G6PD Deficiency By Mike Lau 9.5

(Glucose 6 dehydrogenase deficiency)

G6PD deficiency is a hereditary (genetic) disease where the body is insufficient of the enzyme “glucose 6 phosphate dehydrogenase” (G6PD) in your body. G6PD aids the functioning of red blood cells, protecting them from harmful byproducts called "reactive oxygen species" (ROS) which occur when certain drugs or food (e.g. fava beans) are consumed. So, when certain food or drugs that release a lot of ROS into human body are consumed by a G6PD deficient patient, it could trigger hemolysis (the destruction of red blood cells) since there is not enough G6PD to protect the red blood cells from the ROS produced, causing oxidative stress or damage to red blood cells.
G6PD deficiency can be diagnosed by red blood cell counts to look at the activity of G6PD in the patient’s cells.
Numerous destroyed red blood cells due to the lack of protection from G6PD
The enzyme glucose 6 phosphate dehydrogenase.


Most people with G6PD deficiency do not show any symptoms. But sometimes, symptoms show up at later stages of an individual’s life rather than at early periods. Most cases of G6PD deficiency are not very severe and would rarely lead to death. However, the red blood cells of some G6PD deficient patients are destructed by the consumption of certain food and drugs, which leads to hemolytic anemia. Normally, the bone marrow will make more red blood cells due to the destruction, but if the rate of the destruction of red blood cells is higher than the creation of red blood cells, hemolytic anemia might occur and cause:
- Paleness in skin
- Fatigue
- Rapid heart rate
- Jaundice - yellowing of skin and eyes
- Dark colored urine
- Enlarged spleen

Victims suffering from severe symptoms will need to be hospitalized.
A boy with G6PD deficiency showing jaundice of the sclera (eye white.)


G6PD deficiency is a non-infectious disease, it is passed on genetically from one or both parents. The mutations that cause G6PD deficiency are found on the long arm of the X chromosome. G6PD deficiency is more commonly found and more severe in males because they have only one X chromosome. Females, who carry two X chromosomes, are mostly suffering from mild G6PD deficiency since it is required to have both X chromosomes to carry the mutant genes to be affected by the disease. So, G6PD deficiency will normally be less severe and less common in females, but G6PD deficient carriers could still pass on the mutant gene to their offsprings.
Patients with the mutant gene either produce red blood cells that do not create a sufficient amount of G6PD, or produce G6PD that function abnormally.
Affecting around 400 million people on earth, G6PD deficiency is the most common enzyme deficiency. African Americans and males inheriting the Mediterraneans are more commonly diagnosed with G6PD deficiency. Africa and the Mediterranean basin are high risk areas for the disease malaria. However, the parasites that causes malaria does not survive well in G6PD deficient red blood cells, so, it is believed that the deficiency emerged as a defense against malaria.
In the case of the genetic diagram above, there is only a quarter of a chance to have an affected child (son.) While there is no chance at all to have an affected daughter, and that it is only possible to either have a carrier daughter or an unaffected daughter


Like most genetic diseases, G6PD deficiency could not be treated. What should be done is to treat the symptoms of G6PD deficiency when they appear, and to avoid certain drugs or food that trigger hemolysis:
- Fava beans/broad beans
- Some antibiotics
- A few antimalarial (e.g. quinine)
- Moth balls
- Aspirin

Above are the infamous fava beans, and should be avoided by G6PD deficient patients due to the fact that fava beans release a lot of reactive oxygen species


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