Multiple Sclerosis: risk factors

The causes of Multiple Sclerosis (MS) are not understood. The disease appears to be more common in northern-most and southern-most latitudes (Kurtzke (1997)) and there is evidence that it is more common in the northern than the southern parts of the UK (Kurtzke (1997), Forbes and Swingler (1999)). There is some evidence of temporal and geographical clusters (Kurtzke (1997), Donnan et al (2005)). These findings have been interpreted as suggesting an environmental cause, such as an infectious agent. However, they might also be compatible with the geographical distribution of particular genetic risk factors. The finding of an increased risk of MS in the families of MS patients might support this latter view. Others have suggested that MS may result from the combination of an environmental trigger and a susceptible genotype. The disease has recently been reported to be more common among children born in winter months (Willer et al (2005)).