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[Familial multiple sclerosis: a study of six families].

INTRODUCTION
Multiple sclerosis (MS) is a demyelinating disorder of the CNS, of autoimmune pathology and unknown aetiology. Several theories regarding its aetiology have been suggested, although none seems to be completely convincing. Genetically predisposed persons are affected, therefore groups of MS are seen in certain families.


OBJECTIVES
To describe the family links, type of illness and evolution of 12 patients from six families with two or more members diagnosed as having MS, and to evaluate any differences from the other cases recorded in our data base.


PATIENTS AND METHODS
We studied 12 patients diagnosed on the criteria of Poser, and with at least one first or second degree relation with MS. We compared clinical data, form of presentation and course with 127 patients recorded in the data base.


RESULTS
We describe six families: two homozygotic twins, two families in which transmission was from father to child and three families with first degree cousins affected. We found no clinical variation in the presentation, number of attacks or evolution, as compared with the other patients. Nor was there homogeneity between the familial forms of MS.


CONCLUSIONS
Familial forms make up approximately 10% of the series. We do not have any data available for early diagnosis nor for prognostic significance of familial MS.