What causes Lambert Eaton myasthenic syndrome (LEMS)?
LEMS is a disorder of the immune system, also known as an autoimmune disorder. Autoimmune disorders occur when the body's defense system against foreign organisms (antibodies) attack healthy tissue. LEMS occurs when part of the neuromuscular junction is damaged. The neuromuscular junction is the area between a nerve cell and a muscle cell, where communication occurs through the release of a chemical signal, called acetylcholine (ACh). This results in muscle contraction or movement. When individuals have LEMS, this process is blocked and ACh is not effectively released from nerve cells.
In instances where LEMS is associated with cancer, the cause may be related to the body’s attempt to fight the cancer and accidental attack of nerve fiber endings, especially the voltage-gated calcium channels found there. The trigger for the cases not associated with cancer is unknown.
Last updated: 12/22/2016
Is Lambert Eaton myasthenic syndrome (LEMS) genetic?
The answer to this question is complex. While the condition is not known to follow a specific pattern of inheritance, there appears to be a genetic predisposition to autoimmune diseases in general. Families with a history of Lambert Eaton myasthenic syndrome may benefit from consulting with a genetics professional.
Last updated: 12/23/2016
How can I find a genetics professional in my area?
Verbeek, S. et al. Lambert–Eaton myasthenic syndrome in a 13-year-old girl with Xp11.22-p11.23 duplication. European Journal of Paediatric Neurology. May 2014; 18(3):439-443. https://www.ncbi.nlm.nih.gov/pubmed/24461257.