MSX1

The MSX1 gene provides instructions for making a protein that regulates the activity of other genes. The MSX1 gene is part of a larger family of homeobox genes, which act during early development to control the formation of many body structures. Specifically, this gene is critical for the normal development of the teeth and other structures in the mouth. It may also be important for development of the fingernails and toenails.

Wolf-Hirschhorn syndrome - associated with the MSX1 gene

The MSX1 gene is often deleted in people with Wolf-Hirschhorn syndrome, even though it is located outside the region of chromosome 4 that is typically deleted in people with this condition. A loss of the MSX1 gene probably disrupts the regulation of several other genes, particularly genes involved in the development of the mouth and teeth. Researchers believe that a deletion of the MSX1 gene disrupts the formation of oral structures in early development, leading to missing teeth and other dental abnormalities. A loss of the MSX1 gene probably also causes an opening in the roof of the mouth (cleft palate) and/or a split in the upper lip (cleft lip) in some people with Wolf-Hirschhorn syndrome.

other disorders - associated with the MSX1 gene

Changes in the MSX1 gene are also associated with other abnormalities of mouth and tooth development. For example, changes in this gene contribute to some cases of cleft lip and/or cleft palate in people who do not have Wolf-Hirschhorn syndrome. These genetic variations (polymorphisms) have been associated with isolated cleft lip and cleft palate in several different populations worldwide. MSX1 polymorphisms appear to be one of many genetic and environmental factors that play a role in oral clefting.

At least six MSX1 mutations are responsible for oligodontia, a condition in which multiple teeth fail to develop. Some individuals with MSX1 mutations have a combination of oligodontia and cleft lip and/or cleft palate. Mutations in the MSX1 gene likely reduce the amount of functional MSX1 protein within cells, which disrupts the early development of structures in the mouth.

Another mutation in the MSX1 gene has been found to cause Witkop syndrome (also known as tooth-and-nail syndrome) in one large family. This rare condition is characterized by a variable number of missing teeth and abnormalities of the fingernails and toenails. The MSX1 mutation responsible for Witkop syndrome, written as Ser202Ter or S202X, leads to the production of an abnormally short, nonfunctional version of the MSX1 protein. A loss of this protein disrupts the formation of the teeth and nails during early development.