misleading. NIH makes no endorsements of tests or laboratories listed in the GTR. GTR is not a substitute for medical advice. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.