CYP2D6 and systemic lupus erythematosus: To determine the prevalence of selected single nucleotide polymorphisms (rs1080985, rs28624811, rs1065852, rs28371725, and rs1135840) in cytochromeP450 2D6 (CYP2D6) gene among Saudi systemic lupus erythematosus (SLE) patients and to investigate the association between the genetic variants and clinical features of SLE.