Glucose-6-Phosphate Dehydrogenase Deficiency

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What is glucose-6-phosphate dehydrogenase deficiency?

Glucose-6-phosphate dehydrogenase deficiency is a genetic disorder that occurs most often in males. This condition mainly affects red blood cells, which carry oxygen from the lungs to tissues throughout the body. In affected individuals, a defect in an enzyme called glucose-6-phosphate dehydrogenase causes red blood cells to break down prematurely. This destruction of red blood cells is called hemolysis.

The most common medical problem associated with glucose-6-phosphate dehydrogenase deficiency is hemolytic anemia, which occurs when red blood cells are destroyed faster than the body can replace them. This type of anemia leads to paleness, yellowing of the skin and whites of the eyes (jaundice), dark urine, fatigue, shortness of breath, and a rapid heart rate. In people with glucose-6-dehydrogenase deficiency, hemolytic anemia is most often triggered by bacterial or viral infections or by certain drugs (such as some antibiotics and medications used to treat malaria). Hemolytic anemia can also occur after eating fava beans or inhaling pollen from fava plants (a reaction called favism).

Glucose-6-dehydrogenase deficiency is also a significant cause of mild to severe jaundice in newborns. Many people with this disorder, however, never experience any signs or symptoms.

How common is glucose-6-phosphate dehydrogenase deficiency?

An estimated 400 million people worldwide have glucose-6-phosphate dehydrogenase deficiency. This condition occurs most frequently in certain parts of Africa, Asia, and the Mediterranean. It affects about 1 in 10 African-American males in the United States.

What genes are related to glucose-6-phosphate dehydrogenase deficiency?

Mutations in the G6PD gene cause glucose-6-phosphate dehydrogenase deficiency.

The G6PD gene provides instructions for making an enzyme called glucose-6-phosphate dehydrogenase. This enzyme is involved in the normal processing of carbohydrates. It also protects red blood cells from the effects of potentially harmful molecules called reactive oxygen species. Reactive oxygen species are byproducts of normal cellular functions. Chemical reactions involving glucose-6-phosphate dehydrogenase produce compounds that prevent reactive oxygen species from building up to toxic levels within red blood cells.

If mutations in the G6PD gene reduce the amount of glucose-6-phosphate dehydrogenase or alter its structure, this enzyme can no longer play its protective role. As a result, reactive oxygen species can accumulate and damage red blood cells. Factors such as infections, certain drugs, or ingesting fava beans can increase the levels of reactive oxygen species, causing red blood cells to be destroyed faster than the body can replace them. A reduction in the amount of red blood cells causes the signs and symptoms of hemolytic anemia.

Researchers believe that carriers of a G6PD mutation may be partially protected against malaria, an infectious disease carried by a certain type of mosquito. A reduction in the amount of functional glucose-6-dehydrogenase appears to make it more difficult for this parasite to invade red blood cells. Glucose-6-phosphate dehydrogenase deficiency occurs most frequently in areas of the world where malaria is common.

How do people inherit glucose-6-phosphate dehydrogenase deficiency?

This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation must be present in both copies of the gene to cause the disorder. Males are affected by X-linked recessive disorders much more frequently than females. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Source: National Institutes of Health

Research on life sciences published by scientists at University Hospital

"The disorders are most prevalent in the Mediterranean area, in Asia and Africa. The Scandinavian countries, among others, have seen a boom in immigration during the past 20 years, and therefore migration makes haemoglobinopathies as well as G6PD deficiency increasingly more important from a differential diagnostic perspective in most countries," wrote E. Theodorsson and colleagues, University Hospital.

The researchers concluded: "The purpose of the present special issue of the Journal is to summarize current epidemiological data and elucidate trends and practices in the laboratory diagnosis of these disorders."

Theodorsson and colleagues published their study in Scandinavian Journal of Clinical and Laboratory Investigation (Haemoglobinopathies and glucose-6-phosphate dehydrogenase deficiency in a Scandinavian perspective. Scandinavian Journal of Clinical and Laboratory Investigation, 2007;67(1):3-10).

For more information, contact E. Theodorsson, University Hospital, IBK, Clinical Chemistry, Linkoping, Sweden.

Publisher contact information for the Scandinavian Journal of Clinical and Laboratory Investigation is: Taylor & Francis as, Cort Adelersgt 17, PO Box 2562, Solli, 0202 Oslo, Norway.

Keywords: Sweden, Life Sciences.

This article was prepared by Science Letter editors from staff and other reports. Copyright 2007, Science Letter via NewsRx.com.