MS Active Source
positive living with MS
This content is intended for Medical professional use only
Please select your professional status below if you are a medical professional or click here to return to the msactivesource.co.uk website if you are not.
Clicking on the relevant title certifies that you are a healthcare professional accessing in your capacity as a healthcare professional.
MS Nurse...click here
Nurse...click here
Doctor...click here
MS Specialist...click here
You are leaving MS Active Source
You are leaving www.msactivesource.co.uk, a web site of Biogen Idec UK & Ireland. Links to all outside web sites are provided as a resource to our visitors. Biogen Idec accepts no responsibility for the content of other web sites.
Who gets MS
Despite much research, it is still unknown why some people develop MS or what the triggers are which stimulate the autoimmune reactions that lead to the characteristic pathological changes and symptoms associated with MS. However, various factors which increase the risk of developing MS have been identified. These fall into two categories: genetic factors and environmental factors (see figure 1).
Figure 1. Factors which increase the risk of developing MS
Genetic factors
Various studies have shown that family members of patients with MS have a higher risk of developing MS compared with the general population, while for identical twins; there is a 1 in 3 risk of developing MS for a twin whose sibling has MS (ref m6). This data, together with the fact that MS is very rare in certain populations (e.g. Inuits) suggests that there are genetic factors contribute to the development of MS. Indeed a recent study has identified particular forms of two genes which strongly predict the risk of developing MS (ref m7). However, the fact that the risk of developing MS in the second identical twin when one has MS is only 1 in 3 indicates that other factors also contribute to the risk of developing MS.
Please click here for our eFeature on MS and families, which offers further information, support and links.
Environmental factors
Investigation of the prevalence of MS in different regions has found that the risk of MS increases with distance from the equator (ref m1). From this and other data it has been suggested that the risk of MS is related to exposure to sunlight, (ref m8) possibly due to the impact of sunlight on vitamin D levels (ref m9). In particular, the risk appears to be related to where a person lived for the first 15 years of life (ref m1).
It has been suggested that particular viral or bacterial infections may contribute to the risk
of developing MS. An association between
Epstein-Barr Virus (EBV) and MS has
been observed in some people,
(ref m10) while another study found evidence of chronic
infection with the bacterium '
Chlamydia Pneumoniae' in patients
with MS
(ref m11).
Other factors which have been associated with an increased risk of MS are severe stress
(ref m12) and smoking
(ref m13).
Prevalence
Although it is unclear why certain people develop MS and what factors affect the risk of MS, it
is well established that the prevalence of MS varies widely with geographical region. The
prevalence is highest in Europe, North America, and Australasia where 1 in 1000 individuals
develops MS and is lower in the Arabian Peninsula, Asia and South America. In other regions such as
sub-Saharan Africa, MS is rare
(ref m1). (figure 2)
Figure 2. Incidence of MS by regions
Did you know?
Multiple Sclerosis is a disease of unknown origin that affects the central nervous system.
Quick Links
Supported by
This website is intended for use in Great Britain and Northern Ireland.
Please click here for msactivesource.ie
Page last updated: 22 Jun 2010
| This site complies to the HONcode standard for trustworthy health information: verify here. |