DSG3 and acquired polycythemia vera: Dsg1 can compensate for loss of Dsg3 function in the epidermis [4]; accordingly, in PV patients and mouse models, Dsg3 antibodies alone predominantly induce clinical blisters in hair follicles and mucous membranes whereas combined Dsg3 and Dsg1 antibodies concomitantly evoke epidermal blisters [3,4,6,7,8].