What causes Multiple Sclerosis?

Just like other autoimmune diseases, the exact cause of multiple sclerosis is unknown, but is linked to genetic and environmental factors. Genetic risk factors include being a woman and having genes that encode a specific type of immune molecule.

Environmental risk factors might include infections as well as vitamin D deficiency, which is an interesting one because it might help explain why the rates of multiple sclerosis are higher at the northern and southern poles compared to the equator where there's a lot more sunlight. Together these genetic and environmental influences might lead to the body not killing off immune cells that target myelin.