This is first suggested by the fact that most sera (63.3%) collected at the onset of pemphigus or in patients with persistent disease activity under treatment (75%) contained two or more anti-DSG3 IgG subclasses, while on the contrary, most sera (64.3%) from patients in CR contained only one anti-DSG3 IgG subclass (corresponding to IgG4 in all but one case). The gene discussed is DSG3; the disease is pemphigus.