Based on the clinical presentation and the specificity of the anti-desmoglein (Dsg) autoantibodies, pemphigus is classified into two main forms, pemphigus vulgaris (PV), with autoantibodies targeting Dsg3, and in some cases also Dsg1, and pemphigus foliaceus (PF), with autoantibodies targeting Dsg1 (1). This evidence concerns the gene DSG1 and acquired polycythemia vera.