Neuromyelitis optica - Causes 

The exact cause of neuromyelitis optica (NMO) is not fully understood because very little is known about it. However, a number of factors that are thought to play a part are outlined below.

Genetics

NMO is not hereditary (it is very rarely found in more than one family member), but it is more common in people of Asian and African descent. This suggests that people with these genes (units of genetic material), may be predisposed (have a tendency) to develop the condition.

Infectious agents

An infectious agent is something that causes an infection. It is possible that NMO could be caused by an infectious agent. In rare cases, tuberculosis (a bacterial infection) and other environmental organisms have been associated with NMO, although no specific organism has yet been identified for being responsible.

Autoimmune disorder

NMO is an autoimmune disorder, which means that the immune system (your body's own defence system) starts to attack your tissues and organs. In NMO, your immune system attacks your myelin sheath (the protective covering that surrounds the optic nerve and spinal cord).

Antibodies

Research has found that about 70% people with NMO have an antibody called Neuromyelitis Optica Immunoglobin G (NMO lgG) present in their blood. An antibody is a protein that is produced by the body to destroy disease-carrying organisms and toxins.

It is thought that the NMO lgG antibody may influence the development of NMO by damaging the water channel (aquaporin 4) that surrounds the cells of the spinal cord and optic nerve.