The diagnosis of PV is based on four major criteria: clinical presentation, histopathology, DIF of a perilesional skin or mucosal biopsy and serological detection of autoantibodies against epithelial cell surface using indirect immunofluorescence (IIF) and/or enzyme-linked immunosorbent assay (ELISA Dsg1 and Dsg3) [5]. The gene discussed is DSG3; the disease is acquired polycythemia vera.