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The Goosecoid (Gsc) homeodomain protein is a transcription factor is expressed in all vertebrates. Gsc promotes the formation of Spemann’s Organizer. This organizer prevents BMP-4 from inducing the ectoderm in the future head region of the embryo to become epidermis; it instead allows the future head region to form neural folds, which will eventually turn into the brain and spinal cord. For normal anterior development to occur, Spemann’s organizer cannot express the Xwnt-8 or BMP-4 transcription factors. Gsc directly represses the expression of Xwnt-8 while indirectly repressing BMP-4 (Yao and Kessler, 2001). The inhibition of Xwnt-8 and BMP-4 ensures that normal anterior development, promoted by Spemann’s organizer, can occur. The expression of Gsc occurs twice in development, first during gastrulation and second during organogenesis (Yamada et al. 1995). Gsc is found in high concentrations in the dorsal mesoderm and endoderm during gastrulation. The later expression of Gsc is confined to the head region. In the Xenopus, cells that express Gsc become the pharyngeal endoderm, the head mesoderm, and the notocord (De Robertis et al. 1992). Mutations in the Gsc gene can lead to specific phenotypes resulting from the second expression of the Gsc gene during organogenesis. Mice knock-out models of the gene express defects in the tongue, nasal cavity, nasal pits, inner ear, and external auditory meatus (Yamada et al. 1997). Neonate mice born with this mutation die within 24 hours due to complication with breathing and sucking milk, resulting from the craniofacial abnormalities caused by the mutation. Mutations to the Gsc gene in humans can lead to a condition known as SAMS syndrome, characterized by short stature, auditory canal atresia, mandibular hypoplasia, and skeletal abnormalities. (Parry et al. 1993, Lemire et al. 1998)