Article Text

Multiple sclerosis in stepsiblings: recurrence risk and ascertainment
  1. D A Dyment1,
  2. I M L Yee2,
  3. G C Ebers1,
  4. A D Sadovnick2,3,
  5. for the Canadian Collaborative Study Group
  1. 1The Wellcome Trust Center for Human Genetics and the Department of Clinical Neurology, University of Oxford, Oxford, UK
  2. 2Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
  3. 3Faculty of Medicine, Division of Neurology, University of British Columbia, Vancouver, BC, Canada
  1. Correspondence to:
 Professor A D Sadovnick
 University of British Columbia, G-920, Detwiller Pavillion, Vancouver Coastal Health Authority, UBC Hospital, 2211 Westbrook Mall, Vancouver, BC, V6T 2B5 Canada; sadovnik{at}


Reports implicating specific transmissible agents in multiple sclerosis (MS) susceptibility continue to appear. We therefore re-evaluated MS risk in 687 stepsiblings of 19 746 MS index cases. We found the risk of MS to be indistinguishable from that of the general population after diagnostic verification. These results are coherent with studies of adopted children, half siblings and conjugals, showing no risk attributable to the familial microenvironment. This family based genetic epidemiological approach found no trace of transmissibility other than genetic from one affected individual to another in the high prevalence area of Canada. This adds to existing data showing that the action of environment in influencing MS risk is operative at a population level.

  • MS, multiple sclerosis
  • multiple sclerosis susceptibility
  • population-based study
  • stepsiblings

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  • Canadian Collaborative Study Group: J J-F Oger, D W Paty, S A Hashimoto, V Devonshire, J Hooge, J P Smythe, T Traboulsee (Vancouver), L Metz (Calgary), S Warren (Edmonton), W Hader (Saskatoon), R Nelson, M Freedman (Ottawa), D Brunet (Kingston), J Paulseth (Hamilton), G Rice, M Kremenchutzky (London), P O’Connor, T Gray, M Hohol (Toronto), P Duquette, Y Lapierre (Hôpital Notre Dame and Montreal Neurological Institute, Montreal), J-P Bouchard (Quebec City), T J Murray, V Bhan, C Maxner (Halifax), W Pryse-Phillips, M Stefanelli (St Johns)

  • Competing interests: none

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