CALR and Arthritis: B.II.1 was a 47-year-old Chinese Han female diagnosed with systemic lupus erythematosus (SLE) featuring ANAs, anti-double-stranded DNA, anti-Ro (Sjögren's disease (SjD)-related antigen A (SSA)) and antiphospholipid antibodies, arthritis, proteinuria (urinary protein more than 500 g per 24 h), and hypergammaglobulinemia of IgG, IgG1, IgG4 and IgE, with an IgG4:IgG ratio of 0.14 (Fig. 1f and Supplementary Table 1).