CALR and systemic lupus erythematosus: Systemic Lupus Erythematosus (SLE) is the archetypal autoimmune connective tissue disease, characterized by the production of multiple auto-antibodies [anti-nuclear antibodies (ANA), anti-double stranded DNA (dsDNA), anti-Sm/RNP, anti-Ro/La] and the consumption of complement (1, 2).