The level of anti-S1/RBD protein IgG antibodies in patients with AIIRD (median [IQR], 8.8 [2.2–17.3]) and SLE (median [IQR], 9.6 [2.4–20.4]) was comparable to that in the control group (median [IQR], 7.2 [3.1–14.2]), p > 0.05. Here, PSMD1 is linked to systemic lupus erythematosus.