Brian Weinshenker:
About 25% of patients with neuromyelitis optica have other autoimmune diseases. We’ve seen almost every autoimmune disease you can imagine. The most common tend to be Lupus and Sjogren’s syndrome, but we’ve seen myasthenia gravis, which is a condition where the immune system attacks the muscle cells and it results in weakness. We’ll see patients diagnosed with neuromyelitis optica and they’ll tell us 10 years ago I had myasthenia gravis and we thought, “Well maybe this is just a coincidence.” But clearly it’s occurred or co-existed in patients with neuromyelitis optica, more than would be expected by just chance occurrence. So this is something that we really don’t understand. Why do these patients not only get aquaporin-4 specific autoimmunity, but get other autoimmune diseases? It’s not unprecedented, we know there are certain genes that when they’re mutated affect what’s called immunoregulation. Immunoregulation is a complex thing, but why doesn’t our immune system attack all of our tissues?
Brian Weinshenker:
When we were born, certain mechanisms caused us to be tolerant of our tissues and not attack all our own tissues. We even have mechanisms that if something escapes and abnormally forms an immune response, we have ways of controlling that and ways of getting rid of those rogue lymphocytes that get mixed up. But obviously something seems to get through and people with problems with certain genes and whether there’s a generalized problem like that in patients with neuromyelitis optica that may explain why they get other autoimmune diseases, we’re not sure, but it’s certainly something that, until we understand that, I don’t think we fully solved the riddle of neuromyelitis optica.