Incidence and Demographics
MMN is a rare disease probably affecting no more than 1-2 in 100,000 people. Men are twice as likely as women to be affected. Most patients are in their 40’s to 60’s, although MMN has been described between the ages of 20 and 80. The disorder can cause significant disability but does not shorten life. It is extremely rare for MMN to cause problems with breathing or swallowing. It is rare that MMN will go into remission. In some cases, MMN will initially respond to treatment (see “Therapy” section) but then stop responding to treatment and remain stable.
Cause of MMN
MMN is thought to be caused by alterations in the immune system, such that certain proteins (antibodies) that would normally protect one from viruses and bacteria begin to attack constituents of peripheral nerves. Antibodies may be directed against “GM-1”, a ganglioside located at the Node of Ranvier. These antibodies have been detected in at least one third of MMN patients. More recent studies also suggest that newer tests for antibodies directed against GM-1 combined with a number of related gangliosides, are positive in over 80% of MMN patients. Thus, there are increasing reasons to believe these antibodies are the cause of MMN.