A Natural History Study in Participants With Congenital Myasthenic Syndromes (CMS) Due to Mutations in DOK7, MUSK, AGRN, or LRP4

Inclusion Criteria:

* Can understand the requirements of the study and can provide written informed consent/assent, and willingness and ability to comply with the study protocol procedures
* Is male or female and aged ≥2 years at the time of providing informed consent/assent
* Has a diagnosis of CMS due to biallelic pathogenic mutations in DOK7 or any pathogenic mutations in MUSK, AGRN, or LRP4
* Has a total Quantitative Myasthenia Gravis (QMG) score of ≥3 (applies only to participants aged ≥6 years)
* For participants taking oral beta agonists (eg, albuterol, salbutamol, ephedrine), participant must have been receiving the medication for ≥3 months before screening/baseline

Exclusion Criteria:

* Known medical condition that would interfere with an accurate assessment of CMS, in the investigator's opinion
* Is currently participating in any interventional clinical study with a study drug at the time of providing informed consent/assent
* Diagnosis of CMS due to mutation of any gene other than DOK7, MUSK, AGRN, or LRP4