Autoimmune disease in first-degree relatives of patients with multiple sclerosis - A UK survey

Previous studies examining an association with other autoimmune diseases ha ve suggested the existence of a generalized autoimmune diathesis in patient s with multiple sclerosis. We investigated the prevalence of autoimmune dis ease in first-degree relatives of probands with multiple sclerosis using a case-control method. The results show an excess of autoimmune disease withi n these families, but no significant association was seen with nonautoimmun e diseases. The higher risk in multiplex than simplex families suggests an effect of genetic loading. While the increase in risk applies to each autoi mmune disease, autoimmune thyroid disease (and Graves' disease in particula r) contributes disproportionately to the excess risk, There was no increase in autoimmune disease within patients with multiple sclerosis themselves w hen compared with the index controls or population data, We conclude that a utoimmune disease is more common in first-degree relatives of patients with multiple sclerosis and hypothesize that common genetic susceptibility fact ors for autoimmunity co-exist with additional disease specific genetic or e nvironmental factors, which determine clinical phenotype in the individual.