TRIM21 and autoimmune disease: Sjögren’s syndrome is an autoimmune disorder characterized by lymphocyte infiltration of the lacrimal, salivary, conjunctival, and pharyngeal mucosal glands, with variable involvement of extra glandular tissue and autoantibody production (mostly directed against ribonucleoproteins TRIM21/Ro52/SS-A, Ro60, and La/SS-B.