PAX3 and branchiooculofacial syndrome: Haploinsufficiency of other craniofacial TFs often causes syndromes comprising characteristic facial features (for example, PAX3 in Waardenburg, TWIST1 in Saethre–Chotzen, TFAP2A in branchiooculofacial syndromes), but similar to SOX9, these TFs bind to and presumably regulate thousands of REs (and perhaps hundreds of genes).