DSG1 and acquired polycythemia vera: PV is mediated by pathogenic IgG autoantibodies targeting desmosomal cadherins—primarily desmoglein 3 (Dsg3) and, in some cases, desmoglein 1 (Dsg1)—leading to disruption of keratinocyte adhesion (acantholysis) and intraepithelial blister formation [12].