"Best to you all; Dave"
http://www.mayo.edu/research/RWeb/news_&_events.html
Is Multiple Sclerosis Caused by an Infection or Genes? What the Research
Shows...
Is multiple sclerosis caused by an infectious agent in the environment?
Or is it inherited?
Writing in a recent issu of Mayo Clinic Proceedings, Mayo researchers
say that studies support both theories.
>Some of the findings which support an environmental cause include:
prevalence of MS varies with geography, generally increasing with
distance from the equator
offspring of people who move often have prevalence rates of MS similar
to those in their new residence and different from their place of origin
clusters and epidemics of MS have been reported
MS is not uniformly distributed among identical twins, which would be
expected if the disease were purely genetic.
>Proponents of a genetic cause cite some of the following findings:
MS is primarily a disease of Caucasians, and certain ethnic groups
(especially Northern Europeans) are more vulnerable than others
First degree relatives of patients with MS have a 20-40 times greater
risk of having MS than the general population
MS has a 6 - 10 times higher occurrence rate in identical twins than in
fraternal twins.
The authors conclude that accumulated evidence suggests an environmental
influence occurring on a background of genetic susceptibility. They say,
"there is little evidence for a single or unique environmental cause of
MS."