This protocol provided 3,4 diaminopyridine (DAP) under a treatment-use IND to patients with congenital myasthenic syndrome (CMS). It is now closed.

CMS diagnoses were made based on clinical, electrophysiologic and molecular genetic findings. All patients were referred to the PI for DAP treatment. This study enrolled minors and adults.

CMS patients under age 18 years were included if their parent or guardian gave written permission. Minors who turned 18 while in the program were re-consented as adults.

The dose of DAP was determined individually for each patient. Adults were started with a dose of 10 mg 3-4 times daily, increased over several weeks to the dose that produced the maximum symptomatic response, not to exceed 100 mg daily. Pyridostigmine bromide (PB) was often added at low doses and increased to the dose that produced the best response, not to exceed 360 mg daily. In children, equivalent doses of these medications were calculated on a surface area basis. The doses of DAP and PB were periodically adjusted to assure that the smallest effective doses are used.

Inclusion Criteria:

• Diagnosis of congenital myasthenic syndrome (CMS)
• Women of childbearing potential must have negative pregnancy test and agree to practice adequate contraception while taking DAP
• Must be competent to give consent

Exclusion Criteria:

• Known seizure disorder
• Pregnancy
• Known cardiac arrhythmia or evidence of significant arrhythmia on screening ECG
• Known hepatic, renal or hematologic disease