Notwithstanding the fact that medical science has been grappling with MS for over 100 years, knowledge about MS causes remains somewhat murky. The causes of multiple sclerosis are not as straightforward to identify as, say, the causes of Down’s syndrome or of Lyme disease. The former is identified in a straightforward manner- as a chromosomal condition that results from the presence of all or part of an additional copy of chromosome 21 in the cells. The latter is a bacterial infection that is typically spread by tick bites.

As for multiple sclerosis, it is not possible to point at one single factor, genetic or environmental, and to claim that that is the definitive cause of the condition in a particular individual. Rather, one can suggest that the individual is genetically predisposed towards developing MS by pointing to changes in a particular area of chromosome 6. One can then talk about …