CRB1

The CRB1 gene provides instructions for making a protein that plays an essential role in normal vision. This protein is found in the brain and the retina, which is the specialized tissue at the back of the eye that detects light and color.

In the retina, the CRB1 protein appears to be critical for the normal development of light-sensing cells called photoreceptors. Studies suggest that this protein is part of a group (complex) of proteins that help determine the structure and orientation of photoreceptors. The CRB1 protein may also be involved in forming connections between different types of cells in the retina.

Leber congenital amaurosis - caused by mutations in the CRB1 gene

More than 50 mutations in the CRB1 gene have been found to cause Leber congenital amaurosis. Mutations in this gene account for 9 to 13 percent of all cases of this condition.

Most of the CRB1 gene mutations responsible for Leber congenital amaurosis lead to an abnormally short, nonfunctional version of the CRB1 protein or significantly reduce the amount of this protein produced in cells. A shortage of the CRB1 protein disrupts the early development of the retina. The retina becomes unusually thick and does not develop the normal layered structure. These changes cause severe visual impairment beginning very early in life.

other disorders - caused by mutations in the CRB1 gene

At least 35 mutations in the CRB1 gene have been identified in people with another eye disorder called retinitis pigmentosa. This condition is characterized by progressive vision loss caused by the gradual degeneration of photoreceptors in the retina. CRB1 gene mutations cause several uncommon forms of retinitis pigmentosa that are differentiated by their specific retinal changes.

The CRB1 gene mutations that cause retinitis pigmentosa lead to a partial or total loss of CRB1 protein function. A shortage of normal CRB1 protein impairs the development of the retina and leads to the progressive degeneration of photoreceptors.

It is unclear why some people with CRB1 gene mutations have severe, early visual impairment associated with Leber congenital amaurosis, and other people experience more gradual vision loss and other eye problems associated with retinitis pigmentosa. Researchers suspect that other genetic factors may modify the effects of CRB1 gene mutations to influence the severity of these conditions.

Genetics Home Reference provides information about retinitis pigmentosa, which is also associated with changes in the CRB1 gene.