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Normal Function
The G6PD gene provides instructions for making an enzyme called glucose-6-phosphate dehydrogenase. This enzyme, which is active in virtually all types of cells, is involved in the normal processing of carbohydrates. It plays a critical role in red blood cells, which carry oxygen from the lungs to tissues throughout the body. This enzyme helps protect red blood cells from damage and premature destruction.
Glucose-6-phosphate dehydrogenase is responsible for the first step in the pentose phosphate pathway, a series of chemical reactions that convert glucose (a type of sugar found in most carbohydrates) to another sugar, ribose-5-phosphate. Ribose-5-phosphate is an important component of nucleotides, which are the building blocks of DNA and its chemical cousin RNA. This chemical reaction produces a molecule called NADPH, which plays a role in protecting cells from potentially harmful molecules called reactive oxygen species. These molecules are byproducts of normal cellular functions. Reactions involving NADPH produce compounds that prevent reactive oxygen species from building up to toxic levels within cells. The production of NADPH by glucose-6-phosphate dehydrogenase is essential in red blood cells, which are particularly susceptible to damage by reactive oxygen species because they lack other NADPH-producing enzymes.
Health Conditions Related to Genetic Changes
Glucose-6-phosphate dehydrogenase deficiency
More than 200 variants (also called mutations) that cause glucose-6-phosphate dehydrogenase deficiency have been identified in the G6PD gene. Almost all of these variants lead to changes in single building blocks (amino acids) in the glucose-6-phosphate dehydrogenase enzyme. These changes disrupt the normal structure and function of the enzyme or reduce the amount of the enzyme produced in cells.
Without enough functional glucose-6-phosphate dehydrogenase, red blood cells are unable to protect themselves from the damaging effects of reactive oxygen species. The damaged cells are likely to rupture and break down prematurely (undergo hemolysis). Factors such as infections, certain drugs, and ingesting fava beans can increase the levels of reactive oxygen species, causing red blood cells to undergo hemolysis faster than the body can replace them. This loss of red blood cells causes the signs and symptoms of hemolytic anemia, which is a characteristic feature of glucose-6-phosphate dehydrogenase deficiency.
More About This Health ConditionOther Names for This Gene
- G6PD1
- G6PD_HUMAN
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
References
- Biochemistry (fifth edition, 2002): Glucose 6-Phosphate Dehydrogenase Plays a Key Role in Protection Against Reactive Oxygen Species
- Cappellini MD, Fiorelli G. Glucose-6-phosphate dehydrogenase deficiency. Lancet. 2008 Jan 5;371(9606):64-74. doi: 10.1016/S0140-6736(08)60073-2. Citation on PubMed
- Efferth T, Schwarzl SM, Smith J, Osieka R. Role of glucose-6-phosphate dehydrogenase for oxidative stress and apoptosis. Cell Death Differ. 2006 Mar;13(3):527-8; author reply 529-30. doi: 10.1038/sj.cdd.4401807. No abstract available. Citation on PubMed
- Luzzatto L, Nannelli C, Notaro R. Glucose-6-Phosphate Dehydrogenase Deficiency. Hematol Oncol Clin North Am. 2016 Apr;30(2):373-93. doi: 10.1016/j.hoc.2015.11.006. Citation on PubMed
- Verrelli BC, McDonald JH, Argyropoulos G, Destro-Bisol G, Froment A, Drousiotou A, Lefranc G, Helal AN, Loiselet J, Tishkoff SA. Evidence for balancing selection from nucleotide sequence analyses of human G6PD. Am J Hum Genet. 2002 Nov;71(5):1112-28. doi: 10.1086/344345. Epub 2002 Oct 11. Citation on PubMed or Free article on PubMed Central
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