Normal Function
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.
More About This Health ConditionOther 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
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
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. Erratum In: Am J Hum Genet. 2011 May 13;88(5):678. Bond, Frances F [corrected to Bond, Frances C]. 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
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