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G6PC gene

glucose-6-phosphatase catalytic subunit

Normal Function

The G6PC gene provides instructions for making an enzyme called glucose 6-phosphatase. This enzyme is found on the membrane of the endoplasmic reticulum, which is a structure inside cells that is involved in protein processing and transport. Glucose 6-phosphatase works together with the glucose 6-phosphate translocase protein (produced from the SLC37A4 gene) to break down a type of sugar molecule called glucose 6-phosphate. The breakdown of this molecule produces the simple sugar glucose, which is the primary source of energy for most cells in the body. The glucose 6-phosphatase enzyme is expressed (active) in the liver, kidneys, and intestines, and is the main regulator of glucose production in the liver.

Health Conditions Related to Genetic Changes

Glycogen storage disease type I

At least 85 mutations in the G6PC gene have been found to cause glycogen storage disease type Ia (GSDIa). Most of these mutations change single protein building blocks (amino acids) in the glucose 6-phosphatase enzyme. Some specific mutations are seen more frequently in certain ethnic or racial groups. Mutations in the G6PC gene impair the function of the glucose 6-phosphatase enzyme. When this enzyme is not functioning normally, glucose 6-phosphate is not broken down and glucose is not produced. Glucose 6-phosphate that is not broken down to glucose is converted to fat and glycogen, a complex sugar that is stored within cells. Too much fat and glycogen stored within a cell can be toxic. This buildup damages organs and tissues throughout the body, particularly the liver and kidneys, leading to the signs and symptoms of GSDIa.

More About This Health Condition

Other Names for This Gene

  • G-6-Pase
  • G6Pase
  • G6Pase-alpha
  • glucose-6-phosphatase
  • glucose-6-phosphatase alpha
  • glucose-6-phosphatase, catalytic subunit

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


  • Chou JY, Mansfield BC. Mutations in the glucose-6-phosphatase-alpha (G6PC) gene that cause type Ia glycogen storage disease. Hum Mutat. 2008 Jul;29(7):921-30. doi: 10.1002/humu.20772. Citation on PubMed or Free article on PubMed Central
  • Hutton JC, O'Brien RM. Glucose-6-phosphatase catalytic subunit gene family. J Biol Chem. 2009 Oct 23;284(43):29241-5. doi: 10.1074/jbc.R109.025544. Epub 2009 Aug 20. Citation on PubMed or Free article on PubMed Central
  • Matern D, Seydewitz HH, Bali D, Lang C, Chen YT. Glycogen storage disease type I: diagnosis and phenotype/genotype correlation. Eur J Pediatr. 2002 Oct;161 Suppl 1:S10-9. doi: 10.1007/s00431-002-0998-5. Epub 2002 Jul 27. Citation on PubMed
  • van Schaftingen E, Gerin I. The glucose-6-phosphatase system. Biochem J. 2002 Mar 15;362(Pt 3):513-32. doi: 10.1042/0264-6021:3620513. Citation on PubMed or Free article on PubMed Central

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.