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CRB1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CRB1 gene

The CRB1 gene provides essential instructions for the development and maintenance of light-sensing cells in the retina.

Normal Function

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

In the retina, the CRB1 protein is 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 arrangement of photoreceptors within the retina and the position of various components within photoreceptors (cell polarity). The CRB1 protein may also be involved in forming connections between different types of cells in the retina.

Health Conditions Related to Genetic Changes

Leber congenital amaurosis

Pathogenic variants in the CRB1 gene can cause Leber congenital amaurosis type 8. Leber congenital amaurosis is a group of eye disorders that affect the retina. People with this condition typically have severe vision loss that begins during the first year of life. Pathogenic variants in the CRB1 gene account for approximately 10 percent of all cases of Leber congenital amaurosis.

Most of the pathogenic variants in the CRB1 gene associated with this condition cause cells to make a version of the protein that does not function properly. The altered protein disrupts the organization and early development of the retina. As a result, the retina becomes unusually thick and does not develop the normal layered structure needed to process visual information.

Cone-rod dystrophy

MedlinePlus Genetics provides information about Cone-rod dystrophy.

Retinitis pigmentosa

MedlinePlus Genetics provides information about Retinitis pigmentosa.

Other disorders

Some people with CRB1-associated retinal diseases can develop the following features:

  • Round, coin-shaped pigmented deposits in the retina.
  • Para-arteriolar sparing, a condition in which certain tissue around the retinal blood vessels remains healthy while other parts of the retina break down.
  • Small calcium deposits in the optic nerve (optic nerve drusen).

In rare cases, pathogenic variants in the CRB1 gene can also cause pigmented paravenous retinochoroidal atrophy (PPRCA), which is characterized by the degeneration (atrophy) of the retina and its supporting layer of blood vessels and connective tissue (choroid).

Other Names for This Gene

  • Crumbs cell polarity complex component 1
  • Crumbs homolog 1
  • LCA8

Frequently Asked Questions

Pathogenic CRB1 mutations are inherited in an autosomal recessive manner: both parents must carry one copy of a disease‑causing variant. Each subsequent pregnancy carries a 25 % chance of an affected child, a 50 % chance of a carrier, and a 25 % chance of an unaffected, non‑carrier child. Carrier testing for relatives and pre‑implantation genetic diagnosis (PGD) are options for families who wish to reduce recurrence risk.
Newborns or infants who do not make eye contact, have absent or severely reduced visual tracking, exhibit nystagmus (rapid eye movements), or have a markedly reduced response to light should be evaluated promptly. These findings often signal severe retinal dysfunction that can be caused by CRB1 mutations.
Testing usually involves a blood draw or saliva sample sent to a certified genetics laboratory. The lab will perform targeted sequencing of the CRB1 gene or a broader retinal dystrophy panel. Prior to testing, a genetic counselor can review family history, discuss potential results (pathogenic, likely pathogenic, variant of uncertain significance), and explain implications for you and relatives.
Currently, there is no cure, but management focuses on maximizing remaining vision (low‑vision aids, orientation and mobility training) and monitoring for complications such as cataracts. Ongoing clinical trials are investigating gene‑replacement therapy and neuroprotective agents for CRB1‑associated Leber congenital amaurosis and retinitis pigmentosa; eligibility depends on age, disease stage, and specific mutation.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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