Female Speaker: 34-year old Allison Raney has lived in Washington State nearly all her life.

Allison Raney: I lived in Seattle at the training point of Pearl Jam and Nirvana right at those ages so it was really the musical scene.

Female Speaker: But in the medical community Seattle is known for something besides music.

Dr. Sylvia Lucas: Seattle probably has the highest prevalence of MS in the world.

Female Speaker: MS or Multiple Sclerosis is a progressive assault on the brain and spinal cord by the bodies own immune system.

Dr. Sylvia Lucas: It's your own immune system that's kind of gone out of whack and suddenly attacking things that are normal not viruses not bacteria but your own body.

Female Speaker: Women are two or three times more likely to be affected and the first symptoms often appear in early adulthood.

Allison Raney: When I first know that something was wrong with my health I was 22 and I had numbness on the right side of my body. I had vision problems I had double vision I had blurred vision.

Dr. Kathleen Costello: How you are able to move, how you are able to think to see, to speak, to swallow, the mood that you may be experiencing all can be affected by multiple sclerosis.

Female Speaker: Doctors don't know what causes MS, but they have identified a peculiar geographical pattern.

Dr. Sylvia Lucas: Seattle, Spokane Minnesota, Northern York, Scandinavian Countries, Britain they have a much higher rate of MS.

Dr. Randall Schapiro: As you move away from the equator north and south the amount of MS significantly increases and it seems that where you live your first 15 years of your life determines whether you are from a high risk area or a low risk area.

Dr. Sylvia Lucas: One of the popular theories that's being looked at now is the Vitamin D theory, may be we don't have enough Vitamin D and that puts us at risk.

Female Speaker: The body makes vitamin D in response to sunlight, something that's in short supply in the areas where MS is most prevalent.

Dr. Kathleen Costello: The father you get from the equator the less sun exposure the less natural vitamin D exposure that you are going to have. So is there a relationship there potentially it is. But I don't think it's been completely teased out.

Female Speaker: Some researchers believe a vitamin D deficiency could be one of several factors that cause the body's immune system to be behave abnormally. Other theories are that a virus or toxin may be to blame.

Dr. Sylvia Lucas: We don't know exactly what causes multiple sclerosis but we do know that there is probably an environmental risk as well as your genetic risk.

Female Speaker: Doctors hope that pinpointing the roots of MS could one day lead to strategies for prevention. In the mean time early diagnoses is crucial because there are therapies to slow the progression of the disease.

Allison Raney: Definitely its stuffed with energy and I am a little bit more stay will make not having balance issues as much just helps you keep walking forward. Just you have a disease but it's not the end of the world, you know I'm still Allison and I'm going to always be Allison.