In the PV groups, anti-Dsg3 IgG antibodies were significantly higher in patients with mucocutaneous than oral PV (135.9 vs. 95.3, p = 0.0003), whereas the average value of anti-Dsg1 IgG antibodies was significantly lower in patients with oral PV than in patients with muco-cutaneous PV (8.6 vs. 111.6, p < 0.0001t). Here, DSG1 is linked to acquired polycythemia vera.