A comprehensive diagnosis of pemphigus is based on four criteria: (a) clinical presentation, (b) histopathologic examination of a lesional biopsy, (c) direct immunofluorescence (DIF) examination of a perilesional skin or mucosal biopsy, and (d) serological detection of autoantibodies against epithelial cell surfaces by indirect immunofluorescence (IIF) and/or enzyme-linked immunosorbent assay (ELISA Dsg1 and Dsg3). The gene discussed is DSG1; the disease is pemphigus.