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RAB18 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

RAB18 gene

The RAB18 gene encodes a GTPase that regulates vesicle trafficking, lipid droplet dynamics, autophagy, and endoplasmic reticulum organization; loss‑of‑function mutations lead to Warburg micro syndrome.

Overview

The RAB18 gene provides instructions for producing the RAB18 protein, which functions as a GTPase. Often referred to as molecular switches, GTPases can be turned on and off. They are turned on (active) when they are attached (bound) to a molecule called GTP and are turned off (inactive) when they are bound to another molecule called GDP. When active, RAB18 is involved in a process called vesicle trafficking, which moves proteins and other molecules within cells in sac‑like structures called vesicles. RAB18 regulates the movement of substances between compartments in cells and the storage and release of fats (lipids) by structures called lipid droplets. The protein also appears to play a role in a process called autophagy, which helps clear unneeded materials from cells. RAB18 is important for the organization of a cell structure called the endoplasmic reticulum, which is involved in protein processing and transport.

Health Conditions Related to Genetic Changes

RAB18 deficiency

At least five mutations in the RAB18 gene have been found to cause Warburg micro syndrome, which is the most severe of the disorders caused by RAB18 deficiency. Warburg micro syndrome is characterized by multiple eye abnormalities, vision impairment, severe intellectual disability, and a reduction of the hormones that direct sexual development (hypogonadotropic hypogonadism).

The RAB18 gene mutations that cause Warburg micro syndrome eliminate the function of the RAB18 protein. It is unclear how a shortage (deficiency) of RAB18 activity leads to eye problems, brain abnormalities, and other features of Warburg micro syndrome.

Other Names for This Gene

  • RAB18 small GTPase
  • RAB18LI1
  • ras‑related protein Rab‑18 isoform 1
  • ras‑related protein Rab‑18 isoform 2
  • ras‑related protein Rab‑18 isoform 3
  • ras‑related protein Rab‑18 isoform 4
  • ras‑related protein Rab‑18 isoform 5
  • WARBM3

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

  • Tests of RAB18

Scientific Articles on PubMed

  • PubMed

Catalog of Genes and Diseases from OMIM

  • RAS‑ASSOCIATED PROTEIN RAB18; RAB18

Gene and Variant Databases

  • NCBI Gene
  • ClinVar

References

  • Bem D, Yoshimura S, Nunes‑Bastos R, Bond FC, Kurian MA, Rahman F, Handley MT, Hadzhiev Y, Masood I, Straatman‑Iwanowska AA, Cullinane AR, McNeill A, Pasha SS, Kirby GA, Foster K, Ahmed Z, Morton JE, Williams D, Graham JM, Dobyns WB, Burglen L, Ainsworth JR, Gissen P, Muller F, Maher ER, Barr FA, Aligianis IA. Loss‑of‑function mutations in RAB18 cause Warburg micro syndrome. Am J Hum Genet. 2011 Apr 8;88(4):499-507. doi: 10.1016/j.ajhg.2011.03.012. Citation on PubMed or Free article on PubMed Central
  • Feldmann A, Bekbulat F, Huesmann H, Ulbrich S, Tatzelt J, Behl C, Kern A. The RAB GTPase RAB18 modulates macroautophagy and proteostasis. Biochem Biophys Res Commun. 2017 May 6;486(3):738-743. doi: 10.1016/j.bbrc.2017.03.112. Epub 2017 Mar 22. Citation on PubMed
  • Gerondopoulos A, Bastos RN, Yoshimura S, Anderson R, Carpanini S, Aligianis I, Handley MT, Barr FA. Rab18 and a Rab18 GEF complex are required for normal ER structure. J Cell Biol. 2014 Jun 9;205(5):707-20. doi: 10.1083/jcb.201403026. Epub 2014 Jun 2. Citation on PubMed or Free article on PubMed Central
  • Handley MT, Carpanini SM, Mali GR, Sidjanin DJ, Aligianis IA, Jackson IJ, FitzPatrick DR. Warburg Micro syndrome is caused by RAB18 deficiency or dysregulation. Open Biol. 2015 Jun;5(6):150047. doi: 10.1098/rsob.150047. Citation on PubMed or Free article on PubMed Central

Genomic Location

The RAB18 gene is found on chromosome 10.

MEDICAL ENCYCLOPEDIA

  • Genes
  • Genetics

Understanding Genetics

  • What is DNA?
  • What is a gene?
  • What is a gene variant and how do variants occur?

Frequently Asked Questions

Diagnosis typically begins with a pediatrician or geneticist evaluating the child's physical features, such as microcephaly (small head size), eye abnormalities, and delayed motor skills. A definitive diagnosis is confirmed through genetic testing, specifically sequencing the RAB18 gene to identify loss-of-function mutations. Because the condition is rare, clinicians may also use chromosomal microarray or whole-exome sequencing if initial targeted testing is negative. :: What are the specific eye abnormalities associated with RAB18 mutations?::Children with Warburg micro syndrome often present with microphthalmia (abnormally small eyes) or anophthalmia (absence of eyes). Other common ocular features include coloboma, which is a gap in the structure of the eye, and cataracts. These eye conditions frequently lead to significant vision impairment and require specialized ophthalmological care and low-vision support. :: Is Warburg micro syndrome inherited, and what are the chances of it recurring in a family?::Warburg micro syndrome is inherited in an autosomal recessive pattern, meaning a person must inherit two mutated copies of the RAB18 gene, one from each parent, to develop the condition. Parents who are carriers usually do not show symptoms. If both parents are carriers, there is a 25% chance with each pregnancy that the child will be affected, a 50% chance the child will be a carrier, and a 25% chance the child will inherit no mutated copies. :: What are the long-term management strategies for the hormonal and neurological aspects of the condition?::Management is multidisciplinary and focuses on supportive care. For hypogonadotropic hypogonadism, which affects sexual development, hormone replacement therapy may be required during puberty. Neurological management involves early intervention services, including physical, occupational, and speech therapy, to maximize developmental potential. Regular monitoring by neurologists and endocrinologists is essential to address evolving needs.
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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