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Family studies of multiple sclerosis

University of British Columbia

The overall objective of the Canadian Collaborative Project on the Genetic Susceptibility to Multiple Sclerosis (CCPGSMS) is to elucidate the pathogenesis of Multiple Sclerosis (MS). The aims of this thesis, as part of the CCPGSMS, were to 1) confirm the involvement of genetics in the susceptibility to MS 2) to examine the effects of the shared familial environment on MS risk and 3) to determine if a maternal effect can increase the risk to MS. Fourteen thousand nine hundred and ninety active Multiple Sclerosis (MS) clinic patients were screened as part of the CCPGSMS between the dates of Sept., 1994 and May,1996. From this group, 203 twin pairs, (80 monozygotic and 123 dizygotic), were identified. The proband-wise monozygotic twin concordance rate was 28.25% (SE. 5.84%) and the dizygotic twin concordance rate was 5.61% (S.E. 2.45%). The risk to the non-twin sibs of an index case was estimated at 2.49% (S.E. 0.74%) which was not significantly different than the dizygotic twin risk estimate, 0.05<p<0.10. This confirms the results of previous studies, and supports a strong genetic contribution to MS susceptibility. Five hundred and forty-five MS patients were identified with adoptive parents, and/or adopted sibs, and/or adopted children. The total adoptive first degree relatives of MS patients was 1185. Only one of these individuals had clinically definite MS. This was significantly different than the 25.2 affected individuals expected if the shared familial environment was important to the familial aggregation of MS, p=2.98 X 10"10. This supports the hypothesis that familial aggregation of M S is due primarily to genetics and not to the sharing of the familial environment. Nine hundred and thirty-six index cases were identified that had at least one half-sibling. There was no significant difference in the risk estimate between maternal half-siblings, 1.47% (S.E. 0.42%) and paternal half-siblings, 1.31% (S.E. 0.46%), 0.75<p<0.90. This argues against the contribution of a significant maternal effect to M S risk.

Thesis/Dissertation

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2009-03-09

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http://hdl.handle.net/2429/5782

Medical Genetics

University of British Columbia

UBCV

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