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congenital myasthenic syndrome 2A (CMS2A) - Clinical Profile, Genes & Research | Kisho | Kisho

Rare Disease

congenital myasthenic syndrome 2A

MONDO:0014581

Also known as:CMS2Acongenital myasthenic syndrome 2A slow-channelcongenital myasthenic syndrome type 2A

Overview

A congenital myasthenic syndrome characterized by autosomal dominant inheritance of postsynaptic neuromuscular junction defects, early-onset progressive muscle weakness, and prolonged opening and activity of the acetylcholine receptor channel that has material basis in heterozygous mutation in the CHRNB1 gene on chromosome 17p13.

GeneticsAutosomal dominant · CHRNB1 (chr 17)

OnsetINFANTILE, CONGENITAL, NEONATAL, JUVENILE

Clinical Presentation

Built from Human Phenotype Ontology (HPO) phenotype annotations and GeneReviews clinical descriptions. Features represent findings documented across known cases — not an exhaustive list of possible symptoms.

Features include always present findings: Poor head control, Muscle fiber splitting, Flexion contracture, and Fatigable weakness and others. 25 total HPO annotations.

Organ System	Phenotype Count	Example Features
Muscles	12	Muscle fiber splitting, Myopathy, Flexion contracture

Genetic Landscape

Assembled from HGNC gene records, ClinGen gene-disease validity evidence, and ClinVar pathogenic variant data. Validity classifications reflect the strength of published evidence linking each gene to this disease.

CHRNB1 encodes cholinergic receptor nicotinic beta 1 subunit (501 aa). After binding acetylcholine, the AChR responds by an extensive change in conformation that affects all subunits and leads to opening of an ion-conducting channel across the plasma membrane

Congenital myasthenic syndrome 2A has been associated with mutations in the CHRNB1 gene on chromosome 17.

CHRNB1 is classified as a druggable target (Druggable Genome, Ion Channel, and Transporter categories) with score 0.5.

Diagnosis

Genetic testing for CHRNB1 is available. Testing is considered supportive for diagnosis.

Prognosis

Phenotype severity distribution: 19 always present features.

Research Landscape

Sourced from ClinicalTrials.gov and PubMed. Publication types are classified using NLM-curated article metadata; research type breakdowns reflect the nature of published work for this disease.

No clinical trials have been registered for congenital myasthenic syndrome 2A.

11 publications have been identified in PubMed for congenital myasthenic syndrome 2A. Research spans Review / Meta-Analysis (27%), Basic Science / Preclinical (27%), and Epidemiology / Natural History (27%).

Research Type	Count	% of Total
Research summaries	3	27%

Data assembled from 6 of 12 sources · Last updated Oct 3, 2026, 8:12 PM UTC

MONDOHPOClinicalTrials.govFDAPubMedHGNCClinVarClinGenGeneReviewsOrphanetOMIMRUSP

Medical References

External Resources

OMIM

Online Mendelian Inheritance in Man

OMIM:616313

GARD

Genetic and Rare Diseases Info Center

GARD:9895

Questions for Your Care Team

→Should I pursue genetic testing for CHRNB1, and what would the results mean for my family?
→Are there specialists or centers of excellence for this condition in my area?
→Is there a patient registry I should consider joining?

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congenital myasthenic syndrome 2A

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Research Landscape

Medical References

External Resources

OMIM

GARD

Questions for Your Care Team

Questions for Your Care Team

Explore clinical features

Recent Publications

congenital myasthenic syndrome 2A

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Prognosis

Research Landscape

Medical References

External Resources

OMIM

GARD

Related Diseases

Questions for Your Care Team

Questions for Your Care Team

Explore clinical features

Recent Publications