Juvenile myasthenia gravis (JMG) is a rare autoimmune disease affecting the neuromuscular endplate, thus impairing the neuromuscular transmission giving fatigable muscle weakness. The disease is potentially lethal and correct diagnosis is essential since several treatment options including immunosuppressive medication and thymectomy, are available.

The overall aim of this thesis was to characterize the clinical aspects of JMG in Norway, especially focusing on symptoms, comorbidity, treatment and long-term outcome, as well as genetic risk factors.

JMG patients were identified through multiple strategies and 63 patients, classified as either prepubertal (