Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common enzyme defect with over 400 million cases globally. G6PD deficiency is a chronic, inherited condition with no known cure. Mutations in the G6PD gene can cause premature hemolysis due to an impairment in the enzyme G6PD, which normally functions to protect red blood cells from oxidative stress. Epidemiologists have hypothesized that G6PD deficiency is protective against malarial outbreaks, explaining its high prevalence and worldwide distribution. It follows an X-linked recessive inheritance pattern and is more common in males. G6PD deficiency is a global disease with highest prevalence in the tropics and subtropics of the Eastern Hemisphere: Mediterranean Europe, Africa, and South Asia. A few unique populations, such as Kurdish Jews, Nigerians, Thais, and Sardinians, have a very high prevalence of G6PD deficiency.

G6PD deficiency has variable phenotypes attributed to the severity of the enzyme deficiency. G6PD is classified into 5 variations correlating to the amount of enzyme activity. Affected neonates may present with hyperbilirubinemia and hemolytic anemia, but many patients are asymptomatic. Some patients will have a chronic anemia from ongoing hemolysis, while others will be asymptomatic until a trigger, often environmental (ie, food or medication) or infectious, incites a hemolytic episode.

Signs and symptoms include pallor, dark urine, dyspnea, tachycardia, jaundice, and fatigue. Severe anemic hemolysis may occur in patients who have been exposed to bacterial or viral infections, the antimalarial drug primaquine, some antibiotics, or fava beans.

Management focuses on minimizing exposure to potential triggers that can incite hemolytic events and supportive management during anemic episodes.