ALX homeobox protein 1 is a protein that in humans is encoded by the ALX1 gene.[5][6][7]
The specific function of this gene has yet to be determined in humans; however, in rodents, it is necessary for survival of the forebrain mesenchyme and may also be involved in development of the cervix. Mutations in the mouse gene lead to neural tube defects such as acrania and meroanencephaly.[7]
In Burmese cats, especially the lineage known as Contemporary Burmese, a deletion of four aminoacids in ALX1 is common. When heterozygous, the mutation causes brachycephaly; when homozygous it causes a fatal head malformation known as Burmese head defect.[8]
In Darwin's finches, inhabiting the Galapagos islands, ALX1 has been linked to the diversity of beak shapes.[9]