The study by Lenz et al1 heralds the arrival of the era of molecular diagnosis of immunobullous diseases. These investigators translated advances in basic molecular biology into advances in clinical immunology tests that are likely to be used by practicing dermatologists. Indirect immunofluorescence (IIF) has been used successfully since the 1960s to identify autoantibodies to the pemphigus antigen, desmoglein 3 (Dsg3). However, the Dsg3 required for this test is expensive because it must be extracted from keratinocytes. The authors not only successfully produced Dsg3 using recombinant techniques, but they also used the Dsg3 as a substrate for a specific enzyme-linked immunosorbent assay (ELISA) other than IIF.