['Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are two blistering skin diseases mediated by antibodies to desmoglein 3 (Dsg3) and/or Dsg1. Phenotypic transition from PV to PF is rarely reported.', 'To determine the immune response to extracellular (EC) domains of Dsgs during this transition.', 'We report two PV patients who subsequently developed a PF phenotype. To map the conformational epitopes in these cases, we examined the reactivity of the sera of two patients by immunoprecipitation-immunoblotting analysis, using five Dsg1/Dsg3 domain-swapped molecules on a backbone of Dsg2.', 'Reactivity exclusively with the EC1 domain of Dsg1 was maintained in both PV and PF stages. No reactivity to Dsg3 in the PF stage was found in patient 1. Various changes in immunoreactivity to Dsg3 were found and the EC1 and EC2 domains of Dsg3 reacted weakly to serum taken at remission and PF stages in patient 2.'] Are antibodies to the amino-terminal domain of desmoglein 1 retained during transition from pemphigus vulgaris to pemphigus foliaceus?