Thanks Q for the excellent information that I'm sure many will find useful. You sure do know you stuff!
That is so interesting, isn't it? I am Caucasian of northern European ancestry living in the Pacific Northwest - and have all my life! Do I fit the profile or what?!
People from Youchoko don't get MS because they wither in childhood from Twinkie deprivation.
It's hard to talk about racial or ethnic tendencies because they don't occur in a vacuum. They are affected by locale and are known to be evolving with different patterns. There are even multiple data that suggest an infectious component plays some role too.
Racial Risk
MS is commonest in Caucasions, especially of Northern European ancestry.. It is very low risk in Blacks, low risk in Native Americans and the Native populations of Central and South America. It is much lower in the northern natives, such as the Eskimos. It is low in Asians
Ethnicity
Worldwide the groups at highest risk have northern European ancestry. This includes northern US, Southern Canada, Europe, Russia, New Zealand and the Southeastern portion of Australia. The prevalence in these areas is in the range of 60 to 350 cases of MS per 100,000 of population. Hotbeds do occur. The Orkney Islands off Scotland were always stated to have the highest prevalence (300 per 100,000), but newer studies in Canada have shown that some provinces have numbers that high or higher.
Low risk areas include Central and South America, most of Asia and all of Africa. The risk is low in Native Americans. MS is virtually unknown in one group of Eskimos (don't remember which one) and in Hungarian Gypsies. Both these groups have little inter-racial mixing which adds to the belief that genetics play a role.
Location
In the northern hemisphere there is a very strong gradient of increasing MS cases as you move farther from the equator. I think one of our Australian members reported a study showing the same increase in MS numbers for the southern hemisphere, or at least for Australia and New Zealand. This does not hold universally true. Japan which has the same general lattitude as Europe, has a much lower risk of MS.
Migration
Then the studies of the effect of migration throw changes into the picture. there is a consistent finding that if a person moves before the age of puberty, they take on the risk of the new location. So, if a person moves from a very high prevalence location in Canada to Southern California at age 10, their risk drops from the 200 -300 per 100,000 people to So Cal's lower risk of about 60. Again, there are exceptions. A second-generation Japanese in the US retains about the same lower risk as their ancestors.
The reverse seems true also. Moving at a young age from a lower risk area to a higher risk area appears to raise a person's risk to the new, higer risk area.
Some areas and racial groups are seeing an increase in MS over the last several decades. This suggests the introduction of another triggering factor such as an infection.
Differences in how the MS shows up
Asians tend to have a higher incidence of Optico-spinal MS (Neuromyelitis Optica), but over time that balance is changing.
Diet
There has been no evidence that diet plays a large role in the development of MS. that was an assumption of people like Dr. Swank, but larger, but performed studies have shown that he was mistaken.
Gene studies
MS is associated with an increase in certain tissue types. That is a whole other answer. There have been dozens of specific genes associated with MS and there is not yet one nor one combination that could reliably be a test for the disease nor for the likelihood of developing MS.
So, that is part of the answer about what causes MS and who gets it.
Quix