MAGEB1 and systemic lupus erythematosus: Eight genes are encoded at the Xp21.2 SLE risk locus (rs887369; P = 3.34 × 10−7; OR = 1.43): four Melanoma Antigen B (MAGEB) family genes (MAGEB1-4), NR0B1 encoding the DAX1 nuclear receptor, GK (glycerol kinase), TAB3 (TGF-beta activated kinase 1 and MAP3K7 binding protein 3) and CXorf21 (Fig. 1a; Supplementary Table 4).