DSG1 and acquired polycythemia vera: In mucocutaneous PV (mcPV), pathological autoimmunity targets desmoglein 3 (DSG3; abundantly expressed in basal and parabasal layers of the epidermis and the mucosa) and desmoglein 1 (DSG1; abundantly expressed in upper layers of the epidermis but scantly expressed in the mucosa), whereas in mucosal dominant PV (mdPV)—DSG3 is classically targeted (9).