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RHO gene

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

RHO gene

The RHO gene provides instructions for making rhodopsin, a protein essential for vision in low-light conditions.

Normal Function

The RHO gene provides instructions for making a protein called rhodopsin. This protein is found in the light-sensitive tissue at the back of the eye, known as the retina. The retina contains two types of specialized light receptor cells: rods and cones.

  • Cones: Responsible for color vision and vision in bright light.
  • Rods: Responsible for vision in low light.

Rhodopsin is found in rods, where it plays a critical role in low-light vision. The protein binds to a molecule called 11-cis retinal, a form of vitamin A. When light hits this molecule, it activates rhodopsin, triggering a series of chemical reactions that create electrical signals transmitted to the brain for interpretation.

Health Conditions Related to Genetic Changes

Autosomal dominant congenital stationary night blindness

Pathogenic variants in the RHO gene can cause autosomal dominant congenital stationary night blindness, characterized by a stable loss of vision in low light. Unlike retinitis pigmentosa, this condition does not affect daytime vision. Because it is autosomal dominant, a variant in only one copy of the gene is sufficient to cause the disorder.

These variants cause cells to produce a version of rhodopsin that activates even in the absence of light. This disrupts rod cell signaling, leading to misinterpreted signals sent to the brain.

Retinitis pigmentosa

Pathogenic variants in the RHO gene can also cause retinitis pigmentosa, a condition characterized by progressive vision loss. While most cases are inherited in an autosomal dominant manner, rare cases are autosomal recessive, requiring variants in both copies of the gene.

  • These variants typically lead to an altered version of rhodopsin that interferes with essential cell functions, causing rod cells to self-destruct.
  • The loss of these rods leads to progressive night blindness.
  • The condition is also associated with a gradual loss of cone cells, though the exact mechanism for this secondary destruction is still being studied.

Other disorders

Pathogenic variants in the RHO gene can cause retinitis punctata albescens, which is characterized by childhood-onset night blindness. Individuals with this condition typically exhibit white dots, or flecks, in the retina during eye exams, which indicate cell breakdown. The altered rhodopsin impairs rod cell function, eventually leading to the impairment of neighboring cells and vision loss.

Other Names for This Gene

  • CSNBAD1
  • OPN2
  • opsin
  • RP4

Frequently Asked Questions

utosomal dominant congenital stationary night blindness caused by RHO variants requires only one altered copy of the gene to manifest, whereas most RHO-related retinitis pigmentosa cases are also autosomal dominant but rare autosomal recessive forms exist. In the recessive form, an individual must inherit two pathogenic variants, one from each parent, to develop the condition. This distinction is critical for genetic counseling, as the risk of passing the trait to offspring differs significantly between dominant and recessive inheritance models.
The progression depends entirely on the specific diagnosis. Autosomal dominant congenital stationary night blindness is non-progressive, meaning the difficulty seeing in low light remains stable throughout life and does not affect daytime vision. In contrast, RHO-related retinitis pigmentosa is a progressive disorder where vision loss typically worsens over decades, often starting with night blindness and peripheral vision loss before potentially affecting central vision in later stages.
While no diet can reverse genetic mutations, maintaining adequate vitamin A levels is crucial because rhodopsin requires 11-cis retinal, a form of vitamin A, to function. Patients should consult a clinician before taking high-dose vitamin A supplements, as excessive intake can be toxic. Additionally, using high-contrast lighting, magnifiers, and maximizing remaining peripheral vision through eccentric viewing techniques can improve daily functional independence, particularly for those with retinitis pigmentosa.
In autosomal dominant conditions, which account for the majority of RHO-related retinitis pigmentosa, there is no such thing as an asymptomatic carrier; if a person has the pathogenic variant, they will typically develop symptoms, although the age of onset and severity can vary. However, in the rare autosomal recessive form, parents can be carriers with one copy of the variant and remain completely healthy and symptom-free, only passing the risk to their children if both parents carry a variant.
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.