DLX gene family

Genes in the DLX family encode homeodomain transcription factors related to the Drosophila distal-less (Dll) gene. The family has been related to a number of developmental features such as jaws and limbs. The family seems to be well preserved across species. As DLX/Dll are involved in limb development in most of the major phyla, including vertebrates, it has been suggested that Dll was involved in appendage growth in an early bilaterial ancestor.

Six members of the family are found in human and mice, numbered DLX1 to DLX6. They form two-gene clusters (bigene clusters) with each other. There are DLX1-DLX2, DLX3-DLX4, DLX5-DLX6 clusters in vertebrates, linked to Hox gene clusters HOXD, HOXB, and HOXA respectively.

In higher fishes like the zebrafish, there are two additional DLX genes, dlx2b (dlx5) and dlx4a (dlx8). These additional genes are not linked with each other, or any other DLX gene. All six other genes remain in bigene clusters.

DLX4, DLX7, DLX8 and DLX9 are the same gene in vertebrates. They are named differently because every time the same gene was found, the researchers thought they had found a new gene.