We hypothesized that elevated circulating levels of HMGB1 and decreased circulating levels of sRAGE are also present in primary APS (pAPS) patients, and both HMGB1 and sRAGE have a role in the differentiation between APA-positive SLE patients with and without thrombotic events. The gene discussed is HMGB1; the disease is systemic lupus erythematosus.