Glucose-6-phosphate dehydrogenase (G6PD) deficiency

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Glucose-6-phosphate dehydrogenase (G6PD) deficiency


Genetic disorders


Alagille syndrome (NORD)

Familial adenomatous polyposis

Familial hypercholesterolemia

Hereditary spherocytosis

Huntington disease

Li-Fraumeni syndrome

Marfan syndrome

Multiple endocrine neoplasia

Myotonic dystrophy


Polycystic kidney disease

Treacher Collins syndrome

Tuberous sclerosis

von Hippel-Lindau disease




Cystic fibrosis

Friedreich ataxia

Gaucher disease (NORD)

Glycogen storage disease type I

Glycogen storage disease type II (NORD)

Glycogen storage disease type III

Glycogen storage disease type IV

Glycogen storage disease type V


Krabbe disease


Mucopolysaccharide storage disease type 1 (Hurler syndrome) (NORD)

Niemann-Pick disease type C

Niemann-Pick disease types A and B (NORD)

Phenylketonuria (NORD)

Polycystic kidney disease

Primary ciliary dyskinesia

Sickle cell disease (NORD)

Tay-Sachs disease (NORD)

Wilson disease

Cri du chat syndrome

Williams syndrome

Angelman syndrome

Prader-Willi syndrome

Beckwith-Wiedemann syndrome

Mitochondrial myopathy

Klinefelter syndrome

Turner syndrome

Fragile X syndrome

Friedreich ataxia

Huntington disease

Myotonic dystrophy

Down syndrome (Trisomy 21)

Edwards syndrome (Trisomy 18)

Patau syndrome (Trisomy 13)

Alport syndrome

Fragile X syndrome

Fabry disease (NORD)

Glucose-6-phosphate dehydrogenase (G6PD) deficiency


Lesch-Nyhan syndrome

Mucopolysaccharide storage disease type 2 (Hunter syndrome) (NORD)

Muscular dystrophy

Ornithine transcarbamylase deficiency

Wiskott-Aldrich syndrome

X-linked agammaglobulinemia

Autosomal trisomies: Pathology review

Miscellaneous genetic disorders: Pathology review

Muscular dystrophies and mitochondrial myopathies: Pathology review


Glucose-6-phosphate dehydrogenase (G6PD) deficiency


0 / 12 complete

USMLE® Step 1 questions

0 / 4 complete

High Yield Notes

13 pages


Glucose-6-phosphate dehydrogenase (G6PD) deficiency

of complete


USMLE® Step 1 style questions USMLE

of complete

A 32-year-old woman, gravida 2 para 1, at 33 weeks gestation comes to the emergency department complaining of nausea, vomiting, headache, blurry vision, and severe abdominal pain for the last hour. The abdominal pain is described as a 10/10 stabbing pain that radiates to the back. Her temperature is 38.4°C (101.1°F), pulse is 92/min, respirations are 20/min, and blood pressure is 178/106 mmHg. Laboratory tests are obtained and results are shown below. Antiphospholipid antibody titers are negative.  
Laboratory value  Result 
 Platelet count  56,000/mm3  
 Hemoglobin  9.8 g/dL 
 Reticulocyte count   4.2% 
 Haptoglobin  10 mg/dL 
 Prothrombin time  11 seconds  
 Partial thromboplastin time  29 seconds 
 Bleeding time  8 minutes  
Blood, plasma, serum  
 Lactate dehydrogenase (LDH)  380 U/L 
 Total bilirubin  5.1 mg/dL 
 Direct bilirubin  0.3 mg/dL 
 Alanine aminotransferase (ALT)  980 U/L 
 Aspartate aminotransferase (AST)  530 U/L 
Which of the following is the most likely diagnosis in this patient?

External References

First Aid









G6PD deficiency p. 77

Antimalarial drugs

G6PD deficiency p. 417

Aspirin p. 499

hemolysis in G6PD deficiency p. 251

Back pain

G6PD deficiency and p. 417

Dapsone p. 191

hemolysis in G6PD deficiency p. 251

Degmacytes p. 422

G6PD deficiency p. 77

Fava beans and G6PD deficiency p. 417

G6PD deficiency p. 417

in anemia taxonomy p. 425

degmacytes in p. 422

Heinz bodies in p. 424

Glutathione p. 81

in G6PD deficiency p. 417


G6PD deficiency p. 417

Hemolysis in G6PD deficiency p. 251

Hemolytic anemia p. 429

G6PD deficiency p. 77

Ibuprofen p. 499

hemolysis in G6PD deficiency p. 251

Isoniazid p. 194

hemolysis in G6PD deficiency p. 251


hemolysis in G6PD deficiency p. 251

Primaquine p. 154

hemolysis in G6PD deficiency p. 251

Sulfa drugs p. 253

G6PD deficiency from p. 417

Sulfonamides p. 191

hemolysis in G6PD deficiency p. 251


Glucose-6-phosphate dehydrogenase deficiency, or G6PD deficiency, is a genetic disorder characterized by decreased levels of glucose-6-phosphate dehydrogenase, which leads to the destruction of red blood cells.

Normally, as a part of the metabolic process, our body produces free radicals like hydrogen peroxide, or H2O2.

Free radicals can damage the cells in many ways including destroying the DNA, proteins, and the cell membrane.

Now, we have a molecule in our body called glutathione which acts as an antioxidant and goes around and neutralizes these free radicals.

In order to function, these molecules need to be in the reduced state where they can donate an electron to the H2O2 and convert them into harmless water and oxygen.

However this causes the glutathione to become oxidized, so before it can get back to work, an enzyme called glutathione reductase will use an NADPH as an electron donor and and reduce the oxidized glutathione back into its working state.

After giving up its electron, the NADPH will become NADP+.

So to replenish the supply of NADPH, we have the glucose-6-phosphate dehydrogenase enzyme, or G6PD, which reduces NADP+ back to NADPH by oxidizing a glucose-6-phosphate.

Glucose-6-phosphate is a metabolite of glucose so we usually have a ready supply of this molecule as long as we are not starving.

Now G6PD deficiency is caused by mutations on the G6PD gene which is found on the X chromosome and thus it’s an X-linked recessive genetic condition and it almost exclusively manifests as a disease in men, since they have one X and one Y chromosome, so if the one and only chromosome has the mutation, then they have the disorder.

Women on the other hand have two X chromosomes, so those with an X chromosome that has the mutation, still have another X chromosome with a normal copy of the gene and thus females are usually carriers and only transmit the disease to their sons.

The G6PD mutations cause defective G6PD enzymes to be produced and these have a shorter half-life, meaning they don’t last as long as the normal enzymes.

There are two common types of G6PD deficiency: a Mediterranean and an African variant.

The Mediterranean variant is characterized by a more markedly reduced half-life of G6PD.

Now, sometimes this can actually be an advantage since it provides protection against falciparum malaria.

G6PD deficiency makes the parasite-infected erythrocyte more susceptible to dying from oxidants, which will also kill the malaria parasites.


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  2. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  3. "Yen & Jaffe's Reproductive Endocrinology" Saunders W.B. (2018)
  4. "Bates' Guide to Physical Examination and History Taking" LWW (2016)
  5. "Robbins Basic Pathology" Elsevier (2017)
  6. "Glucose-6-phosphate dehydrogenase deficiency" Best Practice & Research Clinical Haematology (2000)
  7. "Laboratory diagnosis of G6PD deficiency. A British Society for Haematology Guideline" British Journal of Haematology (2020)
  8. "Laboratory diagnosis of G6PD deficiency. A British Society for Haematology Guideline" British Journal of Haematology (2020)

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