COL5A1

The COL5A1 gene provides instructions for making a component of collagen. Collagens form a family of proteins that strengthen and support many tissues in the body, including skin, ligaments, bones, tendons, muscles, and the space between cells and tissues called the extracellular matrix. The COL5A1 gene produces a component of type V collagen, called the pro-alpha1(V) chain. Three of these chains combine to make a molecule of type V procollagen. Alternatively, two of these chains can also combine with one pro-alpha2(V) chain (produced by the COL5A2 gene) to form type V procollagen. These triple-stranded rope-like procollagen molecules must be processed by enzymes outside the cell. Once these molecules are processed, they arrange themselves into long, thin fibrils that cross-link to one another in the spaces around cells. The cross-links result in the formation of very strong, mature type V collagen fibers. Type V collagen also plays a role in assembling other types of collagen into fibrils within many connective tissues and is essential for the formation of normal type I collagen fibrils.

Ehlers-Danlos syndrome - caused by mutations in the COL5A1 gene

More than 50 percent of cases of classical Ehlers-Danlos syndrome are caused by mutations in the COL5A1 gene. Many of these mutations lead to a nonfunctional or absent pro-alpha1(V) chain. As a result, type V collagen fibrils in the skin and other tissues cannot be assembled correctly. The fibrils are disorganized and larger than usual. Researchers have not determined precisely how these changes in collagen structure cause the signs and symptoms of classical Ehlers-Danlos syndrome.