Polyautoimmunity in Sjögren Syndrome.

Polyautoimmunity is defined as the presence of more than one well-defined autoimmune disease (AD) in a single patient. Polyautoimmunity is a frequent condition in Sjögren syndrome (SS) and follows a grouping pattern. The most frequent ADs observed in SS are autoimmune thyroid disease, rheumatoid arthritis, and systemic lupus erythematosus. Main factors associated with polyautoimmunity in SS are tobacco smoking and some genetic variants. The study of polyautoimmunity provides important clues for elucidating the common mechanisms of autoimmne diseases (ie, the autoimmune tautology).