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G6PD (Glucose-6-Phosphate Dehydrogenase) Deficiency

What is G6PD deficiency?

G6PD deficiency is the lack of glucose-6-phosphate dehydrogenase (an enzyme present in red blood cells) in the blood, which can cause a type of anemia known as hemolytic anemia. Red blood cells carry oxygen in the body and G6PD protects these cells from molecules called reactive oxygen that may build up when you have a fever or take certain medications. If there are too many of these chemicals, they can destroy the red blood cells, causing hemolytic anemia. G6PD deficiency is inherited--people are born with the deficiency. It occurs most often in males.

What is hemolytic anemia?

Hemolytic anemia is a disorder in which the red blood cells are destroyed faster than the bone marrow can produce them. In G6PD deficiency, hemolytic anemia is most often triggered by infection (bacterial or viral) or by taking certain medications.  

What are the symptoms of hemolytic anemia?

The following are the most common symptoms of hemolytic anemia. However, each individual may experience symptoms differently. Symptoms may include:

  • Abnormal paleness or lack of color of the skin

  • Jaundice, or yellowing of the skin, eyes, and mouth

  • Dark colored urine

  • Fever

  • Weakness

  • Dizziness

  • Confusion

  • Intolerance to physical activity

  • Enlargement of the spleen and liver

  • Increased heart rate (tachycardia)

  • Heart murmur

The symptoms of hemolytic anemia may resemble other blood disorders or medical problems. Always consult your doctor for a diagnosis.

Why be concerned about G6PD deficiency?

Certain medicines, foods, and other items can cause reactive oxygen to build up in the body. People with G6PD deficiency cannot protect their red blood cells against the buildup of this reactive oxygen and the blood cells are destroyed, causing anemia. Therefore, people with G6PD deficiency need to avoid exposing themselves to certain medicines, such as aspirin (acetylsalicylic acid), certain antibiotics used to treat infections, fava beans, and moth balls.

What causes G6PD deficiency?

G6PD deficiency is inherited by a gene on the X chromosome. Chromosomes are the structures in our cells which contain our genes; genes code for all of our traits, such as eye color and blood type. All humans have 46 chromosomes, or 23 pairs; the last pair determines gender: females have two X chromosomes, while males have one X and one Y chromosome. G6PD deficiency is inherited from females who carry one copy of the gene on one of their X chromosomes. Sons who receive the gene have G6PD deficiency, and daughters who receive the gene are carriers (who generally do not show any symptoms). The deficiency is rare in females because the mutation would have to occur in both copies of the gene to cause the disorder, whereas, in males, only one abnormal copy of the gene is required.

Certain ethnic groups have an increased incidence of G6PD deficiency than others. G6PD deficiency is seen in about 10 percent of African-American males in the U.S., and is also common in people from the Mediterranean area, Africa, or Asia. The severity of G6PD deficiency differs among different populations. In the most common form in the African-American population, the deficiency is mild and the hemolysis (destruction of red blood cells) affects primarily older red blood cells. In Caucasians, G6PD deficiency tends to be more serious, as even young red blood cells are affected.

How is G6PD deficiency diagnosed?

G6PD deficiency can be diagnosed by a simple blood test. If your ancestors come from an area where G6PD deficiency is common, or if you have family history of G6PD deficiency or unknown anemia, you should consult your doctor about having this blood test. However, the blood test may be normal in a patient with G6PD deficiency if it is done during or immediately following an acute episode of hemolysis. 

Treatment for G6PD deficiency

In most cases, G6PD deficiency does not cause problems for an individual, unless they are exposed to medications or foods which may damage their blood cells. Persons with G6PD deficiency can tolerate small amounts of these exposures, depending on the specific defect present in the gene. Specific treatment for G6PD deficiency anemia will be determined by your doctor based on:

  • Your age, overall health, and medical history

  • Extent of the disease

  • Your tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the disease

  • Your opinion or preference

Treatment may include:

  • Avoidance of certain medications, foods, and environmental exposures

  • Informing health care providers that you have G6PD deficiency

  • Consulting with your doctor before taking any medication