Serum levels of IFN-γ in patients with IgG4-RD (2.23 ± 1.56 pg/mL) were comparable to those in pSS patients (3.20 ± 3.15 pg/mL; P = 0.493), and both were significantly higher than in HC (1.02 ± 0.81 pg/mL; Figure 5F). This evidence concerns the gene IFNG and peeling skin syndrome.