Crouzon syndrome is an autosomal dominant genetic disorder known as a branchial arch syndrome. Specifically, this syndrome affects the first branchial (or pharyngeal) arch, which is the precursor of the maxilla and mandible. Since the branchial arches are important developmental features in a growing embryo, disturbances in their development create lasting and widespread effects. This syndrome is named after Octave Crouzon, a French physician who first described this disorder. He noted the affected patients were a mother and her daughter, implying a genetic basis.