Risk of multiple sclerosis in relatives of 357 French multiple sclerosis patients.

The empiric recurrence risk of multiple sclerosis (MS) of relatives of Fren ch MS patients is not known. Using a standardized interview, we collected t he family histories of 357 consecutive patients followed at our MS clinic: adequate information was obtained on 4784 relatives up to the third degree. Thirty-five patients (9.8 p.100) had a relative with MS. The risk-curve fo r relatives was the same as in other studies conducted with a similar metho dology in Canada, England and Flanders, but the crude overall MS recurrence risk for relatives was lower in France. The genetic burden of MS may be lo wer in France than in areas of higher MS prevalence.