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RDH5 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

RDH5 gene

The RDH5 gene provides instructions for an enzyme essential for the visual cycle and maintaining normal vision, particularly in low-light conditions.

Normal Function

The RDH5 gene provides instructions for making an enzyme called 11-cis retinol dehydrogenase 5, which is necessary for normal vision, especially in low-light conditions (night vision). This enzyme is found in a thin layer of cells at the back of the eye called the retinal pigment epithelium (RPE). This cell layer supports and nourishes the retina, which is the light-sensitive tissue in the inner lining of the back of the eye.

11-cis retinol dehydrogenase 5 is involved in a multi-step process called the visual cycle, by which light entering the eye is converted into electrical signals. An integral operation of the visual cycle is the recycling of a molecule called 11-cis retinal, a form of vitamin A. The enzyme converts 11-cis retinol to 11-cis retinal. In light-sensing cells known as photoreceptors, 11-cis retinal combines with a protein called an opsin to form a photosensitive pigment. When light hits this pigment, it triggers chemical reactions that create electrical signals. The enzyme then helps convert all-trans retinal back to 11-cis retinal so the cycle can begin again.

Health Conditions Related to Genetic Changes

Fundus albipunctatus

At least 48 mutations in the RDH5 gene have been found to cause fundus albipunctatus, a condition characterized by impaired night vision and whitish-yellow flecks in the retina. The mutations are thought to reduce or eliminate the function of the 11-cis retinol dehydrogenase 5 enzyme, resulting in a shortage of 11-cis retinal. Without this molecule, electrical signals integral for vision are not stimulated. Researchers speculate that impairment of this enzyme also leads to the accumulation of 11-cis retinol and related molecules, forming the characteristic flecks.

Other Names for This Gene

  • 11-cis RDH
  • 11-cis retinol dehydrogenase precursor
  • 11-cis RoDH
  • 9-cis retinol dehydrogenase
  • 9-cis-retinol specific dehydrogenase
  • 9cRDH
  • HSD17B9
  • RDH1
  • retinol dehydrogenase 1
  • retinol dehydrogenase 5 (11-cis and 9-cis)
  • retinol dehydrogenase 5 (11-cis/9-cis)
  • SDR9C5
  • short chain dehydrogenase/reductase family 9C member 5

Frequently Asked Questions

Patients benefit from allowing longer dark‑adaptation periods before activities requiring night vision, using high‑contrast lighting, and avoiding bright glare. Wearing sunglasses during daylight reduces phototoxic stress on the retina. Regular ophthalmic follow‑up is important to monitor for secondary retinal changes.
There is no cure, but patients often experience gradual improvement in night vision after prolonged dark adaptation (up to 30 minutes). Some clinicians trial high‑dose vitamin A or 9‑cis‑retinoid supplements, but evidence is limited and they must be used under ophthalmologic supervision because excess vitamin A can be toxic.
Fundus albipunctatus caused by RDH5 mutations follows an autosomal‑recessive inheritance pattern. Both parents are typically carriers, giving each child a 25 % chance of being affected, a 50 % chance of being an asymptomatic carrier, and a 25 % chance of inheriting two normal alleles. Carrier testing for siblings can clarify their risk.
Diagnosis typically involves a full ophthalmic exam with fundus photography (showing characteristic white flecks), electroretinography (ERG) demonstrating delayed dark‑adapted responses, and molecular genetic testing of the RDH5 gene. No special preparation is needed for imaging, but for ERG you may be asked to avoid bright light exposure for several hours beforehand to maximize the test’s sensitivity.
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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