EXT2

The EXT2 gene provides instructions for producing a protein called exostosin-2. This protein is found in a cell structure called the Golgi apparatus, which modifies newly produced enzymes and other proteins. In the Golgi apparatus, exostosin-2 attaches (binds) to another protein, exostosin-1, to form a complex that modifies a protein called heparan sulfate so it can be used in the body. Heparan sulfate is involved in regulating a variety of body processes including the formation of blood vessels (angiogenesis) and blood clotting. It also has a role in the spreading (metastasis) of cancer cells.

hereditary multiple exostoses - caused by mutations in the EXT2 gene

More than 90 mutations in the EXT2 gene have been identified in people with hereditary multiple exostoses type 2. Most of these mutations prevent any functional exostosin-2 protein from being made, and are called "loss of function" mutations. The loss of exostosin-2 protein function prevents it from forming a complex with the exostosin-1 protein and modifying heparan sulfate. It is unclear how this impairment leads to the signs and symptoms of hereditary multiple exostoses.

other disorders - caused by mutations in the EXT2 gene

A mutation resulting in the deletion of the EXT2 gene causes a condition called proximal 11p deletion syndrome. In addition to multiple exostoses, people with this condition have enlarged openings in two bones at the top of the back of the skull (parietal foramina). Signs and symptoms seen in some people with proximal 11p deletion syndrome include intellectual disability, a difference in the appearance between the right and left sides of the face (facial asymmetry), vision problems, skeletal abnormalities, and heart defects.

Proximal 11p deletion syndrome (sometimes referred to as Potocki-Shaffer syndrome) is often described as a contiguous gene deletion syndrome because it results from the loss of several genes that are close together near the center (proximal region) of chromosome 11, on the short (p) arm.

Researchers have determined that the loss of the EXT2 gene is responsible for the multiple exostoses seen in people with this condition. The loss of another gene, ALX4, in the same region of chromosome 11 may help explain the defects in skull development. Additional genes in the deleted region likely contribute to the varied features of proximal 11p deletion syndrome.