September 30, 2003
Source: Proceedings of the National Academy of Sciences
A new study confirms earlier work that suggests environment and genetics may both play a role in the development of multiple sclerosis.
Multiple sclerosis is one of the most common neurological diseases among young adults, leading to a progressive loss of neural function. The condition affects about one in 1,000 people, and women are twice as likely as men to have the disease. Many studies have indicated both genetic and environmental causes of the condition, and twin studies have shown the disease is more likely to occur in identical rather than fraternal twins. However, researchers now say these past studies may have been affected by other factors, such as the possibility that being born a twin increases the risk of getting MS and overall rates of MS in the community.
These researchers collected data on about 75 percent of all the twins in Canada with MS and compared it to general population data. Results showed no difference between the rate among twins with MS and people in general, suggesting being a twin does not increase the risk of MS. The frequency of a gene related to MS was also the same in twins with MS and non-twins with MS. When compared to fraternal twin pairs, female identical twins were at greater risk of having MS if their twin also had the disease. When fraternal twins were compared to non-twin siblings, the risk of MS was higher for a twin if his twin had MS, suggesting a role for gestational factors.
The authors conclude genetic factors do play a role in the development
of MS, particularly among females, but other factors, such as premature
birth, may also be involved in some cases.
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