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RAB3GAP1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

RAB3GAP1 gene

The RAB3GAP1 gene provides instructions for creating a protein essential for regulating cellular vesicle trafficking and hormone release.

Normal Function

The RAB3GAP1 gene provides instructions for making a protein that helps regulate the activity of specialized proteins called GTPases, which control a variety of functions in cells. To perform its function, the RAB3GAP1 protein interacts with another protein called RAB3GAP2 to form the RAB3GAP complex.

GTPases act as molecular switches, turning on when bound to GTP and off when bound to GDP. The RAB3GAP complex activates a GTPase known as RAB18 by exchanging GTP for the attached GDP. When active, RAB18 is involved in vesicle trafficking, which moves proteins and other molecules within cells. RAB18 also regulates the storage and release of fats by lipid droplets, plays a role in autophagy, and helps organize the endoplasmic reticulum.

Additionally, the RAB3GAP complex is thought to inactivate another GTPase known as RAB3 by stimulating a reaction that converts GTP to GDP. RAB3 plays a role in the release of hormones and neurotransmitters from cells.

Health Conditions Related to Genetic Changes

RAB18 deficiency

More than 60 RAB3GAP1 gene mutations have been found to cause RAB18 deficiency, resulting in conditions that affect the eyes, brain, and reproductive system:

  • Warburg micro syndrome: Located at the severe end of the spectrum, this condition is caused by mutations that prevent the production of any RAB3GAP1 protein or eliminate its function.
  • Martsolf syndrome: Located at the mild end of the spectrum, this occurs when a small amount of functional RAB3GAP1 protein is produced.

The reduction or loss of this protein impairs the formation or function of the RAB3GAP complex, leading to a deficiency in RAB18 activity. It is currently unclear why the loss of RAB18 function leads to the specific eye problems, brain abnormalities, and other features of these conditions.

Coloboma

MedlinePlus Genetics provides information about Coloboma.

Keratoconus

MedlinePlus Genetics provides information about Keratoconus.

Other Names for This Gene

  • KIAA0066
  • P130
  • RAB3 GTPase activating protein subunit 1 (catalytic)
  • RAB3 GTPase-activating protein 130 kDa subunit
  • rab3 GTPase-activating protein catalytic subunit isoform 1
  • rab3 GTPase-activating protein catalytic subunit isoform 2
  • rab3-GAP p130
  • RAB3GAP
  • RAB3GAP130
  • WARBM1

Genomic Location

The RAB3GAP1 gene is found on chromosome 2.

Frequently Asked Questions

Both conditions are caused by mutations in the RAB3GAP1 gene but differ in severity based on the level of protein function remaining. Warburg micro syndrome is the severe end of the spectrum, caused by mutations that result in little to no functional RAB3GAP1 protein, leading to significant intellectual disability, severe eye abnormalities, and growth delays. Martsolf syndrome is milder, occurring when some functional protein is still produced, resulting in less severe intellectual disability and physical features, though eye issues and short stature are still present. How does a RAB3GAP1 mutation affect eye health, and what specific treatments are available for vision problems?::Mutations in RAB3GAP1 often lead to microphthalmia (small eyes), cataracts, and retinal dystrophy, which can cause significant vision loss. Treatment is supportive and focuses on managing specific eye conditions, such as surgical removal of cataracts to improve vision if the retina is functional. Regular ophthalmologic exams are critical to monitor for changes in eye structure and function, and low-vision specialists can provide assistive devices and therapies to help individuals maximize their remaining visual capabilities. Can RAB3GAP1-related conditions be detected before birth, and what does prenatal testing involve?::Yes, if a family has a known RAB3GAP1 mutation, prenatal testing is possible. This can be done through chorionic villus sampling (CVS) or amniocentesis, where a sample of fetal tissue or amniotic fluid is analyzed for the specific genetic variant. Ultrasound can sometimes detect physical signs like small eyes or growth restrictions, but genetic testing is required for a definitive diagnosis. Early detection allows parents to prepare for medical care and connect with support resources.
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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