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CNGB3 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CNGB3 gene

The CNGB3 gene provides instructions for a protein component of channels in the eye that are essential for color vision and vision in bright light.

Overview

The CNGB3 gene provides instructions for making the beta subunit of the cyclic nucleotide-gated (CNG) channel. These channels are found exclusively in cones, the photoreceptor cells in the eye responsible for color vision and daytime vision.

Normal Function

CNG channels are openings in the cell membrane that transport positively charged ions into cells. In low light, these channels remain open, allowing ions to flow in. When light enters the eye, the channels close, stopping the flow of ions. This change in ion transport alters the cone's electrical charge, generating a signal that is sent to the brain. This process of translating light into an electrical signal is known as phototransduction.

Health Conditions Related to Genetic Changes

Achromatopsia

Variants in the CNGB3 gene are a leading cause of achromatopsia, a retinal disorder characterized by a partial or total loss of color vision.

  • Prevalence: Approximately 40 to 50 percent of people with achromatopsia have a variant in the CNGB3 gene.
  • Mechanism: Most variants result in a non-functional beta subunit, which impairs the function of CNG channels and the cones' ability to respond to light.
  • Specific Populations: A specific variant (Ser435Phe) is common among Pingelapese islanders in Micronesia, leading to complete achromatopsia.

Cone-rod dystrophy

This condition affects the function of cones, leading to vision problems such as increased light sensitivity and reduced color vision that worsen over time.

Other disorders

Variants in the CNGB3 gene have been identified in individuals with progressive cone dystrophy. While this condition also affects cone function, it typically manifests in childhood or adolescence.

Other Names for This Gene

  • ACHM3
  • achromatopsia (rod monochromacy) 3
  • cyclic nucleotide gated channel beta 3

Frequently Asked Questions

Yes. High‑contrast glasses, tinted or amber lenses that reduce glare, and custom‑designed contact lenses can lessen photophobia and improve visual comfort. Low‑vision devices such as magnifiers, electronic reading aids, and adaptive computer software also help maximize residual vision for reading and navigation.
fter a thorough ophthalmic exam that reveals absent color vision, photophobia, and reduced visual acuity, the next step is molecular testing. A targeted retinal dystrophy gene panel or whole‑exome sequencing that includes CNGB3 is performed to detect pathogenic biallelic variants. Confirmation may be supplemented by electrophysiology (ERG) showing absent cone responses.
Several phase I/II clinical trials are evaluating adeno‑associated virus (AAV) vectors delivering a normal CNGB3 copy directly into the subretinal space. Early results show safety and modest improvements in visual acuity and light sensitivity. Patients may consider enrollment if they meet age and disease‑stage criteria; discuss options with a retinal specialist or a clinical‑trial coordinator.
CNGB3‑related achromatopsia follows an autosomal recessive pattern. Each parent carries one mutated allele, giving each sibling 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 and genetic counseling are recommended for family planning.
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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