Lambert-Eaton Myasthenic Syndrome
The Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune condition, in which weakness is caused by blocked release of the neurotransmitter acetylcholine from the motor nerve terminal. This condition was first described in patients with lung cancer but we now know that it results from an immune-mediated process directed against the voltage-gated calcium channels (VGCC) on the nerve terminal. Half the patients with LEMS have lung cancer and in these patients, antibodies directed against cancer cell components cross-react with the VGCC on the nerve terminals. In patients without cancer, LEMS results when antibodies to the VGCC are produced as part of a more general autoimmune state. LEMS is probably the most well-understood autoimmune disease, and knowledge gained from studying how it begins has wide implications for other, more common, autoimmune diseases.
