Sequence-specific DNA-binding transcription factor that binds palindromic sequences within promoters and may activate or repress the transcription of a subset of genes. Most probably regulates the expression of genes involved in the development of mesenchyme-derived craniofacial structures (By similarity). May therefore play a role in beak development and regulate beak shape (PubMed:25686609). Binds DNA as a homodimer; required for transcriptional activation. The OAR motif may negatively regulate DNA-binding and therefore transcriptional activity. It is found in the C-terminal transactivation domain that stimulates transcription. Variations in ALX1 may play a key role in beak morphology. Two haplotypes for this gene are observed within the different species of finches. The B haplotype is almost exclusively found in individuals with a blunt beak while the P haplotype is neatly associated with individuals having a peaked beak. There are 335 fixed differences aggregated in the vicinity of the gene between B and P haplotypes including 2 missense mutations at positions 112 and 211. In the medium ground finch, Geospiza fortis which exhibits high intraspecies variation in beak shape, both haplotypes have been reported but a significant association with beak shape has also been observed. Finch beak morphology observed on the Galapagos Islands was used by Charles Darwin to formulate his theory of evolution. Belongs to the paired homeobox family. The makings of a face - Issue 173 of November 2015