G6PD Deficiency

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G6PD Deficiency is a X-linked recessive disorder that causes episodic breakdown of red blood cells.

Specifically, the disease is caused by decreased activity of glucose-6-phosphate dehydrogenase or G6PD (see HMP/Pentose Phosphate Shunt - coming soon!), which converts glucose-6-phosphate to 6-phosphogluconate. More importantly, G6PD normally produces NADPH for the cell, and patients with G6PD have low NADPH levels intracellularly.

Decreased NADPH prevents the reduction of GSH (glutathione), which typically scavenges free radicals produced by oxidative stress. Red blood cells (RBCs) are particularly affected, and hemolysis occurs due to oxidative damage.

Patients experience episodic hemolysis when exposed to oxidizing agents (e.g. fava beans, rifampin), or in the setting of infection (e.g. upper respiratory infection). Blood smears of affected patients will reveal Heinz bodies, precipitated hemoglobin deposits in RBCs, as well as the presence of bite cells (degmacytes), caused by the removal of Heinz bodies by splenic macrophages.

Find this G6PD Deficiency mnemonic and more mnemonics for Metabolic Disorders among Pixorize's visual mnemonics for the USMLE Step 1 and NBME Shelf Exams.