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GCK gene


Normal Function

The GCK gene provides instructions for making a protein called glucokinase. This protein plays an important role in the breakdown of sugars (particularly glucose) in the body. Glucokinase is primarily found in the liver and in beta cells in the pancreas. Beta cells produce and release (secrete) the hormone insulin, which helps regulate blood glucose levels by controlling how much glucose is passed from the bloodstream into cells to be used as energy. Glucokinase acts as a sensor, recognizing when the level of glucose in the blood rises and helping stimulate the release of insulin from beta cells to control it. In the liver, glucokinase helps determine when excess glucose should be taken in and converted to glycogen, which is a major source of stored energy in the body.

Health Conditions Related to Genetic Changes

Maturity-onset diabetes of the young

Mutations in the GCK gene cause maturity-onset diabetes of the young (MODY), which is a group of conditions characterized by abnormally high blood glucose levels. This form of diabetes usually begins before age 30. GCK gene mutations cause a type known as GCK-MODY (also called MODY2). Affected individuals usually have mildly elevated blood glucose levels from birth, although they typically have no symptoms associated with the condition, and diabetes-related complications are extremely rare.

Most GCK gene mutations involved in GCK-MODY change single protein building blocks in the glucokinase protein or result in an abnormally short version of the protein. The altered protein may be broken down, or the function may be impaired, reducing glucokinase activity in cells. As a result, beta cells are less able to detect changes in blood glucose and release insulin to control it, so blood glucose remains elevated.

More About This Health Condition

Congenital hyperinsulinism

MedlinePlus Genetics provides information about Congenital hyperinsulinism

More About This Health Condition

Gestational diabetes

MedlinePlus Genetics provides information about Gestational diabetes

More About This Health Condition

Permanent neonatal diabetes mellitus

MedlinePlus Genetics provides information about Permanent neonatal diabetes mellitus

More About This Health Condition

Other Names for This Gene

  • ATP:D-glucose 6-phosphotransferase
  • Hexokinase type IV
  • HK4

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


  • Froguel P, Zouali H, Vionnet N, Velho G, Vaxillaire M, Sun F, Lesage S, Stoffel M, Takeda J, Passa P, et al. Familial hyperglycemia due to mutations in glucokinase. Definition of a subtype of diabetes mellitus. N Engl J Med. 1993 Mar 11;328(10):697-702. doi: 10.1056/NEJM199303113281005. Citation on PubMed
  • Negahdar M, Aukrust I, Molnes J, Solheim MH, Johansson BB, Sagen JV, Dahl-Jorgensen K, Kulkarni RN, Sovik O, Flatmark T, Njolstad PR, Bjorkhaug L. GCK-MODY diabetes as a protein misfolding disease: the mutation R275C promotes protein misfolding, self-association and cellular degradation. Mol Cell Endocrinol. 2014 Jan 25;382(1):55-65. doi: 10.1016/j.mce.2013.08.020. Epub 2013 Aug 31. Citation on PubMed
  • Osbak KK, Colclough K, Saint-Martin C, Beer NL, Bellanne-Chantelot C, Ellard S, Gloyn AL. Update on mutations in glucokinase (GCK), which cause maturity-onset diabetes of the young, permanent neonatal diabetes, and hyperinsulinemic hypoglycemia. Hum Mutat. 2009 Nov;30(11):1512-26. doi: 10.1002/humu.21110. Citation on PubMed
  • Steele AM, Shields BM, Wensley KJ, Colclough K, Ellard S, Hattersley AT. Prevalence of vascular complications among patients with glucokinase mutations and prolonged, mild hyperglycemia. JAMA. 2014 Jan 15;311(3):279-86. doi: 10.1001/jama.2013.283980. 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.