G6PD Deficiency — Managing the World's Most Common Enzyme Disorder

G6PD (Glucose-6-Phosphate Dehydrogenase) deficiency is the most common human enzyme disorder, affecting an estimated 400 million people worldwide. The G6PD enzyme is essential for protecting red blood cells from oxidative damage. When the enzyme is deficient or dysfunctional due to a mutation in the G6PD gene, red blood cells become vulnerable to oxidative stress. When exposed to certain drugs, infections, or foods, the affected red cells are rapidly destroyed (hemolyzed), leading to anemia, jaundice, and dark urine. Between episodes, most patients are entirely well with normal blood counts.

The most important high-risk medications include primaquine and tafenoquine (used for malaria), dapsone (used for leprosy and certain skin conditions), rasburicase (used in oncology to prevent tumor lysis syndrome), nitrofurantoin (an antibiotic), and many sulfonamide antibiotics. Methylene blue should also be avoided. The risk varies with the specific G6PD variant — Class II patients (such as those with the Mediterranean variant) are generally more sensitive than Class III patients. Always inform every healthcare provider — including dentists and surgeons — about your G6PD status before any new prescription. A hematologist can help you build a comprehensive and personalized drug safety reference.

Yes. Fava beans (broad beans) contain compounds called vicine and convicine that are potent oxidants. In patients with Class I and Class II G6PD deficiency — particularly those with the Mediterranean, Canton, and similar severe variants — ingestion of fava beans can trigger a rapid and severe hemolytic episode, a condition known as favism. Even inhaling fava bean pollen has been reported to trigger hemolysis in highly sensitive individuals. Class III patients (such as those with the G6PD A− variant) are generally less susceptible, but complete avoidance is usually advised. If in doubt, consult a hematologist for variant-specific guidance.

G6PD deficiency follows an X-linked recessive inheritance pattern. The G6PD gene is located on the X chromosome. Males have only one X chromosome, so a single copy of the defective gene causes the condition. Females have two X chromosomes — if only one carries the mutation, they are carriers (usually asymptomatic or mildly affected). If both X chromosomes are affected, females can have significant enzyme deficiency. An affected father cannot pass the condition to his sons (who inherit the Y chromosome), but all of his daughters become carriers. A carrier mother has a 50% chance of passing the affected X chromosome to each child.

The standard diagnostic test is a quantitative G6PD enzyme activity assay performed on a blood sample. This test should ideally be done during a stable period — not during or immediately after a hemolytic crisis — because the young red cells (reticulocytes) released during recovery have higher enzyme activity and can give a falsely normal result. A qualitative fluorescent spot test (Beutler test) is used for initial screening. Molecular testing (G6PD gene sequencing) can identify the specific mutation and is particularly useful for carrier females with borderline enzyme activity and for genetic counseling. Peripheral blood smear findings — including bite cells and Heinz bodies — can support the diagnosis during an acute episode.

G6PD deficiency is one of the important causes of neonatal jaundice (yellowing of the skin in newborns). In an affected newborn, ongoing low-grade hemolysis combined with the immaturity of the liver's bilirubin-processing capacity can cause bilirubin to rise rapidly. If not managed promptly, very high bilirubin levels can cross the blood-brain barrier and cause kernicterus — a preventable form of brain damage. Treatment typically involves phototherapy (special blue lights that break down bilirubin in the skin). In severe cases, an exchange transfusion may be needed. With early identification and appropriate treatment, most G6PD-deficient newborns with jaundice recover completely without any long-term effects.

For the vast majority of people with G6PD deficiency — particularly those with Class III variants such as G6PD A− — life expectancy is entirely normal. With proper trigger avoidance, most people will go their entire lives without a significant hemolytic episode. Even patients with Class II variants (severe episodic hemolysis) can lead full, normal lives with appropriate knowledge and precautions. Class I patients, who have chronic ongoing hemolysis, do require regular hematology follow-up and management of related complications such as anemia and gallstones, but even this group generally maintains a good quality of life with appropriate specialist care.

There is currently no approved definitive treatment or genetic correction for G6PD deficiency. Management focuses on trigger avoidance, prompt treatment of hemolytic crises, and supportive care. Gene therapy research is in early preclinical stages and aims to correct the G6PD gene defect in hematopoietic stem cells — an approach that, if successful, could offer long-term correction. Small molecule pharmacological activators that could stabilize or enhance mutant G6PD protein function are also under investigation. For now, education and trigger avoidance remain the most effective tools available to patients and families.

Absolutely — and this is particularly critical. Oncology patients with G6PD deficiency face specific risks because several drugs used in cancer care (especially rasburicase, used to prevent tumor lysis syndrome, and some investigational compounds) are potent oxidants that can trigger severe hemolysis. Additionally, patients undergoing surgery or receiving general anesthesia should ensure their anesthesiologist is aware, as some agents may carry risk. Every specialist — including oncologists, surgeons, anesthesiologists, and infectious disease physicians — must know about your G6PD status before any procedure or medication change. CancerFax can help you communicate your G6PD status clearly to your international care team and coordinate with hematology specialists when oncology and enzyme deficiency management intersect.

Yes. CancerFax works with patients and families affected by G6PD deficiency who are seeking specialist hematology review, pharmacogenomic testing for precise variant identification, or guidance on navigating complex clinical situations — such as managing G6PD deficiency alongside a concurrent illness or cancer diagnosis. We can facilitate coordination with hematology specialists, help review medical records and translate reports, and provide structured access to institutions with expertise in inherited red cell enzyme disorders in India and internationally. If you or a family member has G6PD deficiency and needs expert guidance, please send your medical reports through our portal or reach out to our team directly.