CNS: central nervous system; EMG: electromyography; NCS: nerve conduction study; CSF: cerebrospinal fluid; IVIG: IV immunoglobulin; MG: myasthenia gravis; LEMS: Lambert-Eaton myasthenic syndrome; AchR: acetylcholine receptor; MuSK: muscle-specific kinase. The gene discussed is MUSK; the disease is Lambert-Eaton myasthenic syndrome.