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GNAT2 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GNAT2 gene

The GNAT2 gene provides instructions for making a protein in cone cells that is essential for daylight and color vision.

Normal Function

The GNAT2 gene provides instructions for making one part (called the cone-specific alpha subunit) of a protein called transducin. This protein is found in light-detecting (photoreceptor) cells called cones, which are located in a specialized tissue at the back of the eye known as the retina. Cones provide vision in bright light (daylight vision), including color vision. Other photoreceptor cells, called rods, provide vision in low light (night vision).

Transducin plays an essential role in transmitting visual signals from photoreceptor cells in the retina to the brain through a process called phototransduction. Photoreceptors contain special pigments (called photopigments) that absorb light. The photopigments activate transducin, which triggers a series of chemical reactions within the cell. These reactions alter the cell's electrical charge, ultimately generating a signal that is interpreted by the brain as vision.

Health Conditions Related to Genetic Changes

Achromatopsia

Variants in the GNAT2 gene are associated with achromatopsia, a condition that affects color vision and light sensitivity.

Other Names for This Gene

  • ACHM4
  • cone-type transducin alpha subunit
  • GNAT2_HUMAN
  • GNATC
  • guanine nucleotide binding protein (G protein), alpha transducing activity polypeptide 2
  • guanine nucleotide binding protein, alpha transducing activity polypeptide 2
  • transducin alpha-2 chain
  • transducin, cone-specific, alpha polypeptide

Frequently Asked Questions

Diagnosis begins with a detailed visual acuity and color vision assessment, followed by electroretinography (ERG) to evaluate cone function. Genetic confirmation is obtained through targeted sequencing panels that include GNAT2, or through whole-exome sequencing if a broader genetic workup is needed. A positive result confirms the diagnosis and informs family counseling.
Patients with GNAT2 mutations often notice difficulty distinguishing colors, especially reds and greens, and may report extreme sensitivity to bright light or glare. If a child or adult experiences sudden loss of color perception or complains of pain or visual distortion when exposed to bright daylight, these are red flags that warrant a comprehensive ophthalmologic evaluation.
While there is no cure, management focuses on reducing light sensitivity and improving daily visual function. This includes prescription of high‑contrast or tinted lenses, use of wide‑spectrum sunglasses, and adaptive lighting strategies. Low‑vision aids such as magnifiers, specialized lighting, and assistive technology can also help maintain independence.
Research is underway to develop gene replacement therapies that deliver a functional copy of GNAT2 to cone cells. Early animal studies show promise, but clinical trials in humans are still in the planning stages. Patients should discuss participation in clinical research with their ophthalmologist and genetic counselor.
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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