Features include always present findings: Fatigable weakness, Low muscle tone (hypotonia), Weakness of facial musculature, and Tongue atrophy and others; and very common findings: Gowers sign. 28 total HPO annotations.

MUSK encodes muscle associated receptor tyrosine kinase (869 aa). Receptor tyrosine kinase which plays a central role in the formation and the maintenance of the neuromuscular junction (NMJ), the synapse between the motor neuron and the skeletal muscle. Highest expression in Small Intestine Terminal Ileum (3.1 TPM) and Bladder (1.9 TPM).

Congenital myasthenic syndrome 9 is associated with mutations in the MUSK gene on chromosome 9.

MUSK is classified as a druggable target (Clinically Actionable, Druggable Genome, Enzyme, Kinase, and Tyrosine Kinase categories) with score 2.6.

Genetic testing for MUSK is available. Testing is considered confirmatory for diagnosis.

Biomarker and diagnostic research for congenital myasthenic syndrome 9 has been reported in the published literature.

Phenotype severity distribution: 12 always present features, 1 very common feature, 9 common features.

No clinical trials have been registered for congenital myasthenic syndrome 9.

27 publications have been identified in PubMed for congenital myasthenic syndrome 9. Research spans Basic Science / Preclinical (26%), Epidemiology / Natural History (26%), and Case Report / Case Series (22%).