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A genetic basis for familial aggregation in multiple sclerosis. Canadian Collaborative Study Group
G C Ebers1, A D Sadovnick, N J Risch
1Department of Clinical Neurological Sciences, University of Western Ontario, London, Canada.
Nature
|September 14, 1995
Summary
Familial aggregation of multiple sclerosis (MS) is primarily genetic. This study found no evidence of shared environmental factors contributing to MS risk among relatives.
Area of Science:
- Neuroimmunology
- Human Genetics
- Epidemiology
Background:
- Autoimmune disorders like multiple sclerosis (MS) are complex traits.
- Familial aggregation and geographical distribution suggest genetic and environmental factors.
- Previous studies lacked consensus on the role of infectious agents or shared environments.
Purpose of the Study:
- To investigate the contribution of genetic versus environmental factors to MS familial aggregation.
- To differentiate between genetic heritability and shared environmental influences in MS.
Main Methods:
- Screened a population-based sample of 15,000 individuals with MS.
- Utilized standardized questionnaires to identify adopted individuals and/or adopted relatives.
- Compared MS frequency in non-biological relatives living with index cases to population prevalence.
Main Results:
- MS frequency among first-degree non-biological relatives was not higher than general population rates.
- Familial aggregation of MS was significantly less pronounced in non-biological relatives compared to biological relatives.
- No detectable effect of shared environment on MS occurrence was observed.
Conclusions:
- Familial aggregation of multiple sclerosis is predominantly determined by genetic factors.
- Shared environmental influences do not appear to play a significant role in the familial clustering of MS.
- This study provides strong evidence for genetic heritability in multiple sclerosis etiology.