Familial multiple sclerosis and association with other autoimmune diseases.

Objectives: Autoimmune diseases (AID) follow a complex, probably polygenic, pattern of inheritance and often cluster in families of patients with multiple sclerosis (MS). Our objective was to analyze family patterns and characteristics in families including more than one patient with MS.

Materials and Methods: We analyzed personal and family history of neurological, systemic, and autoimmune diseases in 84 MS patients from 40 different families. Families were classified in two groups: families with cases of MS in at least two different generations (15 families) and families in which cases of MS belonged to only one generation (25 families).

Results: The two previously established groups presented different clinical patterns and frequency of association with another AID. In one group, the second generation displayed a higher annual relapse rate than the first generation, higher frequency of progressive forms of MS, and more patients with another AID in addition to MS. Relapsing-remitting forms of MS (RRMS) were more frequent in the other group.

Conclusions: Families that include more than one MS patient may show two distinct patterns. This finding seems important for the compression and analysis of genetic information on MS.