RNPC3 and systemic lupus erythematosus: Primary Sjögren syndrome (pSS) is a systemic autoimmune disease, which shares a number of clinical, serological and genetic features with systemic lupus erythematosus (SLE).1 One of the features of this disease is the high prevalence of autoantibodies to the Ro and La components of a ribonuclear protein (RNP) complex.