In addition to their positive anti–TIF1-γ antibody status, 3 patients without cancer each had a single specificity identified (anti-CCAR1, -NVL2, and -NACC1), 1 patient had 2 specificities identified (anti-RCC1 and -GATD1), and 1 patient (patient 111) had 5 antibody specificities identified (anti-TBL1XR1, -KDM1A, -IMMT, -SOX5, and -C1Z1). Here, RCC1 is linked to cancer.