Jaw transformation with gain of symmetry after Dlx5/Dlx6 inactivation: mirror of the past?

Genesis. 2002 Dec;34(4):221-7. doi: 10.1002/gene.10156.


In modern vertebrates upper and lower jaws are morphologically different. Both develop from the mandibular arch, which is colonized mostly by Hox-free neural crest cells. Here we show that simultaneous inactivation of the murine homeobox genes Dlx5 and Dlx6 results in the transformation of the lower jaw into an upper jaw and in symmetry of the snout. This is the first homeotic-like transformation found in this Hox-free region after gene inactivation. A suggestive parallel comes from the paleontological record, which shows that in primitive vertebrates both jaws are essentially mirror images of each other. Our finding supports the notion that Dlx genes are homeotic genes associated with morphological novelty in the vertebrate lineage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Biological Evolution
  • Gene Deletion
  • Gene Dosage
  • Gene Expression Regulation, Developmental
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism*
  • Jaw / embryology*
  • Jaw / metabolism
  • Jaw / pathology
  • Mandible / abnormalities
  • Mandible / metabolism
  • Mice
  • Morphogenesis


  • Dlx5 protein, mouse
  • Dlx6 protein, mouse
  • Homeodomain Proteins