Clinical ACR criteria, positive ANA, and a probable SLE-CSQ score, alongside SCF and BLyS, consistently differentiated unaffected relatives vs. those who developed ILE (Figures 6A–C, middle panel), while IL-10, SCF, and ACR criteria best differentiated ILE vs. SLE across the cohorts (Figures 6A–C, right panel). Here, KITLG is linked to systemic lupus erythematosus.