SOX9

The SOX9 gene provides instructions for making a protein that plays a critical role during embryonic development. The SOX9 protein is especially important for the development of the skeleton and reproductive system. This protein attaches (binds) to specific regions of DNA and regulates the activity of other genes. On the basis of this action, the SOX9 protein is called a transcription factor.

campomelic dysplasia - caused by mutations in the SOX9 gene

More than 45 mutations involving the SOX9 gene have been found to cause campomelic dysplasia, a disorder that is often life-threatening in the newborn period. Most cases of campomelic dysplasia are caused by mutations within the SOX9 gene. These mutations prevent the production of the SOX9 protein or result in a protein with impaired ability to function as a transcription factor. About 5 percent of cases are caused by chromosome abnormalities that occur around the SOX9 gene. These chromosome abnormalities disrupt regions of DNA that normally regulate the activity of the SOX9 gene. All of these genetic changes prevent the SOX9 protein from properly controlling the genes essential for normal development of the skeleton, reproductive system, and other parts of the body. Abnormal development of these structures causes the signs and symptoms of campomelic dysplasia.

Individuals with milder forms of campomelic dysplasia are more likely to have chromosome abnormalities around the SOX9 gene than mutations within the gene.

other disorders - associated with the SOX9 gene

Chromosome abnormalities that occur around the SOX9 gene may also cause some cases of Pierre-Robin sequence. Individuals with this condition have an opening in the roof of the mouth (a cleft palate), a tongue that is placed further back than normal (glossoptosis), and a small lower jaw (micrognathia). These cases of Pierre-Robin sequence are described as isolated or nonsyndromic because they occur without other signs and symptoms. Research suggests that some chromosome abnormalities near the SOX9 gene disrupt the regulation of this gene only in certain parts of the body. These particular chromosome abnormalities likely prevent the SOX9 protein from properly controlling the development of facial structures, which leads to isolated Pierre-Robin sequence.