We recently demonstrated strong genetic linkage between the type VII collagen gene (COL7A1) and both the dominant and recessive forms of dystrophic epidermolysis bullosa. In this study, we searched for mutations in dominant dystrophic epidermolysis bullosa using polymerase chain reaction amplification of segments of COL7A1, followed by heteroduplex analysis. Examination of the polymerase chain reaction corresponding to exon 73 revealed a heteroduplex resulting from a G-to-A transition at nucleotide 6127 in the triple-helical domain of COL7A1, which converted a glycine residue to an arginine (G2043R). The dominant dystrophic epidermolysis bullosa phenotype in this family probably arose because of a dominant negative effect of this mutation in COL7A1, resulting in the formation of structurally abnormal anchoring fibrils.