G6PD Deficiency
(Glucose-6-Phosphate Dehydrogenase Deficiency)
G6PD Deficiency, a disorder involving the X-chromosome, was once thought to be symptomatic only in men. G6PD Deficiency is now known to be slightly more common in women than men though the symptoms are generally not as severe unless both X-chromosomes are affected. When it was discovered that G6PD Deficiency was a genetic disorder in 1953 by the late Dr. Beutler et al, they thought it was a recessive disorder. Since women have two copies of the X-chromosome, they believed women would not be affected unless BOTH chromosomes had the G6PD Deficiency mutation. Recent findings however have shown that it is NOT recessive and women with only one affected chromosome vary in severity from mild to severe. See Women and G6PD Deficiency.
The most notable symptom of G6PD Deficiency is hemolytic anemia caused by ingestion of drugs, food and other substances, known as triggers, which cause oxidative stress. G6PD Deficiency is in fact the most common genetic enzyme deficiency affecting an estimated 600 million people world wide.
For those unfamiliar with G6PD Deficiency, the best place to start is with the G6PD Deficiency Overview page. The most important thing to learn is that certain drugs, foods and other substances, or triggers, cause those with G6PD Deficiency or Favism to lose red blood cells. For a list of these contraindicated substances, go to our Contraindicated Substances page.
G6PD Deficiency Causes
Simply put, it is an inherited disorder and cannot be contracted in any other way. See the
Inheritance page for more information.
Diagnosing G6PD Deficiency
The diagnosis of G6PD deficiency is made by a quantitative spectrophotometric analysis or, more commonly, by a rapid fluorescent spot test detecting the generation of NADPH from NADP. The test is positive if the blood spot fails to fluoresce under ultraviolet light. In field research, where quick screening of a large number of patients is needed, other tests have been used, however, they require definitive testing to confirm an abnormal result. Tests based on polymerase chain reaction detect specific mutations and are used for population screening, family studies, or prenatal diagnosis.
Diagnostic problems
In patients with acute hemolysis, testing for G6PD deficiency may be reported falsely negative because older erythrocytes with a higher enzyme deficiency have been hemolyzed. Young erythrocytes and reticulocytes have normal or near-normal enzyme activity. Female heterozygotes may be hard to diagnose because of X-chromosome mosaicism leading to a partial deficiency that will not be detected reliably with some screening tests.
Worldwide G6PD Deficiency Prevelence
Aproximately 600 million people (10 percent of the population) world wide are G6PD Deficient. It is most common among people of Mediterranean, African, Asian and Middle Eastern decent though recent data produced by modern testing is not available. This website gets visits from almost every country on earth. The only countries not represented are very technologically challenged. New G6PD Deficiency tests are much more accurate and suggest the number of G6PD Deficient people is higher than now reported, especially in women. As an example, the Philippines, which showed few or no cases on G6PD Deficiency distribution maps, now that newborn screening has been implemented, is reporting that 12% of its population is affected.
G6PD Deficiency Variants
More than
440 different variants of G6PD Deficiency have been identified so far ranging from severe deficiency to mild. More than 80 of them are accompanied by Chronic Non-spherocytic Hemolytic Anemia. G6PDD is commonly put into one of three classes as follows:
- Class I - Less than 10% G6PD activity accompanied by Chronic Non-spherocitic Hemolytic Anemia (CNSHA). The most severe form of G6PDD.
- Class II - Less than 10% G6PD activity. Severe.
- Class III - 10% - 60% G6PD activity. Moderate to mild.
There are two other classes that range from very mild to too much G6PD, but are not considered here as they do not pose much of a problem.
Favism.
Favism has been known since antiquity. Everyone with Favism is G6PD Deficient but not all with G6PD Deficiency have Favism. The term comes from the Fava Bean and those with Favism hemolyze when they come into contact with the bean. See the
Favism Page for more information.
G6PD Deficiency Treatment or cure.
No. There is no known cure nor do you grow out of it. It is a life long condition. The only thing you can do is
avoid substances which cause oxidative stress and that use G6PD. Carbohydrates require G6PD for the body to change them into energy for example.
Legumes (especially the Fava Bean) contain the proteins vicine, convicine and isouramil which cause hemolysis.
Symptoms of G6PD Deficiency
Symptoms include
hemolytic anemia caused by ingestion or exposure to certain triggers. Anemia in turn causes jaundice, pale skin or finger nails, lethargy, exhaustion, shortness of breath and fever, among others. These symptoms usually go away on their own when exposure to the trigger is removed.
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