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GNAQ gene

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

GNAQ gene

The GNAQ gene provides instructions for a protein subunit that regulates blood vessel development, and its mutation is linked to vascular disorders and certain eye cancers.

Normal Function

The GNAQ gene provides instructions for making the guanine nucleotide-binding protein G(q) subunit alpha (Gαq). This protein is part of a trimeric G protein complex that binds to G protein-coupled receptors. When activated by binding to a molecule called GTP, the Gαq protein separates from the complex to trigger signaling pathways that regulate blood vessel development and function. It is inactivated when it converts GTP to GDP.

Health Conditions Related to Genetic Changes

Sturge-Weber syndrome

A specific somatic mutation in the GNAQ gene (Arg183Gln or R183Q) causes Sturge-Weber syndrome. This mutation prevents the Gαq protein from converting GTP to GDP, leaving the protein in a permanently active state. This constant signaling disrupts blood vessel development, leading to:

  • A red or pink port-wine birthmark
  • Brain abnormalities
  • Increased pressure in the eye (glaucoma)

Other disorders

The R183Q mutation can also cause isolated port-wine birthmarks without the associated brain or eye abnormalities. Additionally, somatic mutations in the GNAQ gene are found in uveal melanoma, a cancer of the middle layer of the eye. In these cases, the overactive protein leads to excessive signaling that contributes to the overgrowth of cells and tumor formation.

Frequently Asked Questions

Research is ongoing; currently, no FDA‑approved drugs specifically target mutant Gαq. However, clinical trials are exploring MEK inhibitors and other downstream pathway blockers that may mitigate the effects of overactive Gαq signaling.
skin biopsy of the birthmark followed by DNA sequencing can detect the common R183Q mutation in the GNAQ gene. If the mutation is present, it suggests a higher likelihood of associated Sturge‑Weber syndrome features.
Children should have regular ophthalmologic evaluations, including intraocular pressure checks, optic nerve imaging, and visual field testing, ideally every 6 to 12 months, to monitor for glaucoma or other ocular complications.
Somatic GNAQ mutations are found in about 80–90% of uveal melanomas, but the risk for an individual with a germline or mosaic mutation is still low. Nonetheless, regular eye exams and prompt evaluation of any new eye lesions are advised.
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.