EDN1 and systemic sclerosis: To evaluate potential of serum ET-1 as a biomarker for SLE, a validation cohort including 102 SLE patients and 252 non-SLE diseases patients was discussed further (90 RA, 95 osteoarthritis (OA), 55 sjogren syndrome (SS), 38 anlylosing spondylitis (AS), 17 SSc).