What is MS?

Multiple Sclerosis (MS) is an inflammatory disease of the Central Nervous System (CNS) (the brain and spinal cord). Predominantly, it is a disease of the "white matter" tissue. The white matter is made up of nerve fibers which are responsible for transmitting communication signals both internally within the CNS and between the CNS and the nerves supplying rest of the body.

In people affected by MS, patches of damage called plaques or lesions appear in seemingly random areas of the CNS white matter. At the site of a lesion, a nerve insulating material, called myelin, is lost.    More about demyelination

Occurrence

There is considerable variation in the occurrence of MS around the world. This has been ascribed to environmental factors, like exposure to viruses or ionising radiation, or to genetic factors. One constant, though, is that prevalence rates are higher in places closer to the poles compared to places closer to the equator. In certain localities such as the border areas of Scotland the incidence may be as high as 203 per 100,000.

Most experts agree that this unusual relationship between geographic location and MS suggests that an environmental factor is partly responsible for causing the disease.

MS is more common within some population groups than it is within others. Studies done in Scotland and Canada have shown that MS has a particularly high prevalence within peoples of European descent - British and Scandinavian especially. Within peoples of British descent, it is particularly common in those of Celtic descent.

While genetics may make a person more susceptible to contracting MS, there has been no evidence found to show a direct genetic inheritance link.    More about who gets MS.

MS is not inherited in the same way that diabetes and other diseases are inherited. A family history of the disease also puts people at risk for MS, although the risk for someone inheriting all the genetic factors contributing to MS is only about 2% to 4%.