Glucose-6-phosphate dehydrogenase deficiency
| Glucose-6-phosphate dehydrogenase deficiency | |
|---|---|
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| Glucose-6-phosphate dehydrogenase | |
| Classification and external resources | |
| Specialty | Medical genetics |
| ICD-10 | D55.0 |
| ICD-9-CM | 282.2 |
| OMIM | 305900 |
| DiseasesDB | 5037 |
| MedlinePlus | 000528 |
| eMedicine | med/900 |
| Patient UK | Glucose-6-phosphate dehydrogenase deficiency |
| MeSH | D005955 |
Glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency), also known as favism (after the fava bean), is an X-linked recessive inborn error of metabolism that predisposes to hemolysis (spontaneous destruction of red blood cells) and resultant jaundice in response to a number of triggers, such as certain foods, illness, or medication. It is particularly common in people of Mediterranean and African origin. The condition is characterized by abnormally low levels of glucose-6-phosphate dehydrogenase, an enzyme involved in the pentose phosphate pathway that is especially important in the red blood cell. G6PD deficiency is the most common human enzyme defect. There is no specific treatment, other than avoiding known triggers. In the United States, no genetic screening of prospective parents is recommended, as the symptoms only show in part of the carriers and when that is the case, they can be prevented or controlled, and as a result the disease generally has no impact on the lifespan of those affected. However, globally G6PD deficiency has resulted in 4,100 deaths in 2013 and 3,400 deaths in 1990.
Carriers of the G6PD allele appear to be protected to some extent against malaria, and in some cases affected males have shown complete immunity to the disease. This accounts for the persistence of the allele in certain populations in that it confers a selective advantage.
Most individuals with G6PD deficiency are asymptomatic.
Symptomatic patients are almost exclusively male, due to the X-linked pattern of inheritance, but female carriers can be clinically affected due to unfavorable lyonization, where random inactivation of an X-chromosome in certain cells creates a population of G6PD-deficient red blood cells coexisting with normal red cells. A typical female with one affected X chromosome will show the deficiency in approximately half of her red blood cells. However, in rare cases, including double X deficiency, the ratio can be much more than half, making the individual almost as sensitive as a male.
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