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MYO5B gene

myosin VB

Normal Function

The MYO5B gene provides instructions for making a protein called myosin Vb. This protein is one of a group of proteins with similar structures called myosins, which are involved in cell movement and the transport of materials within and between cells. Myosin Vb helps to determine the position of various components within cells (cell polarity). Myosin Vb also plays a role in moving components from the cell membrane to the interior of the cell for recycling.

Health Conditions Related to Genetic Changes

Microvillus inclusion disease

More than 40 mutations in the MYO5B gene have been found to cause microvillus inclusion disease. This condition is characterized by chronic, life-threatening diarrhea beginning in infancy. The MYO5B gene mutations that cause this condition result in a decrease or absence of myosin Vb function. In cells that line the small intestine (enterocytes), a lack of myosin Vb function changes the cell polarity. As a result, enterocytes cannot properly form structures called microvilli, which normally project like small fingers from the surface of the cells and absorb nutrients and fluids from food as it passes through the intestine. Inside affected enterocytes, small clumps of abnormal microvilli mix with misplaced digestive proteins to form microvillus inclusions, which contribute to the dysfunction of enterocytes. Disorganized enterocytes with poorly formed microvilli reduce the intestine's ability to take in nutrients and fluids. The inability to absorb nutrients and fluids during digestion leads to severe diarrhea, malnutrition, and dehydration in individuals with microvillus inclusion disease.

More About This Health Condition

Other Names for This Gene

  • KIAA1119
  • MYO5B variant protein
  • myosin-Vb
  • unconventional myosin-Vb

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Knowles BC, Roland JT, Krishnan M, Tyska MJ, Lapierre LA, Dickman PS, Goldenring JR, Shub MD. Myosin Vb uncoupling from RAB8A and RAB11A elicits microvillus inclusion disease. J Clin Invest. 2014 Jul;124(7):2947-62. doi: 10.1172/JCI71651. Epub 2014 Jun 2. Citation on PubMed or Free article on PubMed Central
  • Thoeni CE, Vogel GF, Tancevski I, Geley S, Lechner S, Pfaller K, Hess MW, Muller T, Janecke AR, Avitzur Y, Muise A, Cutz E, Huber LA. Microvillus inclusion disease: loss of Myosin vb disrupts intracellular traffic and cell polarity. Traffic. 2014 Jan;15(1):22-42. doi: 10.1111/tra.12131. Epub 2013 Nov 19. Citation on PubMed
  • van der Velde KJ, Dhekne HS, Swertz MA, Sirigu S, Ropars V, Vinke PC, Rengaw T, van den Akker PC, Rings EH, Houdusse A, van Ijzendoorn SC. An overview and online registry of microvillus inclusion disease patients and their MYO5B mutations. Hum Mutat. 2013 Dec;34(12):1597-605. doi: 10.1002/humu.22440. Epub 2013 Oct 16. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.